Lyme borreliosis–from tick bite to diagnosis and treatment

Lyme borreliosis–from tick bite to diagnosis and treatment Abstract Lyme borreliosis is caused by certain genospecies of the Borrelia burgdorferi sensu lato complex, which are transmitted by hard ticks of the genus Ixodes. The most common clinical manifestation is erythema migrans, an expanding skin redness that usually develops at the site of a tick bite and eventually resolves even without antibiotic treatment. The infecting pathogens can spread to other tissues and organs, resulting in manifestations that can involve the nervous system, joints, heart and skin. Fatal outcome is extremely rare and is due to severe heart involvement; fetal involvement is not reliably ascertained. Laboratory support—mainly by serology—is essential for diagnosis, except in the case of typical erythema migrans. Treatment is usually with antibiotics for 2 to 4 weeks; most patients recover uneventfully. There is no convincing evidence for antibiotic treatment longer than 4 weeks and there is no reliable evidence for survival of borreliae in adequately treated patients. European Lyme borreliosis is a frequent disease with increasing incidence. However, numerous scientifically questionable ideas on its clinical presentation, diagnosis and treatment may confuse physicians and lay people. Since diagnosis of Lyme borreliosis should be based on appropriate clinical signs, solid knowledge of clinical manifestations is essential. Lyme borreliosis, clinical manifestations, diagnosis, treatment, Borrelia burgdorferi sensu lato, erythema migrans INTRODUCTION Lyme borreliosis is considered the most frequent tick-borne disease in the moderate climates of the northern hemisphere. The infection is caused by specific genospecies of Borrelia burgdorferi sensu lato (s.l.). Lyme borreliosis is a disease with diverse clinical presentations. Signs and symptoms allow proper diagnosis of the disease. It is obvious that there can be no diagnosis of Lyme borreliosis in the absence of clinical manifestations. Thus, the most important step in diagnosing Lyme borreliosis is that physicians acquire a good knowledge of the clinical features through clinical instruction and personal experience. Nevertheless, it is most supportive and enlightening to consult the available case definitions, guidelines, reviews and seminar articles in peer-reviewed publications in order to learn about evidence-based knowledge of Lyme borreliosis (Wormser et al.2006; Strle and Stanek 2009; Mygland et al.2010; Stanek et al.2011, 2012; Shancez et al.2016; Steere et al.2016). Caution should be exercised when consulting the web for comprehensive information on the disease complex as there are hundreds of sites available (Sood 2002) with a lot of misinformation. The most frequently affected organ in Lyme borreliosis is the skin, followed by the nervous system and joints. Certain spirochaetes of the B. burgdorferi s.l. complex are the causative agents of the disease. These Borrelia species occur in natural foci in vertebrate reservoir hosts, and in certain Ixodes tick species that are responsible for transmission to other vertebrates, including man. As a tick-borne disease, Lyme borreliosis shows relatively constant seasonal peaks of the skin manifestation erythema migrans (EM) following the seasonal activity of ticks, whereas disseminated or late disease may appear throughout the year. Uncritical interpretation of symptoms may sometimes lead to incorrect interpretation of laboratory test results. Not infrequently a positive serological result in an otherwise healthy person may lead to the misinterpretation of active Lyme borreliosis and be followed by unnecessary antibiotic treatment. On the contrary, some patients with typical signs remain undiagnosed and untreated. Physicians should also be aware that Lyme borreliosis in North America and in Europe differ in their clinical presentations in some respects (Strle et al.1999, 2011; Cerar et al.2016). A reliable clinical diagnosis of Lyme borreliosis is only possible in a case of typical EM. Other manifestations of Lyme borreliosis such as borrelial lymphocytoma on the ear lobe, meningoradiculoneuritis (Garin-Bujadoux-Bannwarth syndrome) and acrodermatitis chronica atrophicans (ACA) are also highly supportive of the diagnosis. However, with the exception of typical EM, laboratory confirmation is needed in any case that is clinically suspicious for Lyme borreliosis. It should also be emphasised that the traditional early dividing of Lyme borreliosis into numbered stages—following the syphilis model—is only partly in agreement with clinical findings. A more flexible descriptive terminology is recommended, namely early localised, early disseminated or late disease. The aim of this review article is to provide detailed information on the various clinical presentations of Lyme borreliosis with respect to diagnosis and treatment. The emphasis in this review is on European Lyme borreliosis; information on the disease in North America has been included for illustrative purposes. Lyme borreliosis or Lyme disease? Lyme borreliosis refers to a disease caused by particular infectious organisms of the B. burgdorferi s.l. complex. The earlier name of Lyme disease described a disease without a known cause and as sometimes used currently does not necessarily mean that an infectious organism is present. Namely, the term Lyme disease is now frequently but misleadingly applied to a broad spectrum of symptoms in cases of long-term illness where the infectious agent is unknown and not demonstrable, often referred to as ‘chronic Lyme disease’. It would therefore be desirable to emphasise Lyme borreliosis as the specific term. A look back into the history of Lyme disease shows that Lyme arthritis and Lyme carditis were first observed in the communities of Lyme, Old Lyme and East Haddam in Connecticut, USA (Steere et al.1977b) and Lyme disease was adopted for an enlarging spectrum of symptoms that were obviously linked to each other by an aetiology that remained unknown until the early 1980s (Steere et al.1977a). After the discovery of Borrelia in Ixodes scapularis ticks from Long Island, NY (Burgdorfer et al.1982; Barbour et al.1983), and their aetiologic role in these disorders (Benach et al.1983; Steere et al.1983b; Barbour 1984), the more specific term Lyme borreliosis was introduced (Stanek et al.1987a). This term also comprises the clinical manifestations erythema chronicum migrans, lymphadenosis benigna cutis/borrelial lymphocytoma, ACA and meningopolyneuritis that were known in Europe (Herxheimer and Hartmann 1902; Afzelius 1910; Lipschütz 1913; Bäverstedt 1943; Hörstrup and Ackermann 1973) decades before recognition of Lyme arthritis and are now linked together in a nosological entity. Although ‘Lyme’, the name of the small communities, appears to be irrelevant in describing the disease, the terms Lyme borreliosis and Lyme disease have been used extensively and will thus now remain to describe a disorder that exists in moderate climates throughout the northern hemisphere (Stanek et al.2012). Borrelia burgdorferi sensu lato—the pathogens Detailed information on the biology of B. burgdorferi s.l. and its infectious cycle is given in a review by Mannelli et al. (2012). Briefly, Borrelia are spirochaetal bacteria consisting of a protoplasmic cylinder surrounded by 7 to 12 endoflagellae inserted in both ends of the elongated (10–30 μm length) but slender (0.2–0.5 μm diameter) organisms and overlapping in the middle. The entire structure is enclosed by a flexible outer membrane (Barbour 1988) that does not contain lipopolysaccharide but is instead equipped with outer surface lipoproteins (Osps). Moreover, these borreliae harbour a linear chromosome—an almost unique feature in the bacterial domain (Barbour and Hayes 1986)—and several linear and circular plasmids in which relevant Osps are encoded. Among the currently described genospecies of B. burgdorferi s.l. (Stanek and Reiter 2011; Mannelli et al.2012), the prevailing pathogens of Lyme borreliosis in Europe are the genospecies B. afzelii, B. garinii, B. bavariensis (formerly B. garinii OspA type 4) and B. burgdorferi (B. burgdorferi sensu stricto). B. spielmanii, B. bissetii, B. valaisiana and B. lusitaniae have been identified as pathogens in single cases only (Picken et al.1996; Maraspin, Ruzic-Sabljic and Strle 2006; Fingerle et al.2008; Stanek and Reiter 2011; Stanek et al.2012; Stupica et al.2015). The predominant agent of Lyme borreliosis in North America is B. burgdorferi. In single cases, B. bissetti, B. americana and B. andersonii were found in human blood (Girard, Fedorova and Lane 2011; Clark, Leydet and Hartman 2013). Recently, B. mayonii was described as a novel genospecies and human pathogen in the B. burgdorferi sensu lato complex (Pritt et al.2016). Figure 1 illustrates the relative frequency of different B. burgdorferi s.l. genospecies isolated from the skin lesions of patients in Slovenia with EM (Strle et al.1996c; Ružić-Sabljić et al.2000; Stupica et al.2015), and Fig. 2 shows the relative frequency of different genospecies isolated from cerebrospinal fluid (CSF) (Ružić-Sabljić et al.2001; Strle et al.2006; Ogrinc et al.2013, 2016). Information on relative frequency of genospecies found in individual clinical manifestations of Lyme borreliosis is based on findings from only a few European countries, they may not be representative for a larger (European) geographic area. Figure 1. View largeDownload slide Distribution of genospecies (%) among 488 skin isolates of B. burgdorferi s.l. from Slovenian patients with erythema migrans (Ružić-Sabljić et al.2002). Figure 1. View largeDownload slide Distribution of genospecies (%) among 488 skin isolates of B. burgdorferi s.l. from Slovenian patients with erythema migrans (Ružić-Sabljić et al.2002). Figure 2. View largeDownload slide Distribution of genospecies (%) of B. burgdorferi s.l. among 120 CSF isolates from European patients with Lyme neuroborreliosis (Strle et al.2006). Figure 2. View largeDownload slide Distribution of genospecies (%) of B. burgdorferi s.l. among 120 CSF isolates from European patients with Lyme neuroborreliosis (Strle et al.2006). Tick bite and transmission of pathogens The vectors of B. burgdorferi s.l. are hard ticks of the genus Ixodes. The active developmental stages of larva, nymph and adult female each take a single blood meal. The adult male tick may take sporadic small meals. Borrelia burgdorferi s.l. is taken up with the blood when the tick, usually a larva or a nymph, feeds on an infected reservoir host. The spirochaete locates in the midgut of the tick and is transmitted by the next tick stage when it feeds on another vertebrate host, which can include man. The adult female is usually a dead end for B. burgdorferi s.l. because transovarial transmission is rare (Mannelli et al.2012; Rollend, Fish and Childs 2013; EUCALB 2010). The blood meal is a stimulus for B. burgdorferi s.l. to detach from the epithelium of the midgut of the tick, enter the haemolymph and migrate to the salivary glands. Blood meal results in an upregulation of surface proteins such as OspC, DbpA, DbpB and P66, and downregulation of OspA and OspB. The borreliae are then transmitted to the host with the saliva. Factors contained in tick saliva enhance the survival of the bacteria by attenuating the local immune response at the site of the tick bite, and co-feeding apparently increases the frequency of OspC variants (Rosa 2005; Pérez et al.2011). Strategies to overcome complement attacks play an important part in the immune evasion of borreliae (Kraiczy et al.2000; Kraiczy 2016). Borrelia bind to a variety of host tissue components such as plasmin and factor H, which may facilitate the tissue invasion process (Kraiczy and Stevenson 2013). One of the frequently asked questions is: What is the minimum feeding period required for an infected tick to transmit borreliae that eventually cause disease in humans? An answer was obtained from records of patients with EM in Austria and Slovenia. The records were evaluated independently and gave almost identical results (Strle et al.1996a; Stanek and Kahl 1999). Most of the patients had discovered the attached tick on the day after the putative tick attachment. In both countries, the feeding period of the ticks before detection and removal was more than 12 h in the majority of patients and in about a third it was more than 24 h. However, 14%–18% of exposed persons removed the tick within 6 h and subsequently developed EM (Fig. 3). The relatively early transmission in Europe compared with the USA is supported by findings in laboratory experiments on transmission (Kahl et. al. 1998). Figure 3. View largeDownload slide Reports from patients on the estimated duration (hours) of tick attachment before removal from the skin and subsequent erythema migrans. Results (%) from studies in Austria (AT, n = 254) and Slovenia (SI, n = 212). Figure 3. View largeDownload slide Reports from patients on the estimated duration (hours) of tick attachment before removal from the skin and subsequent erythema migrans. Results (%) from studies in Austria (AT, n = 254) and Slovenia (SI, n = 212). Asymptomatic infections In the USA, B. burgdorferi may cause asymptomatic infection in about 10% of patients (Steere et al.2003), while in a study of seroprevalence in Sweden, more than half of seropositive subjects did not remember having symptoms of Lyme borreliosis (Wilhelmsson et al.2016). These data suggest that in North America borrelial infections appear to lead to disease more frequently. Lyme borreliosis—the disease Lyme borreliosis can involve several organ systems and may have different clinical presentations. Information on the relative frequency of individual clinical manifestations of the disease in Europe is very limited. Skin is the most frequently involved tissue in Lyme borreliosis, and usually clinically the most characteristic, and thus provides clues for the diagnosis (Strle and Stanek 2009). The findings from Slovenia, which are not necessarily representative for whole Europe, are shown in Fig. 4. Figure 4. View largeDownload slide Frequency (%) of main clinical manifestations of Lyme borreliosis in adults (n = 745) and children (n = 275). Data of the year 2000 from the Department of Infectious Diseases at the University Medical Centre, Ljubljana, Slovenia. Figure 4. View largeDownload slide Frequency (%) of main clinical manifestations of Lyme borreliosis in adults (n = 745) and children (n = 275). Data of the year 2000 from the Department of Infectious Diseases at the University Medical Centre, Ljubljana, Slovenia. In the USA, EM is the presenting manifestation in approximately 80% of patients with Lyme borreliosis; in about 15% of patients, non-specific symptoms occur during summer without the skin lesion, and in the remaining 5%, the disease presents with a later manifestation of the illness, such as Lyme neuroborreliosis (LNB) or arthritis (Steere and Sikand 2003). Hereafter we present the main clinical characteristics of Lyme borreliosis, including some illustrative cases of different manifestations of the disease. All the patients presented as cases originated from, or were exposed to ticks in, Lyme borreliosis endemic regions. Skin manifestations EM, borrelial lymphocytoma (formerly lymphadenosis benigna cutis) and ACA are characteristic manifestations of Lyme borreliosis. Other skin manifestations such as scleroderma circumscripta, lichen sclerosus et atrophicus and cutaneous B-cell lymphoma may also be associated with Lyme borreliosis. Erythema migrans EM is defined as an erythematous skin lesion that develops days to weeks later at the site where borreliae were transferred into the skin by the bite of an infected tick (Fig. 5). The lesion typically begins as a red macula or papule and expands over days to weeks with or without central clearing. For a reliable diagnosis, a single primary lesion must reach ≥5 cm in diameter. A lesion <5 cm qualifies for the diagnosis of EM only if it develops at the site of a tick bite, if its onset has a free time interval of at least 2 days and if the lesion is enlarging (Stanek et al.2012). Multiple EM is defined as the presence of two or more skin lesions, one of which must fulfil the size criteria for solitary EM. Figure 5. View largeDownload slide Erythema migrans (EM) lesions: (a) EM shoulder, (b) EM knee pit, (c) EM lower leg, a day after onset of treatment, (d–f) EM ∼9 weeks after onset; tick bite in the axilla, (g) EM started at the breast 6 months before (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 5. View largeDownload slide Erythema migrans (EM) lesions: (a) EM shoulder, (b) EM knee pit, (c) EM lower leg, a day after onset of treatment, (d–f) EM ∼9 weeks after onset; tick bite in the axilla, (g) EM started at the breast 6 months before (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). EM, the most frequent manifestation of Lyme borreliosis, may represent about 90% of registered cases in countries of central Europe (Anonymus 2015). According to Borrelia skin culture results, EM in western, central and eastern Europe is caused predominantly by B. afzelii (70%–90%), less frequently by B. garinii (10%–20%), rarely by B. burgdorferi and only exceptionally by other species such as B. bissettii, B. spielmanii and as yet unidentifiable species. However, B. garinii dominates in north-eastern Europe (Oksi et al.2001; Stanek et al.2012). Between 58% and 73% of European patients with EM recall a previous tick bite at the site of the EM (Strle et al.2002) but only one in four patients with EM in the USA (Strle et al.1999; Wormser et al.2006). Histological examination of the dermis reveals mild superficial perivascular infiltration by lymphocytes and some histiocytes, sometimes accompanied by plasma cells and rarely by neutrophils (Stanek and Flamm 1991; de Koning and Duray 1993). The epidermis is usually not affected. The infiltration predominantly consists of macrophages and CD8+ and CD4+ T cells along with smaller numbers of B cells and plasma cells. Involvement of cell-mediated immune mechanisms in the initial host response to Lyme borreliae is indicated by the presence of T cells and increased numbers of Langerhans cells. High levels of the T-cell-active chemokines CXCL9 and CXCL10 and low levels of the B-cell-active chemokine CXCL13 have been demonstrated. CD3(+) T cells and CXCL9 have been shown by immunohistological methods (Müllegger et al.2007). The seasonal occurrence of EM is pronounced because the onset of the lesion usually occurs soon after the tick bite. Untreated EM may persist and expand over weeks to several months, their diameter ranging from a few centimetres to more than a metre (Fig. 5). In adult patients, EM is most often located on the lower extremities; in children, the upper part of the body is relatively more often involved (Berglund et al.1995; Strle 1999a; Logar et al.2004; Strle et al.2011). The location of EM is in accordance with data about location of tick bites (Robertson, Gray and Stewart 2000). Mild local symptoms such as mild itching, burning or pain at the site of EM may be recalled in about half of European patients with EM. A smaller proportion of patients (about one third) may experience systemic symptoms, such as fatigue and malaise, headache, myalgia and arthralgia, which are usually intermittent and often vary in intensity and location. Fever is an exception in adult European patients, whereas it is present more frequently in patients in the USA (Strle et al.1996c, 1999; Dandache and Nadelman 2008; Cerar et al. 2010; Ogrinc et al.2013). Further, EM in the USA has a greater frequency of abnormal findings including lymphadenopathy (39% vs 9%) and fever (15% vs 1%), and differences in the humoral immune response (Strle et al.1999). In multiple EM, the secondary lesions are similar in morphology to the initial solitary lesion but lack the indurated centre usually seen in primary lesions at the site of the tick bite; secondary lesions are also smaller and are only exceptionally associated with local itching or pain. They appear to be more frequent in children than in adults, and are apparently a more common finding in EM in the USA (Strle et al.1996a, b; Strle and Stanek 2009). Differential diagnoses comprise tick-bite or insect-bite hypersensitivity reaction, fungal infection such as tinea corporis (ring worm), erysipelas, urticaria, contact eczema, folliculitis, cellulitis, granuloma annulare and fixed drug eruption (Strle and Stanek 2009; Stanek et al.2012). Case 1. A 45-year-old woman experienced a tick bite on her right thigh in late June. Two weeks later, a small redness appeared at the site of the bite. The redness was mildly itchy and slowly expanding. Seven days later it began to fade in the middle, became ring-like and continued to spread, so that in the middle of September the erythema expanded over the whole right leg. With the exception of mild itching the patient had no other symptoms. This was the reason that she did not seek for medical help for more than 2 months after the onset of the lesion. Her doctor did not order any laboratory tests but prescribed the patient doxycycline 100 mg bid for 14 days. The skin lesion began to fade at the end of the first week of treatment and disappeared completely at the end of therapy. No other manifestations of Lyme borreliosis appeared within 1 year after the end of antibiotic treatment. Comment: A typical course of EM, including proper management and favourable outcome of the early Lyme borreliosis manifestation. Case 2. A 31-year-old woman presented mid May with a small erythematous area in her umbilicus. She claimed that she rubbed the umbilicus because of itching and found something black on her finger which could have been a tick. The possible tick bite was on 15 May. Since the redness was not indicative of EM at that time point, she was asked by her doctor to observe the skin area and to come in again if the erythematous area enlarges. She accepted but wished to learn about her antibody status against Lyme borreliae and therefore a blood sample was drawn. However, the patient did not come in when she recognised enlargement of the erythema but several weeks later, on 21 June. At this time, a typical EM was present around her umbilicus with a diameter of 22 × 15 cm. Treatment with phenoxymethyl penicillin was prescribed 1000 000 IU tid for 14 days and a second blood sample was drawn. The erythema disappeared after the first week of treatment. Serology showed a seroconversion from negative results with the first blood sample to highly positive IgG and IgM results, in both ELISA and immunblot, with the second. Comment: The ‘wait and watch’ policy is recommended when an attached tick is removed or when a lesion is small and not identifiable as EM. If serology is perfomed, then two blood samples are needed: one is taken at the first visit and the other 3 to 6 weeks later. Seroconversion or a significant increase in the concentration of pre-existing antibodies may be observed. However, the diagnosis of a typical EM must be made on clinical basis! Borrelial lymphocytoma Case 3. A 9-year-old girl spent most of the summer time in forested landscape. From May to August, she had at least 10 tick bites. In early September, her parents noticed a small induration and oedema of her left earlobe. The swelling slowly grew in size. The skin was initially red, and later it gradually turned violet. The girl had no other complaints. Examination at the end of November revealed a bluish-red left earlobe, almost entirely swollen and somewhat more firm. Otherwise physical examination was normal. Basic laboratory blood tests revealed no abnormalities. IgM and IgG serum antibodies to B. burgdorferi s.l. were detected. The ear lobe lesion disappeared about 2 weeks after 14 days treatment with amoxicillin; later on the girl had no complaints. Comment: A typical course and outcome of borrelial lymphocytoma in a child. Case 4. A 56-year-old woman recognised an attached tick on the left side of her chest after having collected mushrooms in the forest. Ten days later she noticed a red patch on the skin at the site of the tick bite. The patch slowly expanded. After 1 week, it began to fade in the centre and became ring-like. The lesion expanded to diameter of about 30 × 20 cm, and lasted for about 7 weeks. Approximately 10 days before it disappeared, the patient noticed that the mammilla of her left breast was swollen; it was sensitive to touch, and occasionally mildly itchy. The patient recalled tiredness and pain in the muscles of the limbs, headaches, dizziness and feeling of occasional irregular heartbeat. She visited her doctor for the first time about 3 weeks after the ring-like erythema lesion has disappeared. In the following 2 months, she was examined by an internist, cardiologist, neurologist and psychiatrist but the cause of her problems was not found. Her difficulties were interpreted as neurovegetative dystonia in association with menopause. An oncologist that she visited more than 4 months after the onset of the disease did not confirm suspicion of malignant breast disease but directed the patient to the Lyme borreliosis outpatient clinic. The nipple of the left breast was swollen, mildly hardened and minimally painful to touch; in the region of areola mammae, a tumour with a diameter of 3 cm was found. Otherwise the physical status of the patient was normal. High levels of IgG serum antibodies to B. burgdorferi s.l. were detected. Basic laboratory blood test results were in the normal range. The patient was treated with doxycycline 100 mg bid for 14 days. Fatigue, pains and dizziness disappeared by the end of treatment, while the breast tumour vanished completely in the following 6 weeks. One year later, the patient was without complaints but remained seropositive. Comment: A characteristic course and outcome of borrelial lymphocytoma in an adult person; diagnostic difficulties are usually due to limited knowledge. Borrelial lymphocytoma presents as a solitary swelling up to a few centimetres in diameter, and consists of a dense lymphocytic infiltration of dermis and subcutaneous tissue as a result of borrelial infection (Asbrink and Hovmark 1988; Strle et al.1992; Maraspin et al.2016). The infiltration is polyclonal with a predominance of B-lymphocytes and may show germinal centres (Asbrink and Hovmark 1988; Stanek and Flamm 1991). The predominance of B cells is in contrast with the findings in EM and ACA skin lesions where T cells prevail. High levels of the B-cell-active chemokine CXCL13 are found in this skin manifestation in contrast to EM and ACA (Müllegger et al.2007). Borrelial lymphocytoma is a rare manifestation of European Lyme borreliosis. It is more frequently observed in children than in adults: data from epidemiological studies and case records show a frequency of 1.5%–7% in children and 0.5%–2% in adults (Berglund et al.1995; Strle and Stanek 2009). In children, borrelial lymphocytoma is most frequently located on the ear lobe and in adults in the region of the areola mammae, rarely on the nose, arm, shoulder or scrotum (Strle et al.1996b). Borrelial lymphocytoma may appear after EM but sometimes together (Fig. 6) or even before EM. It also resolves eventually without treatment; however, sometimes it may take more than a year (Asbrink and Hovmark 1988; Strle et al.1992, 1996b). Other signs of Lyme borreliosis may develop in the course of untreated long-lasting borrelial lymphocytoma (Asbrink and Hovmark 1988; Strle et al.1992, 1996b). Accompanying systemic symptoms such as reported in case 3 are rare, but localised discomfort in the region of the areola mammae in cases of borrelial lymphocytoma of the breast appears to be a frequent finding. Antibodies to B. burgdorferi s.l. may be demonstrable in 50%–70% of patients at first visit. Basic blood tests usually show no abnormality (Strle et al.1992; Maraspin et al.2016). Figure 6. View largeDownload slide Borrelial lymphocytoma (BL): (a and b) BL on ear lobe, (c) BL on nipple surrounded by EM, (d) BL of nipple (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 6. View largeDownload slide Borrelial lymphocytoma (BL): (a and b) BL on ear lobe, (c) BL on nipple surrounded by EM, (d) BL of nipple (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Borrelial isolates from borrelial lymphocytoma are rare (Strle et al.1996b; Maraspin et al.2002, 2016). The isolation rate is about 1/3 (Maraspin et al.2016). The isolates most frequently belong to the genospecies B. afzelii, in some cases to B. garinii and B. burgdorferi; B. bissettii has been detected in one patient (Picken et al.1997; Maraspin et al.2002, 2016; Ružić-Sabljić et al.2002). Differential diagnosis requires histological examination, particularly in patients with breast lymphocytoma or lymphocytoma at other (atypical) locations if an association with borrelial infection cannot be established (Strle et al.1996b) and B-cell lymphoma and pseudolymphoma are considered (Asbrink and Hovmark 1988; Strle et al.1992, 1996b; Maraspin et al.2002; Lipsker 2007). Acrodermatitis chronica atrophicans Case 5. A 55-year-old female reported that she has been bitten almost every year by a number of ticks since her childhood, but she did not remember an erythema at the site of the bites. Six and a half years previous to her visit, the back of her left hand became swollen and the skin bluish red. Although there were some mild transient improvements, the skin lesion slowly enlarged. In the following 2 years, similar skin lesions also appeared on the right hand and on right foot and the distal part of her right leg. The swellings slowly vanished and were replaced by a more and more thinning skin, which was vulnerable and of bluish colour. In the area of the gradually enlarging skin lesions, tingling sensations and severe burning pain began to appear, becoming more and more annoying. Several months later—more than 2 years after she noticed skin changes—pain with slowly increasing severity appeared in small joints of hands and feet. In the following years, the joints become deformed. Due to the deformity of the fingers on her right foot, she had increasing problems with the footwear. During this time, she had two episodes of a swollen right knee which lasted for more than 1 month. Physical examination revealed skin involvement of the distal parts of the limbs: distal to the midpoint of the left upper arm, distal to the right elbow and distal to the middle of the right lower leg. In the proximal parts of the involved skin, the changes were disseminated in the form of patches, while more distally skin was involved homogeneously. The skin was bluish, atrophic, in some parts—in particular on the back of her hands—it was wrinkled, translucent and with numerous prominent veins. A neurologist diagnosed the presence of polyneuropathy, X-ray examination disclosed subluxation of fingers of the right foot. Histologic examination of the skin revealed teleangiectasias, interstitial infiltration of the dermis and subcutaneous tissue with lymphocytes and plasma cells and thin hyperkeratotic epidermis. Serological testing revealed high levels of specific IgG serum antibodies. Comment: A course of ACA with the involvement of skin, peripheral nerves and joints. ACA is a chronic skin manifestation of Lyme borreliosis seen almost exclusively in Europe (Steere 1989; Stanek and Strle 2003; Wormser et al.2006). In contrast to EM and borrelial lymphocytoma, ACA does not disappear spontaneously (Asbrink and Hovmark 1988). The lesion is most often located on acral parts of the body, usually on the extensor part of hands or feet, and initially is usually unilateral, later on it may become more or less symmetrical. A previous other manifestation of Lyme borreliosis is usually not recalled by these patients. ACA is more often diagnosed in women than in men and occurs only very exceptionally in children. Patients are usually over 40 years old (Asbrink and Hovmark 1988; Strle et al.2013b, Ogrinc et al.2017). The disorder accounts for about 3% of cases of Lyme borreliosis (Berglund et al.1995) and is most frequently caused by B. afzelii but also by B. garinii and B. burgdorferi (Picken et al.1998; Ružić-Sabljić et al.2000, 2002). Because of the long incubation time and the long duration of the skin lesions prior to diagnosis, a history of tick bites is not supportive. Histological findings in the early lesions are non-specific perivascular lymphocytic infiltrates; the epidermis is frequently thinned. Band-like and perivascular infiltrates consisting of lymphocytes and plasma cells are seen in the upper and middle portions of the dermis, often combined with oedema (de Koning and Duray 1993). Dilated blood vessels can be found in the superficial dermis. Peri-articular fibroid nodules may be present in the deeper portions of the dermis extending into the subcutaneous fat. The nodules consist of a homogeneous eosinophilic centre surrounded by irregular fascicles of collagen, onion-like. Perivascular infiltrates of lymphocytes and plasma cells are present predominantly in the peripheral parts of the lesion, and fibrosis is pronounced. In the late stage of ACA, cutaneous atrophy is present with more or less pronounced inflammation (Fig. 7). In very long-standing atrophic lesions, the inflammatory infiltrates are sparse or may even be absent; collagen and elastic fibres are strongly reduced and degenerated. In general, histologically constant findings in active ACA lesions are telangiectases and a lymphocytic infiltrate with a moderate-to-rich admixture of plasma cells (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986). However, the histopathological pattern is not diagnostic in itself (Brehmer-Andersson, Hovmark and Asbrink 1998). Figure 7. View largeDownload slide Acrodermatitis chronica atrophicans; atrophic skin (Picture by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 7. View largeDownload slide Acrodermatitis chronica atrophicans; atrophic skin (Picture by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Clinically, the involved region is usually oedematous; initially erythema and swelling may vary in intensity. In some patients, the cutaneous manifestations are confined to a heel that is swollen, sometimes discoloured and painful (Asbrink et al.1993). After the initial months to years, the oedema slowly vanishes and gradually atrophy becomes more and more prominent. The skin becomes increasingly vulnerable, thin and wrinkling, with prominently visible underlying vessels. When exposed to a cold environment, the skin becomes pronouncedly bluish. Band-like fibrous indurations may occur in the involved regions, usually in ulnar or tibial regions, or they may be nodular, preferably localised prepatellarly or next to the olecranon (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Müllegger 2004). In some cases of ACA, sclerotic lesions are clinically and histologically indistinguishable from localised scleroderma (morphea) or lichen sclerosus et atrophicus. About every tenth patient with typical inflammatory ACA also has a lichen sclerosus et atrophicus-like lesion (Asbrink and Hovmark 1987), and the histopathological picture of some of these patients is compatible with that of lichen sclerosus et atrophicus (Asbrink, Hovmark and Olsson 1986, Asbrink et al.1986). Peripheral nerves and joints are quite often involved in the regions of affected skin (Asbrink and Hovmark 1988). The majority of untreated patients with ACA have some kind of mostly mild or moderate neuropathy, as indicated by clinical and/or neurophysiological examination (Kristoferitsch et al.1988). Sensory and motor mononeuropathy or polyneuropathy or patchy dysaesthesia may develop at the site of the cutaneous lesions. Patients with ACA complain of hyperaesthesia/dysaesthesia, muscle cramps, muscle weakness and/or sensations of heaviness, mainly in the affected limb(s). Central nervous system (CNS) involvement in patients with ACA appears to be rare. In about one-fifth of patients with long-lasting ACA, subluxation and/or luxation of the small joints of hands or feet occur. A smaller proportion of patients with long-lasting disease show periosteal thickening of bones similar to dactylitis syphilitica in the late phase of syphilis (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986). Bursitis of the knee or elbow, epicondylitis, retro- or subcalcaneal bursitis and Achilles tendinitis may precede or accompany ACA (Asbrink and Hovmark 1987; Herzer 1993). The proper diagnosis of ACA is based on clinical, serological and histological criteria. Absence of IgG antibodies to B. burgdorferi s.l. in a patient with clinically suspected ACA requires reconsideration of the diagnosis because ‘seronegative’ ACA patients are almost non-existent (Kristoferitsch et al.1988; Asbrink, Hovmark and Weber 1993). Histological examination of the involved skin additionally consolidates the diagnosis. ACA lesions are infiltrated throughout the dermis with CD8+ and CD4+ T cells along with smaller numbers of B cells and abundant plasma cells (Müllegger et al.2007). Routine laboratory tests are usually in the normal range and thus not of substantial diagnostic help. The diagnosis of ACA can be further supported by the isolation of B. burgdorferi s.l. from lesional skin, which may be successful in about one-third of patients without previous antibiotic treatment (Ružić-Sabljić et al.2002). ACA should be considered as a possible diagnosis in a patient with bluish-red discolouration of a limb with or without swelling and/or atrophy (Müllegger 2004). Differential diagnoses or more often false interpretation of ACA skin lesions on the lower extremities are vascular insufficiency such as chronic venous insufficiency, superficial thrombophlebitis, hypostatic eczema, arterial obliterative disease, acrocyanosis, livedo reticularis, lymphoedema, ‘old skin’ or chilblains. Fibrous nodules may be misinterpreted as rheumatoid nodules and gout or even as erythema nodosum. Other skin manifestations of potential borrelial aetiology Scleroderma circumscripta and lichen sclerosus et atrophicus A borrelial aetiology of scleroderma circumscripta and lichen sclerosus et atrophicus, sclerotic skin lesions of unknown aetiology, has been implicated on the basis of humoral and cellular immune responses to B. burgdorferi s.l., on immunohistological findings and on demonstration of borrelial DNA in and isolation of B. burgdorferi s.l. from lesional tissue (Aberer et al.1987; Weber, Preac-Mursic and Reimers 1988; Breier et al.1999). However, proof of the aetiological role of B. burgdorferi s.l. in these skin disorders has not yet been established (Müllegger 2004). It should also be emphasised that sclerotic lesions that are clinically and histologically indistinguishable from localised scleroderma (morphea) or lichen sclerosus et atrophicus develop in about 10% of patients with typical inflammatory ACA (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Asbrink, Hovmark and Weber 1993). Cutaneous lymphoma Seropositivity, demonstration of borrelial DNA in 9 out of 50 (18%) of European patients with various types of primary cutaneous B-cell lymphoma and isolation of B. burgdorferi s.l. from skin lesions of two patients have suggested a possible association between primary cutaneous B-cell lymphomas and B. burgdorferi s.l. infection (Cerroni et al.1997; Kütting et al.1997). Further, the results of a case–control study in Denmark and Sweden suggest an association between B. burgdorferi s.l. infection and risk of mantle-cell lymphoma (Schöllkopf et al.2008). However, researchers from the USA did not find any such association in molecular or epidemiological studies (Munksgaard et al.2000; Wood et al.2001). Although the association has not been scientifically confirmed, the European Organization for Research and Treatment of Cancer and the International Society for Cutaneous Lymphoma suggest in a consensus paper that cutaneous marginal-zone lymphoma in European areas endemic for B. burgdorferi s.l. infection should be treated with antibiotics (Senff et al.2008). However, the efficacy of antibiotic treatment in borrelia-associated primary cutaneous marginal-zone lymphoma is poorly documented. Lyme neuroborreliosis LNB is the most common extracutaneous manifestation of Lyme borreliosis in Europe (Berglund et al.1995). LNB appears mostly early, during the first few weeks or months after infection, only rarely appearing late in the course of Lyme borreliosis. Early LNB typically shows lymphocytic meningitis and involvement of cranial and peripheral nerves. Case 6. A 43-year old farmer—who remembered several tick bites each year—became unwell in the middle of July. He suffered from myalgia, joint pain and mild headaches, was tired and occasionally very sleepy. At the end of September, after a short improvement for about 3 weeks, he developed chest pain, which expanded in extent during the first few days and became more and more intense. He reported an approximately 25 cm wide belt with a burning sensation over the upper part of the abdomen and lower part of the thorax that became worse during the night. It was hard for him to move because of the pain. He became impatient, agitated and experienced episodes of weeping for no obvious reason. He felt exhausted and totally without willpower. Problems were especially severe at night. For nearly 4 weeks, he was almost sleepless. There was no fever, no headache and no nausea. He visited his doctor several times but examinations revealed no abnormality. Sedatives and painkillers did not bring any relief. At the end of September, a day before admission to the hospital, he noticed that he was not able to close his left eye, to raise his left eyebrow, to frown on the left side of his forehead and that the left side of his mouth was not moving properly. On admission to hospital, the patient moved slowly and very carefully; he was in distress and seemed to be exhausted. He had left-sided peripheral facial palsy, but no other significant abnormality was found. Meningeal signs were not expressed. Results of the blood tests were within normal limits. CSF was clear, open pressure was normal. CSF leukocyte count was 114 × 106/l (96% lymphocytes), protein concentration 0.64 g/l (normal < 0.45 g/l), while concentrations of CSF and blood glucose were in normal range (3.6 and 4.9 mmol/l, respectively). Comment: Typical presentation of meningoradiculoneuritis (Gadin-Bujadoux-Bannwarth) syndrome with radicular pain, peripheral facial palsy and lymphocytic pleocytosis. The syndrome has been known in Europe for more than 90 years, i.e. well before the discovery of Lyme disease in the USA. Borrelial aetiology was definitely established by the isolation of B. burgdorferi s.l. from CSF. Meningoradiculoneuritis is the most prominent clinical manifestation of LNB in adult patients in Europe. It begins gradually with increasing pain, later on accompanied by palsies and other neurological signs and symptoms that will, if untreated, not diminish for many weeks (Kristoferitsch, Spiel and Wessely 1983; Pachner and Steere 1985; Kristoferitsch 1989, 1991; Hansen 1994; Stanek et al.2012; Ogrinc et al.2016) (Fig. 8). Radicular pain is the most pronounced clinical symptom of meningoradiculoneuritis; it is usually severe and most intense during the night. In children isolated meningitis and peripheral facial palsy are more common than in adults. In addition, involvement of motor nerves may lead to paresis (Kristoferitsch 1991; Hansen 1994; Hansen, Crone and Kristoferitsch 2013). Figure 8. View largeDownload slide Onset, duration and intensity of signs/symptoms in the spontaneous untreated course in patients with meningopolyneuritis (Kristoferitsch 1989). Figure 8. View largeDownload slide Onset, duration and intensity of signs/symptoms in the spontaneous untreated course in patients with meningopolyneuritis (Kristoferitsch 1989). Up to 10% of European patients with untreated meningopolyneuritis develop signs and symptoms of disseminated encephalomyelitis that may in some respects resemble those seen in multiple sclerosis (Kristoferitsch 1991). Case 7. A 13-year-old boy felt completely well during the first few weeks after a tick bite. However, 6 days after the bite he noticed a small redness at the site of the bite on his right thigh. In the next 2 weeks, the redness gradually increased in size to reach diameter of about 30 × 20 cm, clearing centrally and becaming ring-like. After 3 weeks, it spontaneously disappeared. Six weeks after the tick bite, headaches, nausea, vomiting and low fever appeared. The patient became sensitive to light and had pain when moving the eyes. The headache was predominantly frontal and varied in intensity. Five days later, he was admitted to the hospital due to the suspicion of aseptic meningitis. The only abnormalities found on admission were that he looked tired, had a body temperature of 38.3°C and had mildly expressed nuchal rigidity. CSF examination revealed findings consistent with lymphocytic meningitis: 165 × 106/l leukocytes (85% lymphocytes), protein concentration of 0.76 g/l, glucose in CSF 2.8 mmol/l and blood sugar 5.4 mmol/l. The diagnosis of borrelial meningitis was indicated by the history of EM and was further supported by the demonstration of serum antibodies to B. burgdorferi s.l. as well as detection of intrathecal synthesis of specific antibodies. The patient was treated with doxycycline 100 mg bid for 14 days and had an uneventful recovery. Comment: Characteristic presentation of borrelial CNS involvement in a child. Patients with borrelial meningitis usually suffer from mild intermittent headache, resembling relatively mild but unusually protracted viral meningitis with intermittent improvements and deterioration. Excruciating headache occurs exceptionally. In adult patients, fever, nausea and vomiting and meningeal signs are usually absent (Kristoferitsch 1991; Hansen 1994; Stanek and Strle 2003). In contrast, there is an abnormal CSF finding: lymphocytic pleocytosis up to several hundred × 106 cells/l. Protein concentration is normal or slightly to moderately elevated; glucose concentration is usually normal or mildly depleted. Case 8. An 11-year-old girl was bitten by a tick while collecting blueberries in June. No skin lesion developed at the site of the bite. On one evening, 5 weeks later, tingling and a ‘wooden’ sensation on the left side of her face occurred, and when she woke up on the next morning, she couldn’t close her left eye, nor raise the left eyebrow nor wrinkle the skin of her left forehead, she was not able to whistle and her left oral angle was immobile. Three days later, similar changes occurred on the other side of her face. She had no headache, no vomiting nor fever. At examination bilateral peripheral facial palsy was established. Meningeal signs were absent; basic laboratory blood tests were in normal range. CSF examination revealed normal opening pressure. CSF was clear with 108 × 106/l leukocytes (84% lymphocytes); the protein and glucose concentrations were normal. She was treated with i.v. ceftriaxone for 14 days and completely recovered after 3 months. Comment: In about half of patients with borrelial meningitis, peripheral facial palsy develops. In some patients, the paralysis is bilateral; in such cases, pareses usually do not appear at the same time. Patients often report a tingling sensation on the affected side and pain around the ear or jaw. Disorder of taste is rare (facial nerves are usually affected distally from the branching of the chorda tympani nerve). Palsies are of sudden onset, lasting from a few days to several months (average 8 weeks); they usually heal spontaneously and completely. Any cranial nerve may be affected in LNB but facial nerves are most frequently involved, resulting in unilateral or bilateral peripheral facial palsy (Kristoferitsch 1991; Halperin and Golightly 1992; Hansen 1994; Christen 1996; Lotrič-Furlan et al.1999; Eiffert et al.2004; Hansen, Crone and Kristoferitsch 2013). In an endemic region, peripheral facial palsy is associated with Lyme borreliosis in about 20% of adult patients and 25% of children (Lotrič-Furlan et al.1999; Strle and Stanek 2009). Lymphocytic pleocytosis is often seen in patients with borrelial peripheral facial palsy, although signs or symptoms of meningitis are absent (Lotrič-Furlan et al.1999). Borrelial peripheral facial palsy responds very well to antibiotic treatment but prognosis is also good in untreated patients (Pachner and Steere 1985; Hansen 1994). However, in clinical and neurophysiological examination, mild sequelae were found in about half of Swedish children who had borrelial peripheral facial palsy 3–5 years earlier (Bagger-Sjobak et al.2005). Results from another Swedish study showed that about 20% of children with acute facial palsy have permanent mild-to-moderate dysfunction of the facial nerve without other neurological symptoms or health problems, and that antibiotic treatment seems to have no correlation with the clinical outcome of peripheral facial palsy (Skogman, Croner and Odkvist 2003). Shortly after onset of neurological symptoms, intrathecal synthesis of antibodies may not be detectable and CSF pleocytosis may be absent especially in children with isolated facial palsy (Millner et al.1989). Involvement of most other cranial nerves has been described, particularly nervus oculomotorius, n. abducens and n. vestibulocochlearis. Clinical diagnosis of LNB is best supported by a preceding or accompanying EM, which is the case in 34–64% of patients with meningopolyneuritis (Stiernstedt et al.1985; Kristoferitsch 1989; Pfister, Kristoferitsch and Meier 1993; Strle et al.2006; Ogrinc et al.2016). A close topical association between the cutaneous region of the tick bite, subsequent EM and the radicular lesion has been established in European patients (Kristoferitsch et al.1983; Pfister et al.1987). An unusual manifestation of LNB is pseudotumour cerebri which is seen primarily in children (Steenhoff et al.2006; Feder 2008). In the USA, the most common LNB disorder is lymphocytic meningitis. Encephalitis resulting from a B. burdorferi s.l. infection seems to be extremely rare (Halperin 2008). Subtle encephalopathy has been reported predominantly by American authors (Logigian, Kaplan and Steere 1990). LNB in Europe is most often caused by B. garinii, less frequently by B. afzelii and B. burgdorferi and only exceptionally by other genospecies (Fig. 2) such as B. valaisiana, B. bissettii or yet unidentifiable species (Hitzo-Teufel et al.1996; Peter et al.1997; Strle et al.1997, 2006; Lebech et al.1998; Ryffel et al.1999; Ružić-Sabljić et al.2001; Ornstein et al.2002; Fingerle et al.2008; Ogrinc et al.2013, 2016). The clinical presentation of patients with a CSF culture-proven B. garinii LNB is different from that of patients with a B. afzelii LNB (Strle et al.2006). Borrelia garinii causes what, in Europe, is diagnosed as typical early LNB (i.e. painful meningoradiculoneuritis or Bannwarth syndrome), whereas the clinical features of CNS involvement associated with B. afzelii are much less specific and more difficult to diagnose since these patients rarely report radicular pains and have express meningeal signs. In contrast to the B. garinii group, the large majority of the B. afzelii group did not fulfill European criteria for LNB (Strle et al.2006). The findings of the study might indicate that, although B. afzelii is able to pass through the blood–brain barrier, it has restricted capability to initiate a substantial inflammation of the CNS. The significance of this genospecies in LNB remains to be elucidated. Histopathological findings in the CNS are limited. In peripheral neuropathy accompanying ACA, lymphocytes and plasma cells are present around blood vessels in the perineurium, with occasional sparse lymphocytes in vessel walls which show no signs of necrosis but may become thickened and obliterated, thrombosis may develop (de Koning and Duray 1993). Fibres within the nerve eventually lose myelin. The most striking finding is axonal degeneration (Kristoferitsch et al.1988; de Koning and Duray 1993; Hansen, Crone and Kristoferitsch 2013). Late LNB is most probably very rare. The only exception is peripheral neuritis in association with ACA. Peripheral neuritis occurs in more than half of patients with long-lasting ACA (Kristoferitsch 1991, 1993). Careful sight of the literature suggests that peripheral neuritis without ACA is an extremely rare condition, if it exists at all (Hansen, Crone and Kristoferitsch 2013; Wormser et al.2017). The diagnosis of early LNB should be based on clinical characteristics, the presence of lymphocytic pleocytosis and demonstration of CNS borrelial infection, as evidenced by intrathecal production of antibodies against B. burgdorferi s.l. (Wilske et al.1986; Brouqui et al.2004; Aguero-Rosenfeld et al.2005; Strle et al.2006; Mygland et al.2010). Isolation of borreliae from the infection site would be the most reliable method of diagnosing LNB, but unfortunately isolation from CSF or demonstration of borrelial DNA in CSF samples is limited by low sensitivity. Further, procedures for DNA detection are not standardised and may give false-positive results (Wilske et al.2000; Brouqui et al.2004; Aguero-Rosenfeld et al.2005; Strle et al.2006; Cerar et al.2008; Stanek et al.2012). In everyday European clinical practice, demonstration of intrathecally synthesised antibodies to B. burgdorferi s.l. has been established for the diagnosis of LNB. However, physicians should be aware that intrathecal synthesis may not be demonstrable shortly after the onset of LNB (Hansen 1994; Aguero-Rosenfeld et al.2005; Strle et al.2006; Cerar et al. 2010; Stanek et al.2011, 2012, 2014). In the presence of strong clinical evidence together with CSF pleocytosis and preceding EM, the clinician should stay with the clinical diagnosis despite absence of proof of intrathecal antibody production. This may be demonstrable in later samples. A reliable diagnosis of a borrelial infection involving the peripheral nervous system strongly depends upon the concomitant presence of LNB and/or some other manifestation of Lyme borreliosis such as EM or ACA. Differential diagnosis comprises a list for each main manifestation of LNB, such as meningitis, radiculoneuritis, cranial nerve involvement and so forth. However, an exact medical history and meticulous clinical examination can often substantially narrow the possibilities. Lyme carditis Case 9. A 28-year-old previously healthy housewife was bitten by a tick in the middle of May. No skin lesion developed at the site of the bite. At the end of May, intermittent migratory myalgia and arthralgia appeared and a month later burning belt-like pain in the middle of the chest emerged; the pain was very severe and nearly unbearable at night. The patient was not able to sleep and was suicidale due to pain. She also had difficulties with concentration and thinking and was afraid of making mistakes when performing even the simplest daily tasks. She did not have headache, nausea or fever. On 27 August, she woke up with pressing retrosternal pain spreading to the neck. She was dizzy when standing up but dizziness disappeared when she lay down. She was examined at the emergency department and admitted to hospital. ECG showed second degree atrio-ventricular (A-V) block. Ultrasound examination of heart revealed no substantial abnormalities. In the evening of the next day, bradycardia (34/min) appeared; complete heart block with narrow QRS complexes was established and a transitory pacemaker was inserted. In the following 2 days, the patient had changing third to second degree A-V blocks. On 31 August, the block was predominantly of second degree and occasionally also of first degree, and on 1 September only first degree A-B block was registered. In the following week, P-Q interval shortened from 320 ms to normal values. The further clinical course was smooth and the outcome was uneventful. From the second day of hospitalisation, the patient was treated with ceftriaxone 2 g i.v./day for 14 days. The diagnosis of Lyme carditis was substantiated by high levels of IgG serum antibodies to B. burgdorferi s.l., and by demonstration of coexisting LNB (CSF examination, performed due to radicular pains, showed lymphocytic pleocytosis and intrathecal synthesis of IgG antibodies to B. burgdorferi s.l.). Comment: A typical course and outcome of Lyme carditis. In patients with suspected Lyme carditis, the diagnostic approach should include active search for other manifestations of Lyme borreliosis (such as EM and LNB) and exclusion of other explanations for cardiac abnormalities. Heart involvement related to a borrelial infection usually presents with the acute onset of varying degrees of intermittent atrioventricular (A-V) heart block, sometimes in association with clinical evidence of myopericarditis (Steere et al.1980; McAlister et al.1989). It is often coincident or following other features of Lyme borreliosis such as EM, LNB or arthritis (Steere et al.1980; Van der Linde 1991). The frequency of heart involvement in relation to the other manifestations of Lyme borreliosis appears to be very low (Rubin et al.1992; Sigal 1995; Wormser et al.2006; Steere et al.2016). No evidence of carditis was found among 233 cases with definite Lyme borreliosis in two prospective studies evaluating a recombinant OspA vaccine in the USA (Sigal et al.1998; Steere et al.1998). In an epidemiological study in southern Sweden, only 7 of 1471 (0.5%) patients with Lyme borreliosis had carditis (Berglund et al.1995) and at the Ljubljana Lyme borreliosis clinic, where about 600–1000 patients with different manifestations of Lyme borreliosis are diagnosed each year, Lyme carditis was diagnosed in less than 0.5% of cases (unpublished data). Histopathology shows interstitial infiltrates of lymphocytes and plasma cells involving the myocardium, pericardium and endocardium. Muscle fibres are usually intact (Steere et al.1980; Reznick et al.1986). The heart conducting system may show localised oedema and slight lymphocytic infiltration of sinoatrial and A-V nodes, focal oedema in the bundle of Hiss, fibrotic lesions, and vasculitis of small and large intramyocardial vessels (de Koning and Duray 1993; Fish, Pride and Pinto 2008). Spirochaetal forms have been found in endomyocardial biopsy (de Koning et al.1989), and borreliae have been cultured from biopsy specimens (Stanek et al.1990). Lyme carditis occurs between June and December, usually within 2 months after the onset of infection, men being affected more often than women (Steere et al.1980; McAlister et al.1989). The most common complaints in Lyme carditis include mild dizziness, syncope, dyspnoea, palpitations and/or chest pain. The prognosis is usually favourable (Sigal 1995). Hospitalisation is needed for patients with first-degree A-V block with P-Q interval longer than 0.30 s, second- or third-degree A-V blocks, quickly changing A-V blocks or haemodynamically precarious arrhythmias (van der Linde 1991). In a case of complete heart block, insertion of a temporary heart pacemaker may be life saving. Diffuse ST segment and T wave changes on surface electrocardiograms were noted in the majority of a first series of patients with Lyme carditis (Steere et al.1980). In most cases, myocardial dysfunction is mild and self-limited (Steere et al.1980; Midttun et al.1997). The isolation of B. burgdorferi s.l. from an endomyocardial biopsy specimen of a 54-year-old man with a 4-year history of dilated cardiomyopathy (Stanek et al.1990) inspired the hypothesis of a causative role in chronic heart failure. However, there is as yet no convincing evidence of such an association. Diagnosis of Lyme carditis should be based on established conduction disturbances (electrocardiographic and/or electrophysiological findings) and/or myo(peri)carditis (demonstrated pathohistologically in endomyocardial biopsy specimens, or suggested by electrocardiographic, echocardiographic and/or MRI findings) (Strle and Stanek 2009). The diagnosis also requires corroboration by demonstration of borrelial infection; in practice the presence of typical manifestation(s) of Lyme borreliosis such as EM or LNB is the most reliable. A diagnosis of Lyme carditis should be further substantiated by the absence or exclusion of other (obvious) explanations for cardiac abnormalities. Lyme arthritis Case 10. A 56-year-old accountant developed migratory myalgias and arthralgias in mid of September that he attributed to pronounced physical activities during the previous months. At the beginning of October, he woke up with severe pain in the right knee. The joint was heavily swollen, warm, skin colour was normal. The pain, which was quite severe at rest, deteriorated with movement. He was treated with anti-inflammatory drugs. Five days later, and 2 days before right knee swelling vanished, effusion of his left knee appeared, and somewhat later the right ankle became painful and swollen. The duration of attacks of individual joint involvement was 5–14 days. Basic laboratory tests disclosed normal results with the exception of moderately elevated C-reactive protein (CRP) concentration (56 mg/l). Synovial fluid examination of the right knee revealed elevated leukocyte counts (48 × 109/l) with a predominance of polymorphonuclear leukocytes (74%). Synovial fluid culture was negative for the presence of bacteria, and no crystals were found. However, the patient had high serum IgG antibody levels to B. burgdorferi s.l., and the presence of borrelial DNA in the synovial fluid was demonstrated by PCR. The patient was treated with doxycycline 100 mg bid for 4 weeks. Before the end of antibiotic therapy, attacks of arthritis vanished and later on he only occasionally had mild-to-moderate arthralgias of large joints. Comment: A characteristic course and outcome of Lyme arthritis. Lyme arthritis is mostly monoarticular or oligoarticular, typically involving the knee. The frequency of this manifestation is about 10% of all Lyme borreliosis manifestations according to studies in the USA (Steere, Schoen and Taylor 1987; Steere 1989; Gerber et al.1996; Sigal et al.1998; Steere 2001; Krause et al.2002). In Europe, the aetiological relationship of certain cases of arthritis to a B. burgdorferi s.l. infection was not considered before a link was established in the USA. Nevertheless, European dermatological literature had described a relationship between joint and bone abnormalities and ACA long before, as emphasised by the term ‘akrodermatitis atrophicans arthropathica’ (Gans and Landes 1952), and joint symptoms had been mentioned in case reports on erythema chronicum migrans and lymphocytic meningitis (Bannwarth 1941; Schaltenbrand 1949; Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Herzer 1993). However, Lyme arthritis has ever since been considered a less common manifestation in Europe than in the USA. Seven per cent of 1491 patients diagnosed with Lyme borreliosis in a study from southern Sweden had Lyme arthritis (Berglund et al.1995), and about 3% of patients who presented with Lyme borreliosis at the outpatients clinic in Ljubljana had clinical arthritis (see Fig. 4). The isolation rate of borreliae from joint fluid and synovia is very low; thus, data on the infecting agent are based predominantly on molecular detection of borrelial DNA in synovial fluid or synovial tissue. The genospecies identified in Lyme arthritis cases in Europe were B. burgdorferi in three cases from the Netherlands (van der Heijden et al.1999), and B. burgdorferi in nine cases and B. garinii in two cases from France (Jaulhac et al.2000; Limbach et al.2001). The synovial fluid from 13 of 20 patients with the diagnosis of Lyme arthritis in Germany was processed for borrelial DNA by OpsA typing and revealed B. burgdorferi in 27%, B. afzelii in 33% and B. garinii in 40% (Vasiliu et al.1998), with no predominance of any particular genospecies. Similar results were obtained in another study from Germany where B. burgdorferi and B. garinii were each detected in the synovial fluid of three patients and B. afzelii was detected in one (Eiffert et al.1998). B. burgdorferi was cultivated from the synovial fluid of an Austrian patient when Lyme arthritis developed following an autologous chondrocyte transplant (Marlovits et al.2004). B. bavariensis was detected in the synovial fluid of the knee and ankle joint of an 11-year-old boy who suffered from intermittent arthritis over 5 years (Markowicz et al.2015). Acute arthritis results from Borrelia-induced infiltration of mononuclear cells into the synovial tissue and the accumulation of neutrophils, immune complexes, complement and cytokines in the synovial fluid. In untreated Lyme arthritis, host factors involved may include autoantigens like endothelial cell growth factor and apolipoprotein B-100, arthritogenic factors such as TLR2 and MyD88, adhesion molecules P66 that bind the extracellular matrix, decorin-binding proteins A and B, Bgp and BKK, T and B-cell responses to annexin A2, and annexin A2 autoantibodies (Coburn, Fischer and Leong 2005; Guerau-de-Arellano and Huber 2005; Drouin et al.2013; Londoño et al.2014; Crowley et al.2015; Pianta et al.2015). In addition, matrix metalloproteinases may be involved in the pathogenesis of erosive processes in the joint in long-standing infection and possibly also in antibiotic-refractory arthritis (Hu et al.2001; Behera et al.2005; Crowley et al.2016). Excessive TH17 responses may be disadvantageous by contributing to autoimmune responses associated with antibiotic-refractory Lyme arthritis (Strle et al.2017). Persistent or antibiotic-refractory Lyme arthritis may be observed in a subset of patients who have already received standard antibiotic treatment. Models for the immune-pathogenesis proposed comprise persistent infection, T-cell epitope mimicry and bystander activation of T cells. However, none of these has enabled a complete explanation for all patients. The aetiology is most probably multifactorial and may vary from patient to patient (Steere and Glickstein 2004; Puius and Kalish 2008). The main and the most important joint manifestation of Lyme borreliosis is arthritis. Arthralgia may precede, accompany or follow arthritis but may sometimes be the only rheumatic manifestation of Lyme borreliosis. Indicative of Lyme arthritis in Europe are the succession or coexistence of intermittent attacks of musculoskeletal pain and arthritis (Herzer 1993). In a subset of patients, episodes of severe pain in joint and periarticular sites may precede arthritis for several weeks or months, or may precede and continue after arthritis, or may develop with arthritis. Episodes of arthralgias may alternate with attacks of arthritis. Large joints are predominately affected but also small joints in an often migratory pattern; however, involvement of only small joints is very rare. Mostly only one or two sites are affected at any one time (Herzer 1993). In the early studies, arthralgias were reported in 48% of patients with EM in North America (Steere et al.1983a) but in only 22% at the most in European patients (Weber and Neubert 1986). In a later study, 40% of patients with B. burgdorferi EM in New York State reported arthralgias prior to treatment, whereas only 27% of Slovenian patients with B. afzelii EM complained about arthralgias (Strle et al.1999). In another study from Ljubljana/Slovenia in 231 patients with culture-confirmed EM, only 12% reported arthralgias that were mild to moderately severe (Strle et al.1996b). Arthralgias usually vanish during the first few weeks after standard treatment (Cerar et al. 2010). The incubation period for Lyme arthritis, from tick bite to clinical manifestation, cannot be easily assessed. In patients from North America who had EM without antibiotic treatment and were followed up for years, arthritis occurred from 4 days to 2 years after onset of infection, with a mean of 6 months (Steere, Schoen and Taylor 1987). In a European series of patients, the period from tick bite or EM to the onset of arthritis ranged from 10 days to 16 months, with a mean of 3 months (Herzer 1991). Lyme arthritis can be preceded or accompanied by other manifestations of Lyme borreliosis. EM before Lyme arthritis has been reported in 25% of patients in the USA (Steere et al.1977b). In patients in Germany, EM has been reported in 32%, LNB in 22%, ACA in 8% and carditis in 1.5% (Herzer 1993). Results of a prospective epidemiological study of Lyme borreliosis in southern Sweden showed that of 98 patients diagnosed with Lyme arthritis (7.5% of all cases), 65 presented with arthritis alone; in the remaining patients, arthritis was associated with EM in ten, LNB and ACA in eight each, and borrelial lymphocytoma in one. Six patients with arthritis had two additional main manifestations of Lyme borreliosis (Berglund et al.1995). For clinical diagnosis, it should be considered that Lyme arthritis usually consists of intermittent attacks of inflammation of one or a few large joints and is often preceded by intermittent migratory joint pain. Joint involvement is usually asymmetric, the onset of arthritis is acute and with effusion, and skin over the affected joint is warm but of normal colour (Steere, Schoen and Taylor 1987). The knee is most often involved. Shoulder, ankle, elbow, temporomandibular joint, wrist and hip are affected in the range of 28%–43%, and metacarpophalangeal, proximal interphalangeal, distal interphalangeal and metatarsophalangeal joints are involved in 11% (Steere, Schoen and Taylor 1987). Similarly, in the European series of 65 patients, involvement of the knee was by far the most common, followed by ankle, wrist, finger, toe and elbow; heel swelling was found in 9% and dactylitis in as many as 23% (Herzer 1991, 1993). In the patients with knee involvement alone, Baker cysts were found in 50%. However, some patients with pronounced knee effusions have only mild pains (Steere, Schoen and Taylor 1987). Joint inflammation usually lasts a few days to weeks, sometimes several months (Steere, Schoen and Taylor 1987). The course of Lyme arthritis is usually recurring and may continue for several years. In the beginning, the attacks of arthritis are more frequent and short, later they may be more prolonged and about 10% of patients develop chronic arthritis with duration of a year or longer (Steere, Schoen and Taylor 1987; Rees and Axford 1994). Fatigue, malaise, low fever or night sweats may accompany Lyme arthritis in a small proportion of patients (Herzer 1991, 1993). Routine laboratory parameters are often completely normal in Lyme arthritis. Concentration of CRP is usually in the normal range. The pronounced elevation of laboratory inflammation parameters in a patient with arthritis points strongly against Lyme arthritis. Some patients have slightly elevated counts of white blood cells, and some elevated serum IgM. Cryoglobulins and circulating immune complexes may be present. Rheumatoid factors and antinuclear antibodies are usually negative. Synovial fluid shows elevated white cell counts with a range of 0.5–110 × 109 cells L−1, with predominance of polymorphonuclear leukocytes up to about 80% (Steere et al.1977a,b; Steere, Schoen and Taylor 1987; Herzer 1991, 1993; Rees and Axford 1994). Total protein concentration commonly ranges from 3.5 to 5.6 g L−1 (Steere et al.1977a,b; Herzer 1991; Rees and Axford 1994). Cryoglobulins and abnormal C1q binding consistent with antigen–antibody complexes are commonly present in synovial fluid (Hardin and Steere 1979; Steere et al.1979). Specific radiographic findings for Lyme arthritis have not been reported (Lawson and Steere 1985). Serum IgG antibodies to B. burgdorferi s.l. are almost always present in high titres in patients with Lyme arthritis, negative IgG serology basically ruling the diagnosis out (Aguero-Rosenfeld et al.2005; Puius and Kalish 2008). Serological investigation of synovial fluid is of no value because of the absence of a blood–synovial barrier; IgG antibody concentration in serum and synovial fluid will be the same. What would additionally support the diagnosis of Lyme arthritis is the demonstration of borrelial DNA in synovial fluid or in synovial tissue. Diagnosis of Lyme arthritis is based on the medical history (other manifestations of Lyme borreliosis such as EM, LNB or ACA), clinical features, laboratory findings, exclusion of other causes of arthritis and demonstration of serum IgG antibodies to B. burgdorferi s.l. (Nadelman and Wormser 1998; Strle 1999a; Steere 2001; Stanek and Strle 2003). One should nevertheless be aware that IgG seropositivity is not diagnostic for Lyme arthritis as it does not inform about active or past infection nor about the location of the disease process. Thus, PCR detection of borrelial DNA in synovial tissue or synovial fluid should always be attempted since its sensitivity is high, at up to 85% (Snydman et al.1986; Nocton et al.1994; Eiffert et al.1998; Vasiliu et al.1998; van der Heijden et al.1999; Jaulhac et al.2000; Aguero-Rosenfeld et al.2005; Wormser et al.2006). The differential diagnosis of Lyme arthritis includes inflammatory rheumatic diseases, bacterial (septic) arthritis, viral arthritis and crystal-induced arthritis (Steere, Schoen and Taylor 1987; Herzer 1991; Rees and Axford 1994). Other differential diagnoses include psoriatic arthritis, early rheumatoid arthritis and systemic lupus erythematosus in patients who have borrelial antibodies in serum. Musculoskeletal pain in Lyme borreliosis may be mistaken for psychogenic rheumatism or fibromyalgia. However, fibromyalgia is characterised by more generalised chronic pain and by symmetric tender points, and thus more often fibromyalgia in seropositive persons is often wrongly diagnosed as Lyme borreliosis (Herzer 1991). Eye involvement Eye involvement in the course of Lyme borreliosis appears to occur very rarely and is associated with EM, LNB or Lyme arthritis, although it can be the sole manifestation of the disease (Steere 1989; Strle 1994; Mikkila et al.2000). Often, the clinical ocular features may not be recognised (Karma et al.1995; Mikkila et al.1999; Colucciello 2001). Since human intraocular material is usually unavailable, serology remains the main diagnostic aid with all its interpretation problems. Onset of eye involvement is difficult to assess; the interval from EM may range from a few days to years. Conjunctivitis is apparently an early ocular manifestation whereas keratitis appears late in the course of Lyme borreliosis (Schönherr and Strle 1993). Primary borrelial-induced inflammation of the eye includes conjunctivitis, keratitis, iridocyclitis, retinal vasculitis, chorioiditis, optic neuropathy, episcleritis, panuveitis and panophthalmitis. Secondary effects are results of extra-ocular manifestations of borrelial infection, including pareses of certain cranial nerves, pseudotumour cerebri and orbital myositis (Steere et al.1985; Karma et al.1995; Mikkila et al.1999; Colucciello 2001; Carvounis, Mehta and Geist 2004; Mahne et al.2015). Inflammation of the eyes may lead to severe impairment or even complete loss of vision (Steere 1989; Schönherr and Strle 1993; Mikkila et al.1999, 2000; Colucciello 2001). The frequency of conjunctivitis associated with EM was 11% in patients in the USA, whereas in Europe the proportion was between 4% and 5% in Slovenian patients (Schönherr and Strle 1993). In later published cases of EM, conjunctivitis was reported only rarely or not mentioned at all. Ocular inflammation was diagnosed in 4% of children and adolescents who suffered from Lyme arthritis; the eye involvement comprised keratitis, anterior uveitis and uveitis intermedia (Huppertz, Munchmeier and Lieb 1999). Intraocular involvement resulting from borrelial infection has been described in 19 European patients. The borrelial aetiology was primarily based on seropositivity. Twelve of the patients had chorioiditis, three neuroretinitis, two bilateral retinal vasculitis, one bilateral iridocyclitis and one keratitis (Schönherr and Strle 1993). Other objective manifestation(s) of Lyme borreliosis were present in nine of these patients. Diagnosis of borrelial eye involvement should be based on medical history, complete physical (not only ophthalmological) examination and demonstration of borrelial infection. The differential diagnosis is broad (Schönherr and Strle 1993; Mikkila et al.2000; Strle and Stanek 2009; Mahne et al.2015). Other rare manifestations attributed to Lyme borreliosis A possible causative role of B. burgdorferi s.l. has been discussed for progressive facial hemiatrophia and eosinophilic fasciitis, also known as Shulman syndrome (Stanek et al.1987a,b; Granter et al.1994; Hashimoto et al.1996). In addition, there are case reports on patients with myositis (Reimers et al.1993), dermatomyositis (Horowitz et al.1994; Hoffmann et al.1995), nodular fasciitis (Schnarr et al.2002), panniculitis (Viljanen et al.1992) and osteomyelitis (Oksi et al.1994). There are also reports on the effect on individual organs or organ systems such as liver, lymphatic system, respiratory tract, urinary tract and genitalia (Steere 2001), but proof of the existence of such involvement in humans is weak. Lyme borreliosis during pregnancy There are no precise data on the natural course and outcome of Lyme borreliosis during pregnancy, but there is general acceptance that there are no substantial differences between pregnant and non-pregnant women with Lyme borreliosis, and that pregnant women treated for Lyme borreliosis have an outcome similar to women in the corresponding adult population (Maraspin and Strle 2009). Although it is well known that B. burgdorferi s.l. may be present in the blood early in the course of Lyme borreliosis, the consequences of this for the fetus are not clear cut (Maraspin et al.2011). In utero transmission of B. burgdorferi s.l. during pregnancy, resulting in fetal involvement, has been reported in humans (Schlesinger et al.1985; Markowitz et al.1986; MacDonald, Benach and Burgdorfer 1987; Weber, Preac-Mursic and Reimers 1988) and in animals such as cows, horses, dogs and mice (Gustafson et al.1993; Silver et al.1995). Nevertheless, reports of fetal involvement in humans are limited to the description of single cases, and in some articles the proof of borrelial infection is imprecise by present standards. There are also no reliable studies on the outcome of Lyme borreliosis after treatment as for the non-pregnant population. The only published prospective study on treatment of Lyme borreliosis during pregnancy is a report on 58 consecutively enrolled patients treated for EM with ceftriaxone 2 g daily for 14 days (Maraspin et al.1996) and its extension with the addition of 47 further patients (Maraspin et al.1999a). According to these two reports, none of the 105 consecutive pregnant women so treated for EM developed any subsequent manifestation of Lyme borreliosis, and the outcome of their pregnancies was analogous to the outcome in pregnant women without Lyme borreliosis. The majority of patients treated for EM (93/105, 88.6%) gave birth at term to healthy babies with normal later psychomotor development. The other 12 (11.4%) pregnancies ended with abortion in two cases, preterm delivery in six cases and congenital abnormalities in four babies delivered at term. No causal relationship with borrelial infection was established in any of these 12 cases and in several of them acceptably reliable alternative explanations were found for the unfavourable outcomes (Maraspin et al.1996,1999a). Lyme borreliosis in an immunocompromised host Information on the course and outcome of B. burgdorferi s.l. infection in immunocompromised patients is limited. There is one comparative study available on the course and outcome of typical EM in 67 adult patients with underlying immune-compromised conditions and in 67 previously healthy age- and sex-matched individuals with EM. The duration of EM after starting antibiotic treatment was similar in the two groups, but early disseminated borrelial infection before treatment and treatment failure were found more often in immunocompromised patients than in the control group. The two groups of patients were treated with the same antibiotic regimen. Re-treatment was required in 19% of immunocompromised patients but in only 7% of patients in the control group. However, both groups had a favourable outcome of borrelial infection after 1 year (Maraspin et al.1999b). With respect to the heterogeneity of causes for immune compromisation, it appeared that the likelihood of developing disseminated infection or treatment failure may be higher among patients with haematological malignancies. It was concluded that although in the majority of immunocompromised patients with EM the management can be the same as in immune-competent patients with early Lyme borreliosis, more aggressive initial antibiotic treatment might be appropriate for some subgroups of patients with altered immunity, such as those with haematological malignancy (Maraspin et al.1999b). A more recent study on 53 patients with EM and underlying hematological malignancy revealed that disseminated early Lyme borreliosis and treatment failure were diagnosed in 7/53 (13.2%) of patients with haematological malignancy, but in 0/106 immunocompetent patients, that the complications were limited to patients with underlying lymphoid neoplasm (complications were present in 7/41 patients with lymphoid neoplasm and in 0/12 with underlying myeloid neoplasia) and that they were associated with receiving immunosuppressive drugs. However, again, the outcome after 1 year was excellent, indicating that the antibiotic treatment approach as used in immunocompetent patients with EM is effective in patients with underlying haematological malignancy (Maraspin et al.2015). In another trial, the outcome of treatment of EM was studied in 33 patients immunosuppressed for several reasons and in 75 otherwise healthy patients with EM. The two groups were matched for sex, age and antibiotic therapy. Comparison did not reveal any significant difference between the two groups. The authors concluded that immunosuppression apparently does not influence clinical presentation, response to therapy or production of antibodies to B. burgdorferi s.l. in patients with EM. Thus, it is not necessary to treat immunosuppressed patients with EM differently from immunocompetent patients (Fürst et al.2006). The fourth report is on six adult recipients of solid-organ transplants who had chronic drug-induced immunosuppression and presented with solitary EM. All these patients had a localised EM and a mild and smooth course of illness, as well as a favourable outcome after treatment with the same antibiotic regimens as used for immunocompetent patients (Maraspin, Ruzic-Sabljic and Strle 2006). Chronic Lyme borreliosis and ‘chronic Lyme’ Chronic Lyme borreliosis exists in Europe. However, the designation should be reserved for patients with objective manifestations of late Lyme borreliosis, caused by persistent infection with B. burgdorferi s.l. These patients typically present with ACA, chronic arthritis and very rarely with chronic LNB without ACA. The term chronic Lyme borreliosis should not be misused or erroneously used for symptoms of unknown cause, nor for well-defined illness unrelated to borrelial infection but with antibodies against B. burgdorferi s.l., nor for symptoms of unknown cause with antibodies against B. burgdorferi s.l. but no reliable history of Lyme borreliosis, and not for post-Lyme borreliosis syndrome (Wormser et al.2006; Feder et al.2007; Marques 2008). Aspects of laboratory diagnosis in Lyme borreliosis According to the principles of medical microbiology, the specific aetiology of any infectious disease is usually best determined by direct detection of the agent from the site of infection. Without this and without a specific marker obtained by clinical laboratory methods, full proof of the borrelial aetiology of any of the described disorders in Lyme borreliosis will not be possible. Will such an approach be straightforward in suspected Lyme borreliosis? At present, the clinical laboratory cannot confirm Lyme borreliosis from routine blood values. CRP values and white blood cell counts are usually in the normal range (Nadelman and Wormser 1998; Strle 1999a,b; Steere 2001; Stanek and Strle 2003; Strle and Stanek 2009; Stanek et al.2012; Ogrinc et al.2016). The promising cytokine CXCL13 appears not to be a specific marker for active Lyme borreliosis (Ljøstad and Mygland 2008; Schmidt et al.2011; Wutte et al.2011a,b; Cerar et al.2013). Nevertheless, the greater inflammatory potential of B. burgdorferi over B. afzelii and B. garinii has been demonstrated in vitro and in vivo (Strle et al.2009). Despite the marked impression of a typical EM, its histological picture is generally non-specific. Even in ACA and borrelial lymphocytoma, the histological picture, although supportive, is not sufficiently specific for unequivocal evidence. The characteristic CSF lymphocytic pleocytosis may be absent very early in the involvement of the CNS, particularly in children (Millner et al.1989) and in some patients with peripheral facial palsy. Common and supportive findings in patients with CNS involvement are intrathecal IgM and IgG production and oligoclonal IgG bands which are detectable for a few weeks or longer. The concentration of glucose in CSF is usually normal. Patients with ACA and longstanding peripheral polyneuropathy have—as a rule—normal CSF findings. Direct detection of the agent Culture.Borrelia burgdorferi s.l. strains can be grown in complex media (Barbour 1984; Preac-Mursic et al.1996). The success of cultivation depends on the clinical presentation and the type of specimen. For example, cultivation of B. burgdorferi s.l. from skin biopsies of EM is usually very successful, at 50%–80% (Ružić-Sabljić et al.2000,2002; Aguero-Rosenfeld et al.2005; Cerar et al.2010; Stupica et al.2012,2015; O’Rourke et al.2013; Strle et al.2013a). However, EM will usually be identified by inspection, and cultivation is only rarely requested. In CSF, the success of culture is usually around 10% to 15% or less, possibly increasing to 30% in children in the very early phase of neurological disorders (Millner et al.1989; Strle et al.2006; Ogrinc et al.2013, 2016). Borrelia burgdorferi s.l. strains have been isolated from the blood of patients with EM, most successfully in the USA, by using high-volume blood cultures (Wormser et al.2005), and also from cardiac tissue of patients with dilated cardiomyopathy (Stanek et al.1990) and synovial fluid of patients with Lyme arthritis (Marlovits et al.2004). However, the relatively sophisticated demands of B. burgdorferi s.l. culture would not be managed in most medical laboratories. Nucleic acid amplification techniques PCR methods are available for the detection of low copy numbers of the genus Borrelia and the genospecies of Lyme borreliae. Unlike culture, conventional PCR cannot explicitly establish whether or not an infection is active since PCR detects borrelial DNA of both viable and non-viable organisms. Whether PCR is a valuable tool particularly in the diagnosis of arthritis in Europe remains to be substantiated. In a study from North America, borrelial DNA could be detected in about 85% of synovial fluid samples and even more if the synovial membrane is examined (Nocton et al.1994). Urine has been investigated by several groups (Pleyer et al.2001; Aberer et al.2007); however, results are contradictory (Rauter et al.2005). Thus, PCR results should always be interpreted with caution and the clinical significance of a PCR-positive finding in urine remains to be established. It should be emphasised that a negative result for culture and/or PCR does not exclude active infection because both methods are dependent on sample success. Indirect detection of a Borrelia burgdorferi s.l. infection: serology The previously mentioned problems with direct detection procedures paved the way for the success of serological tests. Serum specimens are easily obtained and processed. Today, an uncountable number of commercial products are available for detection of IgG and IgM antibodies against B. burgdorferi s.l. Test systems now comprise numerous techniques including immunofluorescence, enzyme-linked immunosorbent assay (ELISA), chemiluminescence, luminex and immunoblot among others. ELISA is still the most frequently used test system. However, interest in more flexible multiplex detecting systems is increasing. Serodiagnosis of Lyme borreliosis is currently based on the two-tier testing procedure, meaning that positive and borderline results in a sensitive screening assay are tested for specificity in an immunoblot system. Most screening assays are either enriched with VlsE (variable-like sequence expressed) antigen or use VlsE or C6 as a single antigen for detection of specific IgG antibodies. OspC is used for detection of specific IgM antibodies, either as a single antigen or in a mixture with other antigens. VlsE and C6 were originally considered markers for active infection but the strong immune reaction to these antigens is also present in convalescent and healthy persons, and thus does not differentiate between active and past infection. Immunoblot (western blot) can characterise the immune responses to specific proteins of B. burgdorferi s.l. The interpretation criteria for immunoblot results are based on diagnostic antigens of which most were identified in the late 1990s (Hauser, Lehnert and Wilske 1999; Wilske et al.1999, 2000). Line blots using recombinant antigens are currently replacing immunoblots. The European Union Concerted Action on Lyme Borreliosis/EUCALB has conducted a multicentre study in order to elaborate standardisation of criteria for interpretation of immunoblot results in Europe. Although a set of eight bands were identified as significant in each participant laboratory, no single rule could be formulated for use across Europe (Robertson et al.2000). Recombinant immunoblots were expected to solve this problem (Wilske et al.1999). However, in terms of sensitivity and specificity, recombinant IgM blots in particular not infrequently produce false-positive results (Seriburi et al.2012; Wormser et al.2013). In another study, the diagnostic accuracy of a single-tier commercial C6 ELISA kit was compared with two-tier testing. The results showed that the C6 ELISA as a single-step serodiagnostic test provided increased sensitivity in early Lyme borreliosis with comparable sensitivity in later manifestations of Lyme borreliosis (Wormser et al.2013). The shortcomings of two-tier serological testing in Lyme borreliosis are thus obvious and include low sensitivity in early disease, increased cost, time and labour, and subjectivity in the interpretation of immunoblots (Wormser et al.2013). The results of several studies suggest that the ELISA systems that use Vlse and OspC as antigens for detecting Borrelia-specific IgG and IgM antibodies show sufficiently sensitivity and specificity to replace the two-tier test principle (Steere et al.2008; Branda et al.2011,2013; Wormser et al.2013,2014; Moore et al.2016). However, even if the two-tier principle is modified or abandoned, there is still no method or technique for identification of active infection. Assays such as the lymphocyte transformation test are recommended for the identification of active Lyme borreliosis even in seronegative cases. Critical evaluation, however, shows that this is not the fact (Dessau et al.2014). A substantial difficulty is the relatively high prevalence of antibodies to B. burgdorferi s.l. in the general population, which is not directly related to the prevalence of disease. Persons such as hunters continuously exposed to ticks show an age-related seroprevalence (Cetin et al.2006). After more than 20 years of ‘Lyme serology’, it often appears that for diagnostic purposes serology has created nearly as many problems as it has solved. The immune response to borrelial infection still requires further elucidation. However, demonstration of borrelial IgG antibodies remains an indisputable approach to support diagnosis of long-lasting clinically well-defined manifestations of Lyme borreliosis. Furthermore, serology for detection of intrathecal production of specific antibodies—expressed as the CSF/serum index or antibody index (AI)—is very beneficial in the diagnosis of LNB (Wilske et al.1986; Cerar et al.2010; van Burgel et al.2011; Djukic et al.2012; Stanek et al.2014; Ogrinc et al. 2015, 2016). The IgG-AI expresses the proportion of IgG antibodies against of B. burgdorferi s.l. in the total IgG content in the CSF compared with the serum. An index above 1.0 would, strictly mathematically, prove the intrathecal production of specific antibodies. With respect to small volume variations when diluting samples, an index of >1.4 is considered significantly elevated (Reiber and Peter 2001). Table 1 refers to recommendations listing the suspected clinical conditions and the weight of laboratory results required to confirm the clinical suspicion (Stanek et al.2011). Table 1. Laboratory support in the diagnosis of Lyme borreliosis; modified according to the clinical case definitions in Lyme borreliosis (Stanek et al.1996, 2011). Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy a Specific antibody levels in serum may increase in response to progression of infection or treatment, or may decrease due to abrogation of the infection process. Samples collected a minimum of 3 months apart may be required in order to detect a decrease in IgG levels. b Intrathecally produced specific antibodies are determined by investigating simultaneously drawn samples of CSF and serum. View Large Table 1. Laboratory support in the diagnosis of Lyme borreliosis; modified according to the clinical case definitions in Lyme borreliosis (Stanek et al.1996, 2011). Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy a Specific antibody levels in serum may increase in response to progression of infection or treatment, or may decrease due to abrogation of the infection process. Samples collected a minimum of 3 months apart may be required in order to detect a decrease in IgG levels. b Intrathecally produced specific antibodies are determined by investigating simultaneously drawn samples of CSF and serum. View Large Treatment and prevention Treatment It should again be noted that early manifestations of Lyme borreliosis, both localised and disseminated, eventually heal spontaneously without antibiotic treatment. The main reason to treat such patients is to shorten the duration of the manifestation and to prevent the development of later complications, especially LNB and Lyme arthritis; the latter occurred in more than 80% of untreated patients in the USA (Kalish et al.2001). In Europe, the chronic skin manifestation ACA may develop with all its complications (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Strle and Stanek 2009). Results of in vitro studies have shown that B. burgdorferi s.l. strains are susceptible to most penicillins, many second-generation and third-generation cephalosporins, tetracyclines and macrolides; they are resistant to specific fluoroquinolones, rifampicin and first-generation cephalosporins (Baradaran-Dilmaghani and Stanek 1996; Preac-Mursic et al.1996; Hunfeld et al.2005; Wormser et al.2006; Morgenstern et al.2009; Veinović et al.2013). Doxycycline, amoxicillin, phenoxymethylpenicillin and cefuroxime axetil are highly effective and are the preferred antimicrobial agents for the treatment of early localised manifestations. Macrolides such as azithromycin seem to be clinically somewhat less effective than other oral antibiotics and are consequently used as second-line treatment (Wormser et al.2006; Stanek et al.2012). Early disseminated disease such as LNB is usually treated with intravenous ceftriaxone or penicillin. However, results of more recent studies suggest that oral doxycycline treatment of LNB is as effective as intravenous ceftriaxone for the treatment of European adults with LNB (Borg et al.2005; Ljøstad et al.2008). The shortest duration of effective treatment has never been assessed for any of the antimicrobial agents listed above. Today, it is recommended that antibiotics should be administered for 2 weeks in cases of early localised and early disseminated disease. For chronic manifestations, a 4-week course is recommended. However, in early treatment studies patients suffering from Garin-Bujadoux-Bannwarth meningopolyneuritis were treated with intravenous penicillin G, 2 × 10 million units per day for 10 days, and in another study a similar cohort of patients was treated with intravenous ceftriaxone, 2 g per day, again for 10 days (Kristoferitsch et al.1987,1989). The outcome of treatment was compared with a cohort of well-documented Garin-Bujadoux-Bannwarth meningopolyneuritis patients who were not treated with antibiotics or with corticosteroids because they were seen before the spirochaetal aetiology of these disorders was discovered. Comparison of both groups revealed a significant improvement in patients whose treatment was started within 5 weeks after onset of the neurological disease (Kristoferitsch et al.1987,1989). That only 10 days of treatment is effective in early disease has been shown for doxycycline in a prospective (Wormser et al.2003) and a large retrospective clinical trial in the USA (Kowalski et al.2010). In a European study, the efficacies of 10 days and 15 days of oral doxycycline therapy were evaluated in adult patients with EM. A complete response was observed in 93% of the 15-day group and in 92% in the 10-day group. The frequency of non-specific symptoms in the patients was similar to that among controls. Thus, it was concluded that the 10-day regimen of oral doxycycline was not inferior to the 15-day regimen among adult European patients with solitary EM (Stupica et al.2012). Lyme arthritis typically responds to antibiotic treatment. Patients whose arthritis is improved but not resolved after an initial course of oral treatment can be re-treated with a second course of oral antibiotics, reserving parenteral antibiotic treatment for those without any substantial clinical response (Wormser et al.2006). Intra-articular steroids are not recommended before or during antibiotic treatment based on retrospective studies suggesting the potential for worse outcomes. Non-steroidal anti-inflammatory agents (NSAIDs) may be given with antibiotic therapy, and—since persistence of mild joint inflammation immediately following antibiotic therapy is found in about 25% of patients with Lyme arthritis—may also be required in several patients after antibiotic treatment. After resolution of arthritis of the knee, physical therapy may be needed if quadriceps atrophy has developed (Steere et al.2016). In patients not responding to NSAIDs, methotrexate or similar disease-modyfying antirheumatic drugs, given for 6–12 months, are usually effective. In patients with incomplete responses, arthroscopic synovectomy is an option (Avikar and Steere 2015; Steere et al.2016). Recommended antibiotic treatment for patients with Lyme borreliosis is shown in Table 2. Table 2. Recommended antibiotic treatment for patients with Lyme borreliosis; modified after Stanek et al. (2012). Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy od = once daily; bid = two times daily; tid = three times daily; qid = four times daily. i.v. = intravenous; IE = international units; a For children, total daily dosage is given, divided into the number of doses per day. b Age <8 years. c Azithromycin and erithromycin are used in patients allergic to penicillin and tetracyclines. d Ceftriaxone and penicillin G are used for treatment of erythema migrans and borrelial lymphocytoma very rarely (potentially for patients with severe immunodeficiency and for pregnant women). e Early Lyme neuroborreliosis is as a rule treated for 2 weeks, heart involvement for 2–3 weeks, late Lyme neuroborreliosis for 4 weeks. f For treatment of early Lyme neuroborreliosis, more information is available for 200 mg once daily than for 100 mg twice daily. g In case of recurrent Lyme arthritis or partial response to the initial treatment. h Ceftriaxone is most often used when there had been only a minimal response to previous oral antibiotics. View Large Table 2. Recommended antibiotic treatment for patients with Lyme borreliosis; modified after Stanek et al. (2012). Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy od = once daily; bid = two times daily; tid = three times daily; qid = four times daily. i.v. = intravenous; IE = international units; a For children, total daily dosage is given, divided into the number of doses per day. b Age <8 years. c Azithromycin and erithromycin are used in patients allergic to penicillin and tetracyclines. d Ceftriaxone and penicillin G are used for treatment of erythema migrans and borrelial lymphocytoma very rarely (potentially for patients with severe immunodeficiency and for pregnant women). e Early Lyme neuroborreliosis is as a rule treated for 2 weeks, heart involvement for 2–3 weeks, late Lyme neuroborreliosis for 4 weeks. f For treatment of early Lyme neuroborreliosis, more information is available for 200 mg once daily than for 100 mg twice daily. g In case of recurrent Lyme arthritis or partial response to the initial treatment. h Ceftriaxone is most often used when there had been only a minimal response to previous oral antibiotics. View Large Pregnant women with Lyme borreliosis receive the same antibiotic treatment as women who are not pregnant, except that doxycycline should be avoided. A congenital Lyme borreliosis syndrome is not reliably supported by any study (Maraspin et al.1996; Wormser et al.2006; Lakos and Solymosi 2010). According to rather limited data, the antibiotic treatment approach used for immunocompetent patients with EM is also effective in immunocompromised patients (Maraspin et al.1999b, Fürst et al.2006; Maraspin, Ruzic-Sabljic and Strle 2006), including those with underlying haematological malignancy (Maraspin et al.2015). Most probably the same is also valid for disseminated Lyme borreliosis such as LNB: immunocompromised patients (including those receiving biological therapy) can be effectively treated using the same antibiotics in equivalent dosages and duration as used for treatment of immunocompetent patients (Merkac, Tomazic and Strle 2015). Prevention The best way to avoid Lyme borreliosis is to avoid tick-infested areas, though this is not a realistic recommendation. A more practical measure is to wear protective clothing and/or use tick repellents on clothing and skin, particularly for those persons whose profession or passion requires periods in tick-infested areas. After exposure, inspection of the entire skin surface to remove any attached ticks is recommended because of the delay between the time of tick attachment and transmission of B. burgdorferi s.l. (see Fig. 3). Inspection of the scalp should be included and is particularly needed in small children who experience tick-bites on the scalp most frequently (Berglund et al.1995). A traditional recommendation is to remove the attached tick from the skin by grasping it with tweezers as close to the mouthparts as possible and then gently pulling it out. This recommendation, however, appears to be of little value when it comes to the tiny larvae or also I. scapularis nymphs that are smaller than Ixodes ricinus nymphs, and to parts of the body where it is difficult to make use of tweezers. Chemoprophylaxis with a single dose of 200 mg doxycycline after removal of an I. scapularis or an I. pacificus tick within 72 h was found beneficial in the USA (Nadelman et al.2001; Warshafsky et al.2010). In Europe, the principle of ‘watch and wait’ is recommended for I. ricinus tick bites because studies on the efficacy of antibiotic prophylaxis are limited (Schwameis et al.2017) and because overuse of antibiotics should be avoided. Further, the efficacy of antibiotic treatment of early localised and disseminated manifestations of Lyme borreliosis has been established (Stanek and Kahl 1999; Stanek et al.2012). Modification of the environment may reduce the density of tick populations around residences; for example, by the removal of leaf litter, the placing of wood chips where lawns are adjacent to forests, application of acaricides and the construction of fences to keep out deer (Stafford and Kitron 2002). According to American data, approaches to eradicate ticks and/or reservoir hosts have limited efficacy (Clark and Hu 2008); there are very few similar European information. Currently, no vaccine is available for prevention of Lyme borreliosis in humans; however, attempts to develop a vaccine continue (Barrett and Portsmouth 2013; Wressnigg et al.2013). Nevertheless, patients with Lyme borreliosis who are treated with appropriate antibiotics have an excellent prognosis. European Lyme borreliosis is a frequent disease with an increasing incidence in many countries. 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Lyme borreliosis–from tick bite to diagnosis and treatment

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Blackwell
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© FEMS 2018.
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0168-6445
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1574-6976
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Abstract

Abstract Lyme borreliosis is caused by certain genospecies of the Borrelia burgdorferi sensu lato complex, which are transmitted by hard ticks of the genus Ixodes. The most common clinical manifestation is erythema migrans, an expanding skin redness that usually develops at the site of a tick bite and eventually resolves even without antibiotic treatment. The infecting pathogens can spread to other tissues and organs, resulting in manifestations that can involve the nervous system, joints, heart and skin. Fatal outcome is extremely rare and is due to severe heart involvement; fetal involvement is not reliably ascertained. Laboratory support—mainly by serology—is essential for diagnosis, except in the case of typical erythema migrans. Treatment is usually with antibiotics for 2 to 4 weeks; most patients recover uneventfully. There is no convincing evidence for antibiotic treatment longer than 4 weeks and there is no reliable evidence for survival of borreliae in adequately treated patients. European Lyme borreliosis is a frequent disease with increasing incidence. However, numerous scientifically questionable ideas on its clinical presentation, diagnosis and treatment may confuse physicians and lay people. Since diagnosis of Lyme borreliosis should be based on appropriate clinical signs, solid knowledge of clinical manifestations is essential. Lyme borreliosis, clinical manifestations, diagnosis, treatment, Borrelia burgdorferi sensu lato, erythema migrans INTRODUCTION Lyme borreliosis is considered the most frequent tick-borne disease in the moderate climates of the northern hemisphere. The infection is caused by specific genospecies of Borrelia burgdorferi sensu lato (s.l.). Lyme borreliosis is a disease with diverse clinical presentations. Signs and symptoms allow proper diagnosis of the disease. It is obvious that there can be no diagnosis of Lyme borreliosis in the absence of clinical manifestations. Thus, the most important step in diagnosing Lyme borreliosis is that physicians acquire a good knowledge of the clinical features through clinical instruction and personal experience. Nevertheless, it is most supportive and enlightening to consult the available case definitions, guidelines, reviews and seminar articles in peer-reviewed publications in order to learn about evidence-based knowledge of Lyme borreliosis (Wormser et al.2006; Strle and Stanek 2009; Mygland et al.2010; Stanek et al.2011, 2012; Shancez et al.2016; Steere et al.2016). Caution should be exercised when consulting the web for comprehensive information on the disease complex as there are hundreds of sites available (Sood 2002) with a lot of misinformation. The most frequently affected organ in Lyme borreliosis is the skin, followed by the nervous system and joints. Certain spirochaetes of the B. burgdorferi s.l. complex are the causative agents of the disease. These Borrelia species occur in natural foci in vertebrate reservoir hosts, and in certain Ixodes tick species that are responsible for transmission to other vertebrates, including man. As a tick-borne disease, Lyme borreliosis shows relatively constant seasonal peaks of the skin manifestation erythema migrans (EM) following the seasonal activity of ticks, whereas disseminated or late disease may appear throughout the year. Uncritical interpretation of symptoms may sometimes lead to incorrect interpretation of laboratory test results. Not infrequently a positive serological result in an otherwise healthy person may lead to the misinterpretation of active Lyme borreliosis and be followed by unnecessary antibiotic treatment. On the contrary, some patients with typical signs remain undiagnosed and untreated. Physicians should also be aware that Lyme borreliosis in North America and in Europe differ in their clinical presentations in some respects (Strle et al.1999, 2011; Cerar et al.2016). A reliable clinical diagnosis of Lyme borreliosis is only possible in a case of typical EM. Other manifestations of Lyme borreliosis such as borrelial lymphocytoma on the ear lobe, meningoradiculoneuritis (Garin-Bujadoux-Bannwarth syndrome) and acrodermatitis chronica atrophicans (ACA) are also highly supportive of the diagnosis. However, with the exception of typical EM, laboratory confirmation is needed in any case that is clinically suspicious for Lyme borreliosis. It should also be emphasised that the traditional early dividing of Lyme borreliosis into numbered stages—following the syphilis model—is only partly in agreement with clinical findings. A more flexible descriptive terminology is recommended, namely early localised, early disseminated or late disease. The aim of this review article is to provide detailed information on the various clinical presentations of Lyme borreliosis with respect to diagnosis and treatment. The emphasis in this review is on European Lyme borreliosis; information on the disease in North America has been included for illustrative purposes. Lyme borreliosis or Lyme disease? Lyme borreliosis refers to a disease caused by particular infectious organisms of the B. burgdorferi s.l. complex. The earlier name of Lyme disease described a disease without a known cause and as sometimes used currently does not necessarily mean that an infectious organism is present. Namely, the term Lyme disease is now frequently but misleadingly applied to a broad spectrum of symptoms in cases of long-term illness where the infectious agent is unknown and not demonstrable, often referred to as ‘chronic Lyme disease’. It would therefore be desirable to emphasise Lyme borreliosis as the specific term. A look back into the history of Lyme disease shows that Lyme arthritis and Lyme carditis were first observed in the communities of Lyme, Old Lyme and East Haddam in Connecticut, USA (Steere et al.1977b) and Lyme disease was adopted for an enlarging spectrum of symptoms that were obviously linked to each other by an aetiology that remained unknown until the early 1980s (Steere et al.1977a). After the discovery of Borrelia in Ixodes scapularis ticks from Long Island, NY (Burgdorfer et al.1982; Barbour et al.1983), and their aetiologic role in these disorders (Benach et al.1983; Steere et al.1983b; Barbour 1984), the more specific term Lyme borreliosis was introduced (Stanek et al.1987a). This term also comprises the clinical manifestations erythema chronicum migrans, lymphadenosis benigna cutis/borrelial lymphocytoma, ACA and meningopolyneuritis that were known in Europe (Herxheimer and Hartmann 1902; Afzelius 1910; Lipschütz 1913; Bäverstedt 1943; Hörstrup and Ackermann 1973) decades before recognition of Lyme arthritis and are now linked together in a nosological entity. Although ‘Lyme’, the name of the small communities, appears to be irrelevant in describing the disease, the terms Lyme borreliosis and Lyme disease have been used extensively and will thus now remain to describe a disorder that exists in moderate climates throughout the northern hemisphere (Stanek et al.2012). Borrelia burgdorferi sensu lato—the pathogens Detailed information on the biology of B. burgdorferi s.l. and its infectious cycle is given in a review by Mannelli et al. (2012). Briefly, Borrelia are spirochaetal bacteria consisting of a protoplasmic cylinder surrounded by 7 to 12 endoflagellae inserted in both ends of the elongated (10–30 μm length) but slender (0.2–0.5 μm diameter) organisms and overlapping in the middle. The entire structure is enclosed by a flexible outer membrane (Barbour 1988) that does not contain lipopolysaccharide but is instead equipped with outer surface lipoproteins (Osps). Moreover, these borreliae harbour a linear chromosome—an almost unique feature in the bacterial domain (Barbour and Hayes 1986)—and several linear and circular plasmids in which relevant Osps are encoded. Among the currently described genospecies of B. burgdorferi s.l. (Stanek and Reiter 2011; Mannelli et al.2012), the prevailing pathogens of Lyme borreliosis in Europe are the genospecies B. afzelii, B. garinii, B. bavariensis (formerly B. garinii OspA type 4) and B. burgdorferi (B. burgdorferi sensu stricto). B. spielmanii, B. bissetii, B. valaisiana and B. lusitaniae have been identified as pathogens in single cases only (Picken et al.1996; Maraspin, Ruzic-Sabljic and Strle 2006; Fingerle et al.2008; Stanek and Reiter 2011; Stanek et al.2012; Stupica et al.2015). The predominant agent of Lyme borreliosis in North America is B. burgdorferi. In single cases, B. bissetti, B. americana and B. andersonii were found in human blood (Girard, Fedorova and Lane 2011; Clark, Leydet and Hartman 2013). Recently, B. mayonii was described as a novel genospecies and human pathogen in the B. burgdorferi sensu lato complex (Pritt et al.2016). Figure 1 illustrates the relative frequency of different B. burgdorferi s.l. genospecies isolated from the skin lesions of patients in Slovenia with EM (Strle et al.1996c; Ružić-Sabljić et al.2000; Stupica et al.2015), and Fig. 2 shows the relative frequency of different genospecies isolated from cerebrospinal fluid (CSF) (Ružić-Sabljić et al.2001; Strle et al.2006; Ogrinc et al.2013, 2016). Information on relative frequency of genospecies found in individual clinical manifestations of Lyme borreliosis is based on findings from only a few European countries, they may not be representative for a larger (European) geographic area. Figure 1. View largeDownload slide Distribution of genospecies (%) among 488 skin isolates of B. burgdorferi s.l. from Slovenian patients with erythema migrans (Ružić-Sabljić et al.2002). Figure 1. View largeDownload slide Distribution of genospecies (%) among 488 skin isolates of B. burgdorferi s.l. from Slovenian patients with erythema migrans (Ružić-Sabljić et al.2002). Figure 2. View largeDownload slide Distribution of genospecies (%) of B. burgdorferi s.l. among 120 CSF isolates from European patients with Lyme neuroborreliosis (Strle et al.2006). Figure 2. View largeDownload slide Distribution of genospecies (%) of B. burgdorferi s.l. among 120 CSF isolates from European patients with Lyme neuroborreliosis (Strle et al.2006). Tick bite and transmission of pathogens The vectors of B. burgdorferi s.l. are hard ticks of the genus Ixodes. The active developmental stages of larva, nymph and adult female each take a single blood meal. The adult male tick may take sporadic small meals. Borrelia burgdorferi s.l. is taken up with the blood when the tick, usually a larva or a nymph, feeds on an infected reservoir host. The spirochaete locates in the midgut of the tick and is transmitted by the next tick stage when it feeds on another vertebrate host, which can include man. The adult female is usually a dead end for B. burgdorferi s.l. because transovarial transmission is rare (Mannelli et al.2012; Rollend, Fish and Childs 2013; EUCALB 2010). The blood meal is a stimulus for B. burgdorferi s.l. to detach from the epithelium of the midgut of the tick, enter the haemolymph and migrate to the salivary glands. Blood meal results in an upregulation of surface proteins such as OspC, DbpA, DbpB and P66, and downregulation of OspA and OspB. The borreliae are then transmitted to the host with the saliva. Factors contained in tick saliva enhance the survival of the bacteria by attenuating the local immune response at the site of the tick bite, and co-feeding apparently increases the frequency of OspC variants (Rosa 2005; Pérez et al.2011). Strategies to overcome complement attacks play an important part in the immune evasion of borreliae (Kraiczy et al.2000; Kraiczy 2016). Borrelia bind to a variety of host tissue components such as plasmin and factor H, which may facilitate the tissue invasion process (Kraiczy and Stevenson 2013). One of the frequently asked questions is: What is the minimum feeding period required for an infected tick to transmit borreliae that eventually cause disease in humans? An answer was obtained from records of patients with EM in Austria and Slovenia. The records were evaluated independently and gave almost identical results (Strle et al.1996a; Stanek and Kahl 1999). Most of the patients had discovered the attached tick on the day after the putative tick attachment. In both countries, the feeding period of the ticks before detection and removal was more than 12 h in the majority of patients and in about a third it was more than 24 h. However, 14%–18% of exposed persons removed the tick within 6 h and subsequently developed EM (Fig. 3). The relatively early transmission in Europe compared with the USA is supported by findings in laboratory experiments on transmission (Kahl et. al. 1998). Figure 3. View largeDownload slide Reports from patients on the estimated duration (hours) of tick attachment before removal from the skin and subsequent erythema migrans. Results (%) from studies in Austria (AT, n = 254) and Slovenia (SI, n = 212). Figure 3. View largeDownload slide Reports from patients on the estimated duration (hours) of tick attachment before removal from the skin and subsequent erythema migrans. Results (%) from studies in Austria (AT, n = 254) and Slovenia (SI, n = 212). Asymptomatic infections In the USA, B. burgdorferi may cause asymptomatic infection in about 10% of patients (Steere et al.2003), while in a study of seroprevalence in Sweden, more than half of seropositive subjects did not remember having symptoms of Lyme borreliosis (Wilhelmsson et al.2016). These data suggest that in North America borrelial infections appear to lead to disease more frequently. Lyme borreliosis—the disease Lyme borreliosis can involve several organ systems and may have different clinical presentations. Information on the relative frequency of individual clinical manifestations of the disease in Europe is very limited. Skin is the most frequently involved tissue in Lyme borreliosis, and usually clinically the most characteristic, and thus provides clues for the diagnosis (Strle and Stanek 2009). The findings from Slovenia, which are not necessarily representative for whole Europe, are shown in Fig. 4. Figure 4. View largeDownload slide Frequency (%) of main clinical manifestations of Lyme borreliosis in adults (n = 745) and children (n = 275). Data of the year 2000 from the Department of Infectious Diseases at the University Medical Centre, Ljubljana, Slovenia. Figure 4. View largeDownload slide Frequency (%) of main clinical manifestations of Lyme borreliosis in adults (n = 745) and children (n = 275). Data of the year 2000 from the Department of Infectious Diseases at the University Medical Centre, Ljubljana, Slovenia. In the USA, EM is the presenting manifestation in approximately 80% of patients with Lyme borreliosis; in about 15% of patients, non-specific symptoms occur during summer without the skin lesion, and in the remaining 5%, the disease presents with a later manifestation of the illness, such as Lyme neuroborreliosis (LNB) or arthritis (Steere and Sikand 2003). Hereafter we present the main clinical characteristics of Lyme borreliosis, including some illustrative cases of different manifestations of the disease. All the patients presented as cases originated from, or were exposed to ticks in, Lyme borreliosis endemic regions. Skin manifestations EM, borrelial lymphocytoma (formerly lymphadenosis benigna cutis) and ACA are characteristic manifestations of Lyme borreliosis. Other skin manifestations such as scleroderma circumscripta, lichen sclerosus et atrophicus and cutaneous B-cell lymphoma may also be associated with Lyme borreliosis. Erythema migrans EM is defined as an erythematous skin lesion that develops days to weeks later at the site where borreliae were transferred into the skin by the bite of an infected tick (Fig. 5). The lesion typically begins as a red macula or papule and expands over days to weeks with or without central clearing. For a reliable diagnosis, a single primary lesion must reach ≥5 cm in diameter. A lesion <5 cm qualifies for the diagnosis of EM only if it develops at the site of a tick bite, if its onset has a free time interval of at least 2 days and if the lesion is enlarging (Stanek et al.2012). Multiple EM is defined as the presence of two or more skin lesions, one of which must fulfil the size criteria for solitary EM. Figure 5. View largeDownload slide Erythema migrans (EM) lesions: (a) EM shoulder, (b) EM knee pit, (c) EM lower leg, a day after onset of treatment, (d–f) EM ∼9 weeks after onset; tick bite in the axilla, (g) EM started at the breast 6 months before (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 5. View largeDownload slide Erythema migrans (EM) lesions: (a) EM shoulder, (b) EM knee pit, (c) EM lower leg, a day after onset of treatment, (d–f) EM ∼9 weeks after onset; tick bite in the axilla, (g) EM started at the breast 6 months before (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). EM, the most frequent manifestation of Lyme borreliosis, may represent about 90% of registered cases in countries of central Europe (Anonymus 2015). According to Borrelia skin culture results, EM in western, central and eastern Europe is caused predominantly by B. afzelii (70%–90%), less frequently by B. garinii (10%–20%), rarely by B. burgdorferi and only exceptionally by other species such as B. bissettii, B. spielmanii and as yet unidentifiable species. However, B. garinii dominates in north-eastern Europe (Oksi et al.2001; Stanek et al.2012). Between 58% and 73% of European patients with EM recall a previous tick bite at the site of the EM (Strle et al.2002) but only one in four patients with EM in the USA (Strle et al.1999; Wormser et al.2006). Histological examination of the dermis reveals mild superficial perivascular infiltration by lymphocytes and some histiocytes, sometimes accompanied by plasma cells and rarely by neutrophils (Stanek and Flamm 1991; de Koning and Duray 1993). The epidermis is usually not affected. The infiltration predominantly consists of macrophages and CD8+ and CD4+ T cells along with smaller numbers of B cells and plasma cells. Involvement of cell-mediated immune mechanisms in the initial host response to Lyme borreliae is indicated by the presence of T cells and increased numbers of Langerhans cells. High levels of the T-cell-active chemokines CXCL9 and CXCL10 and low levels of the B-cell-active chemokine CXCL13 have been demonstrated. CD3(+) T cells and CXCL9 have been shown by immunohistological methods (Müllegger et al.2007). The seasonal occurrence of EM is pronounced because the onset of the lesion usually occurs soon after the tick bite. Untreated EM may persist and expand over weeks to several months, their diameter ranging from a few centimetres to more than a metre (Fig. 5). In adult patients, EM is most often located on the lower extremities; in children, the upper part of the body is relatively more often involved (Berglund et al.1995; Strle 1999a; Logar et al.2004; Strle et al.2011). The location of EM is in accordance with data about location of tick bites (Robertson, Gray and Stewart 2000). Mild local symptoms such as mild itching, burning or pain at the site of EM may be recalled in about half of European patients with EM. A smaller proportion of patients (about one third) may experience systemic symptoms, such as fatigue and malaise, headache, myalgia and arthralgia, which are usually intermittent and often vary in intensity and location. Fever is an exception in adult European patients, whereas it is present more frequently in patients in the USA (Strle et al.1996c, 1999; Dandache and Nadelman 2008; Cerar et al. 2010; Ogrinc et al.2013). Further, EM in the USA has a greater frequency of abnormal findings including lymphadenopathy (39% vs 9%) and fever (15% vs 1%), and differences in the humoral immune response (Strle et al.1999). In multiple EM, the secondary lesions are similar in morphology to the initial solitary lesion but lack the indurated centre usually seen in primary lesions at the site of the tick bite; secondary lesions are also smaller and are only exceptionally associated with local itching or pain. They appear to be more frequent in children than in adults, and are apparently a more common finding in EM in the USA (Strle et al.1996a, b; Strle and Stanek 2009). Differential diagnoses comprise tick-bite or insect-bite hypersensitivity reaction, fungal infection such as tinea corporis (ring worm), erysipelas, urticaria, contact eczema, folliculitis, cellulitis, granuloma annulare and fixed drug eruption (Strle and Stanek 2009; Stanek et al.2012). Case 1. A 45-year-old woman experienced a tick bite on her right thigh in late June. Two weeks later, a small redness appeared at the site of the bite. The redness was mildly itchy and slowly expanding. Seven days later it began to fade in the middle, became ring-like and continued to spread, so that in the middle of September the erythema expanded over the whole right leg. With the exception of mild itching the patient had no other symptoms. This was the reason that she did not seek for medical help for more than 2 months after the onset of the lesion. Her doctor did not order any laboratory tests but prescribed the patient doxycycline 100 mg bid for 14 days. The skin lesion began to fade at the end of the first week of treatment and disappeared completely at the end of therapy. No other manifestations of Lyme borreliosis appeared within 1 year after the end of antibiotic treatment. Comment: A typical course of EM, including proper management and favourable outcome of the early Lyme borreliosis manifestation. Case 2. A 31-year-old woman presented mid May with a small erythematous area in her umbilicus. She claimed that she rubbed the umbilicus because of itching and found something black on her finger which could have been a tick. The possible tick bite was on 15 May. Since the redness was not indicative of EM at that time point, she was asked by her doctor to observe the skin area and to come in again if the erythematous area enlarges. She accepted but wished to learn about her antibody status against Lyme borreliae and therefore a blood sample was drawn. However, the patient did not come in when she recognised enlargement of the erythema but several weeks later, on 21 June. At this time, a typical EM was present around her umbilicus with a diameter of 22 × 15 cm. Treatment with phenoxymethyl penicillin was prescribed 1000 000 IU tid for 14 days and a second blood sample was drawn. The erythema disappeared after the first week of treatment. Serology showed a seroconversion from negative results with the first blood sample to highly positive IgG and IgM results, in both ELISA and immunblot, with the second. Comment: The ‘wait and watch’ policy is recommended when an attached tick is removed or when a lesion is small and not identifiable as EM. If serology is perfomed, then two blood samples are needed: one is taken at the first visit and the other 3 to 6 weeks later. Seroconversion or a significant increase in the concentration of pre-existing antibodies may be observed. However, the diagnosis of a typical EM must be made on clinical basis! Borrelial lymphocytoma Case 3. A 9-year-old girl spent most of the summer time in forested landscape. From May to August, she had at least 10 tick bites. In early September, her parents noticed a small induration and oedema of her left earlobe. The swelling slowly grew in size. The skin was initially red, and later it gradually turned violet. The girl had no other complaints. Examination at the end of November revealed a bluish-red left earlobe, almost entirely swollen and somewhat more firm. Otherwise physical examination was normal. Basic laboratory blood tests revealed no abnormalities. IgM and IgG serum antibodies to B. burgdorferi s.l. were detected. The ear lobe lesion disappeared about 2 weeks after 14 days treatment with amoxicillin; later on the girl had no complaints. Comment: A typical course and outcome of borrelial lymphocytoma in a child. Case 4. A 56-year-old woman recognised an attached tick on the left side of her chest after having collected mushrooms in the forest. Ten days later she noticed a red patch on the skin at the site of the tick bite. The patch slowly expanded. After 1 week, it began to fade in the centre and became ring-like. The lesion expanded to diameter of about 30 × 20 cm, and lasted for about 7 weeks. Approximately 10 days before it disappeared, the patient noticed that the mammilla of her left breast was swollen; it was sensitive to touch, and occasionally mildly itchy. The patient recalled tiredness and pain in the muscles of the limbs, headaches, dizziness and feeling of occasional irregular heartbeat. She visited her doctor for the first time about 3 weeks after the ring-like erythema lesion has disappeared. In the following 2 months, she was examined by an internist, cardiologist, neurologist and psychiatrist but the cause of her problems was not found. Her difficulties were interpreted as neurovegetative dystonia in association with menopause. An oncologist that she visited more than 4 months after the onset of the disease did not confirm suspicion of malignant breast disease but directed the patient to the Lyme borreliosis outpatient clinic. The nipple of the left breast was swollen, mildly hardened and minimally painful to touch; in the region of areola mammae, a tumour with a diameter of 3 cm was found. Otherwise the physical status of the patient was normal. High levels of IgG serum antibodies to B. burgdorferi s.l. were detected. Basic laboratory blood test results were in the normal range. The patient was treated with doxycycline 100 mg bid for 14 days. Fatigue, pains and dizziness disappeared by the end of treatment, while the breast tumour vanished completely in the following 6 weeks. One year later, the patient was without complaints but remained seropositive. Comment: A characteristic course and outcome of borrelial lymphocytoma in an adult person; diagnostic difficulties are usually due to limited knowledge. Borrelial lymphocytoma presents as a solitary swelling up to a few centimetres in diameter, and consists of a dense lymphocytic infiltration of dermis and subcutaneous tissue as a result of borrelial infection (Asbrink and Hovmark 1988; Strle et al.1992; Maraspin et al.2016). The infiltration is polyclonal with a predominance of B-lymphocytes and may show germinal centres (Asbrink and Hovmark 1988; Stanek and Flamm 1991). The predominance of B cells is in contrast with the findings in EM and ACA skin lesions where T cells prevail. High levels of the B-cell-active chemokine CXCL13 are found in this skin manifestation in contrast to EM and ACA (Müllegger et al.2007). Borrelial lymphocytoma is a rare manifestation of European Lyme borreliosis. It is more frequently observed in children than in adults: data from epidemiological studies and case records show a frequency of 1.5%–7% in children and 0.5%–2% in adults (Berglund et al.1995; Strle and Stanek 2009). In children, borrelial lymphocytoma is most frequently located on the ear lobe and in adults in the region of the areola mammae, rarely on the nose, arm, shoulder or scrotum (Strle et al.1996b). Borrelial lymphocytoma may appear after EM but sometimes together (Fig. 6) or even before EM. It also resolves eventually without treatment; however, sometimes it may take more than a year (Asbrink and Hovmark 1988; Strle et al.1992, 1996b). Other signs of Lyme borreliosis may develop in the course of untreated long-lasting borrelial lymphocytoma (Asbrink and Hovmark 1988; Strle et al.1992, 1996b). Accompanying systemic symptoms such as reported in case 3 are rare, but localised discomfort in the region of the areola mammae in cases of borrelial lymphocytoma of the breast appears to be a frequent finding. Antibodies to B. burgdorferi s.l. may be demonstrable in 50%–70% of patients at first visit. Basic blood tests usually show no abnormality (Strle et al.1992; Maraspin et al.2016). Figure 6. View largeDownload slide Borrelial lymphocytoma (BL): (a and b) BL on ear lobe, (c) BL on nipple surrounded by EM, (d) BL of nipple (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 6. View largeDownload slide Borrelial lymphocytoma (BL): (a and b) BL on ear lobe, (c) BL on nipple surrounded by EM, (d) BL of nipple (Pictures by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Borrelial isolates from borrelial lymphocytoma are rare (Strle et al.1996b; Maraspin et al.2002, 2016). The isolation rate is about 1/3 (Maraspin et al.2016). The isolates most frequently belong to the genospecies B. afzelii, in some cases to B. garinii and B. burgdorferi; B. bissettii has been detected in one patient (Picken et al.1997; Maraspin et al.2002, 2016; Ružić-Sabljić et al.2002). Differential diagnosis requires histological examination, particularly in patients with breast lymphocytoma or lymphocytoma at other (atypical) locations if an association with borrelial infection cannot be established (Strle et al.1996b) and B-cell lymphoma and pseudolymphoma are considered (Asbrink and Hovmark 1988; Strle et al.1992, 1996b; Maraspin et al.2002; Lipsker 2007). Acrodermatitis chronica atrophicans Case 5. A 55-year-old female reported that she has been bitten almost every year by a number of ticks since her childhood, but she did not remember an erythema at the site of the bites. Six and a half years previous to her visit, the back of her left hand became swollen and the skin bluish red. Although there were some mild transient improvements, the skin lesion slowly enlarged. In the following 2 years, similar skin lesions also appeared on the right hand and on right foot and the distal part of her right leg. The swellings slowly vanished and were replaced by a more and more thinning skin, which was vulnerable and of bluish colour. In the area of the gradually enlarging skin lesions, tingling sensations and severe burning pain began to appear, becoming more and more annoying. Several months later—more than 2 years after she noticed skin changes—pain with slowly increasing severity appeared in small joints of hands and feet. In the following years, the joints become deformed. Due to the deformity of the fingers on her right foot, she had increasing problems with the footwear. During this time, she had two episodes of a swollen right knee which lasted for more than 1 month. Physical examination revealed skin involvement of the distal parts of the limbs: distal to the midpoint of the left upper arm, distal to the right elbow and distal to the middle of the right lower leg. In the proximal parts of the involved skin, the changes were disseminated in the form of patches, while more distally skin was involved homogeneously. The skin was bluish, atrophic, in some parts—in particular on the back of her hands—it was wrinkled, translucent and with numerous prominent veins. A neurologist diagnosed the presence of polyneuropathy, X-ray examination disclosed subluxation of fingers of the right foot. Histologic examination of the skin revealed teleangiectasias, interstitial infiltration of the dermis and subcutaneous tissue with lymphocytes and plasma cells and thin hyperkeratotic epidermis. Serological testing revealed high levels of specific IgG serum antibodies. Comment: A course of ACA with the involvement of skin, peripheral nerves and joints. ACA is a chronic skin manifestation of Lyme borreliosis seen almost exclusively in Europe (Steere 1989; Stanek and Strle 2003; Wormser et al.2006). In contrast to EM and borrelial lymphocytoma, ACA does not disappear spontaneously (Asbrink and Hovmark 1988). The lesion is most often located on acral parts of the body, usually on the extensor part of hands or feet, and initially is usually unilateral, later on it may become more or less symmetrical. A previous other manifestation of Lyme borreliosis is usually not recalled by these patients. ACA is more often diagnosed in women than in men and occurs only very exceptionally in children. Patients are usually over 40 years old (Asbrink and Hovmark 1988; Strle et al.2013b, Ogrinc et al.2017). The disorder accounts for about 3% of cases of Lyme borreliosis (Berglund et al.1995) and is most frequently caused by B. afzelii but also by B. garinii and B. burgdorferi (Picken et al.1998; Ružić-Sabljić et al.2000, 2002). Because of the long incubation time and the long duration of the skin lesions prior to diagnosis, a history of tick bites is not supportive. Histological findings in the early lesions are non-specific perivascular lymphocytic infiltrates; the epidermis is frequently thinned. Band-like and perivascular infiltrates consisting of lymphocytes and plasma cells are seen in the upper and middle portions of the dermis, often combined with oedema (de Koning and Duray 1993). Dilated blood vessels can be found in the superficial dermis. Peri-articular fibroid nodules may be present in the deeper portions of the dermis extending into the subcutaneous fat. The nodules consist of a homogeneous eosinophilic centre surrounded by irregular fascicles of collagen, onion-like. Perivascular infiltrates of lymphocytes and plasma cells are present predominantly in the peripheral parts of the lesion, and fibrosis is pronounced. In the late stage of ACA, cutaneous atrophy is present with more or less pronounced inflammation (Fig. 7). In very long-standing atrophic lesions, the inflammatory infiltrates are sparse or may even be absent; collagen and elastic fibres are strongly reduced and degenerated. In general, histologically constant findings in active ACA lesions are telangiectases and a lymphocytic infiltrate with a moderate-to-rich admixture of plasma cells (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986). However, the histopathological pattern is not diagnostic in itself (Brehmer-Andersson, Hovmark and Asbrink 1998). Figure 7. View largeDownload slide Acrodermatitis chronica atrophicans; atrophic skin (Picture by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Figure 7. View largeDownload slide Acrodermatitis chronica atrophicans; atrophic skin (Picture by Cortesy of Hasel Druck und Verlag GmbH, 1090 Vienna, Austria). Clinically, the involved region is usually oedematous; initially erythema and swelling may vary in intensity. In some patients, the cutaneous manifestations are confined to a heel that is swollen, sometimes discoloured and painful (Asbrink et al.1993). After the initial months to years, the oedema slowly vanishes and gradually atrophy becomes more and more prominent. The skin becomes increasingly vulnerable, thin and wrinkling, with prominently visible underlying vessels. When exposed to a cold environment, the skin becomes pronouncedly bluish. Band-like fibrous indurations may occur in the involved regions, usually in ulnar or tibial regions, or they may be nodular, preferably localised prepatellarly or next to the olecranon (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Müllegger 2004). In some cases of ACA, sclerotic lesions are clinically and histologically indistinguishable from localised scleroderma (morphea) or lichen sclerosus et atrophicus. About every tenth patient with typical inflammatory ACA also has a lichen sclerosus et atrophicus-like lesion (Asbrink and Hovmark 1987), and the histopathological picture of some of these patients is compatible with that of lichen sclerosus et atrophicus (Asbrink, Hovmark and Olsson 1986, Asbrink et al.1986). Peripheral nerves and joints are quite often involved in the regions of affected skin (Asbrink and Hovmark 1988). The majority of untreated patients with ACA have some kind of mostly mild or moderate neuropathy, as indicated by clinical and/or neurophysiological examination (Kristoferitsch et al.1988). Sensory and motor mononeuropathy or polyneuropathy or patchy dysaesthesia may develop at the site of the cutaneous lesions. Patients with ACA complain of hyperaesthesia/dysaesthesia, muscle cramps, muscle weakness and/or sensations of heaviness, mainly in the affected limb(s). Central nervous system (CNS) involvement in patients with ACA appears to be rare. In about one-fifth of patients with long-lasting ACA, subluxation and/or luxation of the small joints of hands or feet occur. A smaller proportion of patients with long-lasting disease show periosteal thickening of bones similar to dactylitis syphilitica in the late phase of syphilis (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986). Bursitis of the knee or elbow, epicondylitis, retro- or subcalcaneal bursitis and Achilles tendinitis may precede or accompany ACA (Asbrink and Hovmark 1987; Herzer 1993). The proper diagnosis of ACA is based on clinical, serological and histological criteria. Absence of IgG antibodies to B. burgdorferi s.l. in a patient with clinically suspected ACA requires reconsideration of the diagnosis because ‘seronegative’ ACA patients are almost non-existent (Kristoferitsch et al.1988; Asbrink, Hovmark and Weber 1993). Histological examination of the involved skin additionally consolidates the diagnosis. ACA lesions are infiltrated throughout the dermis with CD8+ and CD4+ T cells along with smaller numbers of B cells and abundant plasma cells (Müllegger et al.2007). Routine laboratory tests are usually in the normal range and thus not of substantial diagnostic help. The diagnosis of ACA can be further supported by the isolation of B. burgdorferi s.l. from lesional skin, which may be successful in about one-third of patients without previous antibiotic treatment (Ružić-Sabljić et al.2002). ACA should be considered as a possible diagnosis in a patient with bluish-red discolouration of a limb with or without swelling and/or atrophy (Müllegger 2004). Differential diagnoses or more often false interpretation of ACA skin lesions on the lower extremities are vascular insufficiency such as chronic venous insufficiency, superficial thrombophlebitis, hypostatic eczema, arterial obliterative disease, acrocyanosis, livedo reticularis, lymphoedema, ‘old skin’ or chilblains. Fibrous nodules may be misinterpreted as rheumatoid nodules and gout or even as erythema nodosum. Other skin manifestations of potential borrelial aetiology Scleroderma circumscripta and lichen sclerosus et atrophicus A borrelial aetiology of scleroderma circumscripta and lichen sclerosus et atrophicus, sclerotic skin lesions of unknown aetiology, has been implicated on the basis of humoral and cellular immune responses to B. burgdorferi s.l., on immunohistological findings and on demonstration of borrelial DNA in and isolation of B. burgdorferi s.l. from lesional tissue (Aberer et al.1987; Weber, Preac-Mursic and Reimers 1988; Breier et al.1999). However, proof of the aetiological role of B. burgdorferi s.l. in these skin disorders has not yet been established (Müllegger 2004). It should also be emphasised that sclerotic lesions that are clinically and histologically indistinguishable from localised scleroderma (morphea) or lichen sclerosus et atrophicus develop in about 10% of patients with typical inflammatory ACA (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Asbrink, Hovmark and Weber 1993). Cutaneous lymphoma Seropositivity, demonstration of borrelial DNA in 9 out of 50 (18%) of European patients with various types of primary cutaneous B-cell lymphoma and isolation of B. burgdorferi s.l. from skin lesions of two patients have suggested a possible association between primary cutaneous B-cell lymphomas and B. burgdorferi s.l. infection (Cerroni et al.1997; Kütting et al.1997). Further, the results of a case–control study in Denmark and Sweden suggest an association between B. burgdorferi s.l. infection and risk of mantle-cell lymphoma (Schöllkopf et al.2008). However, researchers from the USA did not find any such association in molecular or epidemiological studies (Munksgaard et al.2000; Wood et al.2001). Although the association has not been scientifically confirmed, the European Organization for Research and Treatment of Cancer and the International Society for Cutaneous Lymphoma suggest in a consensus paper that cutaneous marginal-zone lymphoma in European areas endemic for B. burgdorferi s.l. infection should be treated with antibiotics (Senff et al.2008). However, the efficacy of antibiotic treatment in borrelia-associated primary cutaneous marginal-zone lymphoma is poorly documented. Lyme neuroborreliosis LNB is the most common extracutaneous manifestation of Lyme borreliosis in Europe (Berglund et al.1995). LNB appears mostly early, during the first few weeks or months after infection, only rarely appearing late in the course of Lyme borreliosis. Early LNB typically shows lymphocytic meningitis and involvement of cranial and peripheral nerves. Case 6. A 43-year old farmer—who remembered several tick bites each year—became unwell in the middle of July. He suffered from myalgia, joint pain and mild headaches, was tired and occasionally very sleepy. At the end of September, after a short improvement for about 3 weeks, he developed chest pain, which expanded in extent during the first few days and became more and more intense. He reported an approximately 25 cm wide belt with a burning sensation over the upper part of the abdomen and lower part of the thorax that became worse during the night. It was hard for him to move because of the pain. He became impatient, agitated and experienced episodes of weeping for no obvious reason. He felt exhausted and totally without willpower. Problems were especially severe at night. For nearly 4 weeks, he was almost sleepless. There was no fever, no headache and no nausea. He visited his doctor several times but examinations revealed no abnormality. Sedatives and painkillers did not bring any relief. At the end of September, a day before admission to the hospital, he noticed that he was not able to close his left eye, to raise his left eyebrow, to frown on the left side of his forehead and that the left side of his mouth was not moving properly. On admission to hospital, the patient moved slowly and very carefully; he was in distress and seemed to be exhausted. He had left-sided peripheral facial palsy, but no other significant abnormality was found. Meningeal signs were not expressed. Results of the blood tests were within normal limits. CSF was clear, open pressure was normal. CSF leukocyte count was 114 × 106/l (96% lymphocytes), protein concentration 0.64 g/l (normal < 0.45 g/l), while concentrations of CSF and blood glucose were in normal range (3.6 and 4.9 mmol/l, respectively). Comment: Typical presentation of meningoradiculoneuritis (Gadin-Bujadoux-Bannwarth) syndrome with radicular pain, peripheral facial palsy and lymphocytic pleocytosis. The syndrome has been known in Europe for more than 90 years, i.e. well before the discovery of Lyme disease in the USA. Borrelial aetiology was definitely established by the isolation of B. burgdorferi s.l. from CSF. Meningoradiculoneuritis is the most prominent clinical manifestation of LNB in adult patients in Europe. It begins gradually with increasing pain, later on accompanied by palsies and other neurological signs and symptoms that will, if untreated, not diminish for many weeks (Kristoferitsch, Spiel and Wessely 1983; Pachner and Steere 1985; Kristoferitsch 1989, 1991; Hansen 1994; Stanek et al.2012; Ogrinc et al.2016) (Fig. 8). Radicular pain is the most pronounced clinical symptom of meningoradiculoneuritis; it is usually severe and most intense during the night. In children isolated meningitis and peripheral facial palsy are more common than in adults. In addition, involvement of motor nerves may lead to paresis (Kristoferitsch 1991; Hansen 1994; Hansen, Crone and Kristoferitsch 2013). Figure 8. View largeDownload slide Onset, duration and intensity of signs/symptoms in the spontaneous untreated course in patients with meningopolyneuritis (Kristoferitsch 1989). Figure 8. View largeDownload slide Onset, duration and intensity of signs/symptoms in the spontaneous untreated course in patients with meningopolyneuritis (Kristoferitsch 1989). Up to 10% of European patients with untreated meningopolyneuritis develop signs and symptoms of disseminated encephalomyelitis that may in some respects resemble those seen in multiple sclerosis (Kristoferitsch 1991). Case 7. A 13-year-old boy felt completely well during the first few weeks after a tick bite. However, 6 days after the bite he noticed a small redness at the site of the bite on his right thigh. In the next 2 weeks, the redness gradually increased in size to reach diameter of about 30 × 20 cm, clearing centrally and becaming ring-like. After 3 weeks, it spontaneously disappeared. Six weeks after the tick bite, headaches, nausea, vomiting and low fever appeared. The patient became sensitive to light and had pain when moving the eyes. The headache was predominantly frontal and varied in intensity. Five days later, he was admitted to the hospital due to the suspicion of aseptic meningitis. The only abnormalities found on admission were that he looked tired, had a body temperature of 38.3°C and had mildly expressed nuchal rigidity. CSF examination revealed findings consistent with lymphocytic meningitis: 165 × 106/l leukocytes (85% lymphocytes), protein concentration of 0.76 g/l, glucose in CSF 2.8 mmol/l and blood sugar 5.4 mmol/l. The diagnosis of borrelial meningitis was indicated by the history of EM and was further supported by the demonstration of serum antibodies to B. burgdorferi s.l. as well as detection of intrathecal synthesis of specific antibodies. The patient was treated with doxycycline 100 mg bid for 14 days and had an uneventful recovery. Comment: Characteristic presentation of borrelial CNS involvement in a child. Patients with borrelial meningitis usually suffer from mild intermittent headache, resembling relatively mild but unusually protracted viral meningitis with intermittent improvements and deterioration. Excruciating headache occurs exceptionally. In adult patients, fever, nausea and vomiting and meningeal signs are usually absent (Kristoferitsch 1991; Hansen 1994; Stanek and Strle 2003). In contrast, there is an abnormal CSF finding: lymphocytic pleocytosis up to several hundred × 106 cells/l. Protein concentration is normal or slightly to moderately elevated; glucose concentration is usually normal or mildly depleted. Case 8. An 11-year-old girl was bitten by a tick while collecting blueberries in June. No skin lesion developed at the site of the bite. On one evening, 5 weeks later, tingling and a ‘wooden’ sensation on the left side of her face occurred, and when she woke up on the next morning, she couldn’t close her left eye, nor raise the left eyebrow nor wrinkle the skin of her left forehead, she was not able to whistle and her left oral angle was immobile. Three days later, similar changes occurred on the other side of her face. She had no headache, no vomiting nor fever. At examination bilateral peripheral facial palsy was established. Meningeal signs were absent; basic laboratory blood tests were in normal range. CSF examination revealed normal opening pressure. CSF was clear with 108 × 106/l leukocytes (84% lymphocytes); the protein and glucose concentrations were normal. She was treated with i.v. ceftriaxone for 14 days and completely recovered after 3 months. Comment: In about half of patients with borrelial meningitis, peripheral facial palsy develops. In some patients, the paralysis is bilateral; in such cases, pareses usually do not appear at the same time. Patients often report a tingling sensation on the affected side and pain around the ear or jaw. Disorder of taste is rare (facial nerves are usually affected distally from the branching of the chorda tympani nerve). Palsies are of sudden onset, lasting from a few days to several months (average 8 weeks); they usually heal spontaneously and completely. Any cranial nerve may be affected in LNB but facial nerves are most frequently involved, resulting in unilateral or bilateral peripheral facial palsy (Kristoferitsch 1991; Halperin and Golightly 1992; Hansen 1994; Christen 1996; Lotrič-Furlan et al.1999; Eiffert et al.2004; Hansen, Crone and Kristoferitsch 2013). In an endemic region, peripheral facial palsy is associated with Lyme borreliosis in about 20% of adult patients and 25% of children (Lotrič-Furlan et al.1999; Strle and Stanek 2009). Lymphocytic pleocytosis is often seen in patients with borrelial peripheral facial palsy, although signs or symptoms of meningitis are absent (Lotrič-Furlan et al.1999). Borrelial peripheral facial palsy responds very well to antibiotic treatment but prognosis is also good in untreated patients (Pachner and Steere 1985; Hansen 1994). However, in clinical and neurophysiological examination, mild sequelae were found in about half of Swedish children who had borrelial peripheral facial palsy 3–5 years earlier (Bagger-Sjobak et al.2005). Results from another Swedish study showed that about 20% of children with acute facial palsy have permanent mild-to-moderate dysfunction of the facial nerve without other neurological symptoms or health problems, and that antibiotic treatment seems to have no correlation with the clinical outcome of peripheral facial palsy (Skogman, Croner and Odkvist 2003). Shortly after onset of neurological symptoms, intrathecal synthesis of antibodies may not be detectable and CSF pleocytosis may be absent especially in children with isolated facial palsy (Millner et al.1989). Involvement of most other cranial nerves has been described, particularly nervus oculomotorius, n. abducens and n. vestibulocochlearis. Clinical diagnosis of LNB is best supported by a preceding or accompanying EM, which is the case in 34–64% of patients with meningopolyneuritis (Stiernstedt et al.1985; Kristoferitsch 1989; Pfister, Kristoferitsch and Meier 1993; Strle et al.2006; Ogrinc et al.2016). A close topical association between the cutaneous region of the tick bite, subsequent EM and the radicular lesion has been established in European patients (Kristoferitsch et al.1983; Pfister et al.1987). An unusual manifestation of LNB is pseudotumour cerebri which is seen primarily in children (Steenhoff et al.2006; Feder 2008). In the USA, the most common LNB disorder is lymphocytic meningitis. Encephalitis resulting from a B. burdorferi s.l. infection seems to be extremely rare (Halperin 2008). Subtle encephalopathy has been reported predominantly by American authors (Logigian, Kaplan and Steere 1990). LNB in Europe is most often caused by B. garinii, less frequently by B. afzelii and B. burgdorferi and only exceptionally by other genospecies (Fig. 2) such as B. valaisiana, B. bissettii or yet unidentifiable species (Hitzo-Teufel et al.1996; Peter et al.1997; Strle et al.1997, 2006; Lebech et al.1998; Ryffel et al.1999; Ružić-Sabljić et al.2001; Ornstein et al.2002; Fingerle et al.2008; Ogrinc et al.2013, 2016). The clinical presentation of patients with a CSF culture-proven B. garinii LNB is different from that of patients with a B. afzelii LNB (Strle et al.2006). Borrelia garinii causes what, in Europe, is diagnosed as typical early LNB (i.e. painful meningoradiculoneuritis or Bannwarth syndrome), whereas the clinical features of CNS involvement associated with B. afzelii are much less specific and more difficult to diagnose since these patients rarely report radicular pains and have express meningeal signs. In contrast to the B. garinii group, the large majority of the B. afzelii group did not fulfill European criteria for LNB (Strle et al.2006). The findings of the study might indicate that, although B. afzelii is able to pass through the blood–brain barrier, it has restricted capability to initiate a substantial inflammation of the CNS. The significance of this genospecies in LNB remains to be elucidated. Histopathological findings in the CNS are limited. In peripheral neuropathy accompanying ACA, lymphocytes and plasma cells are present around blood vessels in the perineurium, with occasional sparse lymphocytes in vessel walls which show no signs of necrosis but may become thickened and obliterated, thrombosis may develop (de Koning and Duray 1993). Fibres within the nerve eventually lose myelin. The most striking finding is axonal degeneration (Kristoferitsch et al.1988; de Koning and Duray 1993; Hansen, Crone and Kristoferitsch 2013). Late LNB is most probably very rare. The only exception is peripheral neuritis in association with ACA. Peripheral neuritis occurs in more than half of patients with long-lasting ACA (Kristoferitsch 1991, 1993). Careful sight of the literature suggests that peripheral neuritis without ACA is an extremely rare condition, if it exists at all (Hansen, Crone and Kristoferitsch 2013; Wormser et al.2017). The diagnosis of early LNB should be based on clinical characteristics, the presence of lymphocytic pleocytosis and demonstration of CNS borrelial infection, as evidenced by intrathecal production of antibodies against B. burgdorferi s.l. (Wilske et al.1986; Brouqui et al.2004; Aguero-Rosenfeld et al.2005; Strle et al.2006; Mygland et al.2010). Isolation of borreliae from the infection site would be the most reliable method of diagnosing LNB, but unfortunately isolation from CSF or demonstration of borrelial DNA in CSF samples is limited by low sensitivity. Further, procedures for DNA detection are not standardised and may give false-positive results (Wilske et al.2000; Brouqui et al.2004; Aguero-Rosenfeld et al.2005; Strle et al.2006; Cerar et al.2008; Stanek et al.2012). In everyday European clinical practice, demonstration of intrathecally synthesised antibodies to B. burgdorferi s.l. has been established for the diagnosis of LNB. However, physicians should be aware that intrathecal synthesis may not be demonstrable shortly after the onset of LNB (Hansen 1994; Aguero-Rosenfeld et al.2005; Strle et al.2006; Cerar et al. 2010; Stanek et al.2011, 2012, 2014). In the presence of strong clinical evidence together with CSF pleocytosis and preceding EM, the clinician should stay with the clinical diagnosis despite absence of proof of intrathecal antibody production. This may be demonstrable in later samples. A reliable diagnosis of a borrelial infection involving the peripheral nervous system strongly depends upon the concomitant presence of LNB and/or some other manifestation of Lyme borreliosis such as EM or ACA. Differential diagnosis comprises a list for each main manifestation of LNB, such as meningitis, radiculoneuritis, cranial nerve involvement and so forth. However, an exact medical history and meticulous clinical examination can often substantially narrow the possibilities. Lyme carditis Case 9. A 28-year-old previously healthy housewife was bitten by a tick in the middle of May. No skin lesion developed at the site of the bite. At the end of May, intermittent migratory myalgia and arthralgia appeared and a month later burning belt-like pain in the middle of the chest emerged; the pain was very severe and nearly unbearable at night. The patient was not able to sleep and was suicidale due to pain. She also had difficulties with concentration and thinking and was afraid of making mistakes when performing even the simplest daily tasks. She did not have headache, nausea or fever. On 27 August, she woke up with pressing retrosternal pain spreading to the neck. She was dizzy when standing up but dizziness disappeared when she lay down. She was examined at the emergency department and admitted to hospital. ECG showed second degree atrio-ventricular (A-V) block. Ultrasound examination of heart revealed no substantial abnormalities. In the evening of the next day, bradycardia (34/min) appeared; complete heart block with narrow QRS complexes was established and a transitory pacemaker was inserted. In the following 2 days, the patient had changing third to second degree A-V blocks. On 31 August, the block was predominantly of second degree and occasionally also of first degree, and on 1 September only first degree A-B block was registered. In the following week, P-Q interval shortened from 320 ms to normal values. The further clinical course was smooth and the outcome was uneventful. From the second day of hospitalisation, the patient was treated with ceftriaxone 2 g i.v./day for 14 days. The diagnosis of Lyme carditis was substantiated by high levels of IgG serum antibodies to B. burgdorferi s.l., and by demonstration of coexisting LNB (CSF examination, performed due to radicular pains, showed lymphocytic pleocytosis and intrathecal synthesis of IgG antibodies to B. burgdorferi s.l.). Comment: A typical course and outcome of Lyme carditis. In patients with suspected Lyme carditis, the diagnostic approach should include active search for other manifestations of Lyme borreliosis (such as EM and LNB) and exclusion of other explanations for cardiac abnormalities. Heart involvement related to a borrelial infection usually presents with the acute onset of varying degrees of intermittent atrioventricular (A-V) heart block, sometimes in association with clinical evidence of myopericarditis (Steere et al.1980; McAlister et al.1989). It is often coincident or following other features of Lyme borreliosis such as EM, LNB or arthritis (Steere et al.1980; Van der Linde 1991). The frequency of heart involvement in relation to the other manifestations of Lyme borreliosis appears to be very low (Rubin et al.1992; Sigal 1995; Wormser et al.2006; Steere et al.2016). No evidence of carditis was found among 233 cases with definite Lyme borreliosis in two prospective studies evaluating a recombinant OspA vaccine in the USA (Sigal et al.1998; Steere et al.1998). In an epidemiological study in southern Sweden, only 7 of 1471 (0.5%) patients with Lyme borreliosis had carditis (Berglund et al.1995) and at the Ljubljana Lyme borreliosis clinic, where about 600–1000 patients with different manifestations of Lyme borreliosis are diagnosed each year, Lyme carditis was diagnosed in less than 0.5% of cases (unpublished data). Histopathology shows interstitial infiltrates of lymphocytes and plasma cells involving the myocardium, pericardium and endocardium. Muscle fibres are usually intact (Steere et al.1980; Reznick et al.1986). The heart conducting system may show localised oedema and slight lymphocytic infiltration of sinoatrial and A-V nodes, focal oedema in the bundle of Hiss, fibrotic lesions, and vasculitis of small and large intramyocardial vessels (de Koning and Duray 1993; Fish, Pride and Pinto 2008). Spirochaetal forms have been found in endomyocardial biopsy (de Koning et al.1989), and borreliae have been cultured from biopsy specimens (Stanek et al.1990). Lyme carditis occurs between June and December, usually within 2 months after the onset of infection, men being affected more often than women (Steere et al.1980; McAlister et al.1989). The most common complaints in Lyme carditis include mild dizziness, syncope, dyspnoea, palpitations and/or chest pain. The prognosis is usually favourable (Sigal 1995). Hospitalisation is needed for patients with first-degree A-V block with P-Q interval longer than 0.30 s, second- or third-degree A-V blocks, quickly changing A-V blocks or haemodynamically precarious arrhythmias (van der Linde 1991). In a case of complete heart block, insertion of a temporary heart pacemaker may be life saving. Diffuse ST segment and T wave changes on surface electrocardiograms were noted in the majority of a first series of patients with Lyme carditis (Steere et al.1980). In most cases, myocardial dysfunction is mild and self-limited (Steere et al.1980; Midttun et al.1997). The isolation of B. burgdorferi s.l. from an endomyocardial biopsy specimen of a 54-year-old man with a 4-year history of dilated cardiomyopathy (Stanek et al.1990) inspired the hypothesis of a causative role in chronic heart failure. However, there is as yet no convincing evidence of such an association. Diagnosis of Lyme carditis should be based on established conduction disturbances (electrocardiographic and/or electrophysiological findings) and/or myo(peri)carditis (demonstrated pathohistologically in endomyocardial biopsy specimens, or suggested by electrocardiographic, echocardiographic and/or MRI findings) (Strle and Stanek 2009). The diagnosis also requires corroboration by demonstration of borrelial infection; in practice the presence of typical manifestation(s) of Lyme borreliosis such as EM or LNB is the most reliable. A diagnosis of Lyme carditis should be further substantiated by the absence or exclusion of other (obvious) explanations for cardiac abnormalities. Lyme arthritis Case 10. A 56-year-old accountant developed migratory myalgias and arthralgias in mid of September that he attributed to pronounced physical activities during the previous months. At the beginning of October, he woke up with severe pain in the right knee. The joint was heavily swollen, warm, skin colour was normal. The pain, which was quite severe at rest, deteriorated with movement. He was treated with anti-inflammatory drugs. Five days later, and 2 days before right knee swelling vanished, effusion of his left knee appeared, and somewhat later the right ankle became painful and swollen. The duration of attacks of individual joint involvement was 5–14 days. Basic laboratory tests disclosed normal results with the exception of moderately elevated C-reactive protein (CRP) concentration (56 mg/l). Synovial fluid examination of the right knee revealed elevated leukocyte counts (48 × 109/l) with a predominance of polymorphonuclear leukocytes (74%). Synovial fluid culture was negative for the presence of bacteria, and no crystals were found. However, the patient had high serum IgG antibody levels to B. burgdorferi s.l., and the presence of borrelial DNA in the synovial fluid was demonstrated by PCR. The patient was treated with doxycycline 100 mg bid for 4 weeks. Before the end of antibiotic therapy, attacks of arthritis vanished and later on he only occasionally had mild-to-moderate arthralgias of large joints. Comment: A characteristic course and outcome of Lyme arthritis. Lyme arthritis is mostly monoarticular or oligoarticular, typically involving the knee. The frequency of this manifestation is about 10% of all Lyme borreliosis manifestations according to studies in the USA (Steere, Schoen and Taylor 1987; Steere 1989; Gerber et al.1996; Sigal et al.1998; Steere 2001; Krause et al.2002). In Europe, the aetiological relationship of certain cases of arthritis to a B. burgdorferi s.l. infection was not considered before a link was established in the USA. Nevertheless, European dermatological literature had described a relationship between joint and bone abnormalities and ACA long before, as emphasised by the term ‘akrodermatitis atrophicans arthropathica’ (Gans and Landes 1952), and joint symptoms had been mentioned in case reports on erythema chronicum migrans and lymphocytic meningitis (Bannwarth 1941; Schaltenbrand 1949; Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Herzer 1993). However, Lyme arthritis has ever since been considered a less common manifestation in Europe than in the USA. Seven per cent of 1491 patients diagnosed with Lyme borreliosis in a study from southern Sweden had Lyme arthritis (Berglund et al.1995), and about 3% of patients who presented with Lyme borreliosis at the outpatients clinic in Ljubljana had clinical arthritis (see Fig. 4). The isolation rate of borreliae from joint fluid and synovia is very low; thus, data on the infecting agent are based predominantly on molecular detection of borrelial DNA in synovial fluid or synovial tissue. The genospecies identified in Lyme arthritis cases in Europe were B. burgdorferi in three cases from the Netherlands (van der Heijden et al.1999), and B. burgdorferi in nine cases and B. garinii in two cases from France (Jaulhac et al.2000; Limbach et al.2001). The synovial fluid from 13 of 20 patients with the diagnosis of Lyme arthritis in Germany was processed for borrelial DNA by OpsA typing and revealed B. burgdorferi in 27%, B. afzelii in 33% and B. garinii in 40% (Vasiliu et al.1998), with no predominance of any particular genospecies. Similar results were obtained in another study from Germany where B. burgdorferi and B. garinii were each detected in the synovial fluid of three patients and B. afzelii was detected in one (Eiffert et al.1998). B. burgdorferi was cultivated from the synovial fluid of an Austrian patient when Lyme arthritis developed following an autologous chondrocyte transplant (Marlovits et al.2004). B. bavariensis was detected in the synovial fluid of the knee and ankle joint of an 11-year-old boy who suffered from intermittent arthritis over 5 years (Markowicz et al.2015). Acute arthritis results from Borrelia-induced infiltration of mononuclear cells into the synovial tissue and the accumulation of neutrophils, immune complexes, complement and cytokines in the synovial fluid. In untreated Lyme arthritis, host factors involved may include autoantigens like endothelial cell growth factor and apolipoprotein B-100, arthritogenic factors such as TLR2 and MyD88, adhesion molecules P66 that bind the extracellular matrix, decorin-binding proteins A and B, Bgp and BKK, T and B-cell responses to annexin A2, and annexin A2 autoantibodies (Coburn, Fischer and Leong 2005; Guerau-de-Arellano and Huber 2005; Drouin et al.2013; Londoño et al.2014; Crowley et al.2015; Pianta et al.2015). In addition, matrix metalloproteinases may be involved in the pathogenesis of erosive processes in the joint in long-standing infection and possibly also in antibiotic-refractory arthritis (Hu et al.2001; Behera et al.2005; Crowley et al.2016). Excessive TH17 responses may be disadvantageous by contributing to autoimmune responses associated with antibiotic-refractory Lyme arthritis (Strle et al.2017). Persistent or antibiotic-refractory Lyme arthritis may be observed in a subset of patients who have already received standard antibiotic treatment. Models for the immune-pathogenesis proposed comprise persistent infection, T-cell epitope mimicry and bystander activation of T cells. However, none of these has enabled a complete explanation for all patients. The aetiology is most probably multifactorial and may vary from patient to patient (Steere and Glickstein 2004; Puius and Kalish 2008). The main and the most important joint manifestation of Lyme borreliosis is arthritis. Arthralgia may precede, accompany or follow arthritis but may sometimes be the only rheumatic manifestation of Lyme borreliosis. Indicative of Lyme arthritis in Europe are the succession or coexistence of intermittent attacks of musculoskeletal pain and arthritis (Herzer 1993). In a subset of patients, episodes of severe pain in joint and periarticular sites may precede arthritis for several weeks or months, or may precede and continue after arthritis, or may develop with arthritis. Episodes of arthralgias may alternate with attacks of arthritis. Large joints are predominately affected but also small joints in an often migratory pattern; however, involvement of only small joints is very rare. Mostly only one or two sites are affected at any one time (Herzer 1993). In the early studies, arthralgias were reported in 48% of patients with EM in North America (Steere et al.1983a) but in only 22% at the most in European patients (Weber and Neubert 1986). In a later study, 40% of patients with B. burgdorferi EM in New York State reported arthralgias prior to treatment, whereas only 27% of Slovenian patients with B. afzelii EM complained about arthralgias (Strle et al.1999). In another study from Ljubljana/Slovenia in 231 patients with culture-confirmed EM, only 12% reported arthralgias that were mild to moderately severe (Strle et al.1996b). Arthralgias usually vanish during the first few weeks after standard treatment (Cerar et al. 2010). The incubation period for Lyme arthritis, from tick bite to clinical manifestation, cannot be easily assessed. In patients from North America who had EM without antibiotic treatment and were followed up for years, arthritis occurred from 4 days to 2 years after onset of infection, with a mean of 6 months (Steere, Schoen and Taylor 1987). In a European series of patients, the period from tick bite or EM to the onset of arthritis ranged from 10 days to 16 months, with a mean of 3 months (Herzer 1991). Lyme arthritis can be preceded or accompanied by other manifestations of Lyme borreliosis. EM before Lyme arthritis has been reported in 25% of patients in the USA (Steere et al.1977b). In patients in Germany, EM has been reported in 32%, LNB in 22%, ACA in 8% and carditis in 1.5% (Herzer 1993). Results of a prospective epidemiological study of Lyme borreliosis in southern Sweden showed that of 98 patients diagnosed with Lyme arthritis (7.5% of all cases), 65 presented with arthritis alone; in the remaining patients, arthritis was associated with EM in ten, LNB and ACA in eight each, and borrelial lymphocytoma in one. Six patients with arthritis had two additional main manifestations of Lyme borreliosis (Berglund et al.1995). For clinical diagnosis, it should be considered that Lyme arthritis usually consists of intermittent attacks of inflammation of one or a few large joints and is often preceded by intermittent migratory joint pain. Joint involvement is usually asymmetric, the onset of arthritis is acute and with effusion, and skin over the affected joint is warm but of normal colour (Steere, Schoen and Taylor 1987). The knee is most often involved. Shoulder, ankle, elbow, temporomandibular joint, wrist and hip are affected in the range of 28%–43%, and metacarpophalangeal, proximal interphalangeal, distal interphalangeal and metatarsophalangeal joints are involved in 11% (Steere, Schoen and Taylor 1987). Similarly, in the European series of 65 patients, involvement of the knee was by far the most common, followed by ankle, wrist, finger, toe and elbow; heel swelling was found in 9% and dactylitis in as many as 23% (Herzer 1991, 1993). In the patients with knee involvement alone, Baker cysts were found in 50%. However, some patients with pronounced knee effusions have only mild pains (Steere, Schoen and Taylor 1987). Joint inflammation usually lasts a few days to weeks, sometimes several months (Steere, Schoen and Taylor 1987). The course of Lyme arthritis is usually recurring and may continue for several years. In the beginning, the attacks of arthritis are more frequent and short, later they may be more prolonged and about 10% of patients develop chronic arthritis with duration of a year or longer (Steere, Schoen and Taylor 1987; Rees and Axford 1994). Fatigue, malaise, low fever or night sweats may accompany Lyme arthritis in a small proportion of patients (Herzer 1991, 1993). Routine laboratory parameters are often completely normal in Lyme arthritis. Concentration of CRP is usually in the normal range. The pronounced elevation of laboratory inflammation parameters in a patient with arthritis points strongly against Lyme arthritis. Some patients have slightly elevated counts of white blood cells, and some elevated serum IgM. Cryoglobulins and circulating immune complexes may be present. Rheumatoid factors and antinuclear antibodies are usually negative. Synovial fluid shows elevated white cell counts with a range of 0.5–110 × 109 cells L−1, with predominance of polymorphonuclear leukocytes up to about 80% (Steere et al.1977a,b; Steere, Schoen and Taylor 1987; Herzer 1991, 1993; Rees and Axford 1994). Total protein concentration commonly ranges from 3.5 to 5.6 g L−1 (Steere et al.1977a,b; Herzer 1991; Rees and Axford 1994). Cryoglobulins and abnormal C1q binding consistent with antigen–antibody complexes are commonly present in synovial fluid (Hardin and Steere 1979; Steere et al.1979). Specific radiographic findings for Lyme arthritis have not been reported (Lawson and Steere 1985). Serum IgG antibodies to B. burgdorferi s.l. are almost always present in high titres in patients with Lyme arthritis, negative IgG serology basically ruling the diagnosis out (Aguero-Rosenfeld et al.2005; Puius and Kalish 2008). Serological investigation of synovial fluid is of no value because of the absence of a blood–synovial barrier; IgG antibody concentration in serum and synovial fluid will be the same. What would additionally support the diagnosis of Lyme arthritis is the demonstration of borrelial DNA in synovial fluid or in synovial tissue. Diagnosis of Lyme arthritis is based on the medical history (other manifestations of Lyme borreliosis such as EM, LNB or ACA), clinical features, laboratory findings, exclusion of other causes of arthritis and demonstration of serum IgG antibodies to B. burgdorferi s.l. (Nadelman and Wormser 1998; Strle 1999a; Steere 2001; Stanek and Strle 2003). One should nevertheless be aware that IgG seropositivity is not diagnostic for Lyme arthritis as it does not inform about active or past infection nor about the location of the disease process. Thus, PCR detection of borrelial DNA in synovial tissue or synovial fluid should always be attempted since its sensitivity is high, at up to 85% (Snydman et al.1986; Nocton et al.1994; Eiffert et al.1998; Vasiliu et al.1998; van der Heijden et al.1999; Jaulhac et al.2000; Aguero-Rosenfeld et al.2005; Wormser et al.2006). The differential diagnosis of Lyme arthritis includes inflammatory rheumatic diseases, bacterial (septic) arthritis, viral arthritis and crystal-induced arthritis (Steere, Schoen and Taylor 1987; Herzer 1991; Rees and Axford 1994). Other differential diagnoses include psoriatic arthritis, early rheumatoid arthritis and systemic lupus erythematosus in patients who have borrelial antibodies in serum. Musculoskeletal pain in Lyme borreliosis may be mistaken for psychogenic rheumatism or fibromyalgia. However, fibromyalgia is characterised by more generalised chronic pain and by symmetric tender points, and thus more often fibromyalgia in seropositive persons is often wrongly diagnosed as Lyme borreliosis (Herzer 1991). Eye involvement Eye involvement in the course of Lyme borreliosis appears to occur very rarely and is associated with EM, LNB or Lyme arthritis, although it can be the sole manifestation of the disease (Steere 1989; Strle 1994; Mikkila et al.2000). Often, the clinical ocular features may not be recognised (Karma et al.1995; Mikkila et al.1999; Colucciello 2001). Since human intraocular material is usually unavailable, serology remains the main diagnostic aid with all its interpretation problems. Onset of eye involvement is difficult to assess; the interval from EM may range from a few days to years. Conjunctivitis is apparently an early ocular manifestation whereas keratitis appears late in the course of Lyme borreliosis (Schönherr and Strle 1993). Primary borrelial-induced inflammation of the eye includes conjunctivitis, keratitis, iridocyclitis, retinal vasculitis, chorioiditis, optic neuropathy, episcleritis, panuveitis and panophthalmitis. Secondary effects are results of extra-ocular manifestations of borrelial infection, including pareses of certain cranial nerves, pseudotumour cerebri and orbital myositis (Steere et al.1985; Karma et al.1995; Mikkila et al.1999; Colucciello 2001; Carvounis, Mehta and Geist 2004; Mahne et al.2015). Inflammation of the eyes may lead to severe impairment or even complete loss of vision (Steere 1989; Schönherr and Strle 1993; Mikkila et al.1999, 2000; Colucciello 2001). The frequency of conjunctivitis associated with EM was 11% in patients in the USA, whereas in Europe the proportion was between 4% and 5% in Slovenian patients (Schönherr and Strle 1993). In later published cases of EM, conjunctivitis was reported only rarely or not mentioned at all. Ocular inflammation was diagnosed in 4% of children and adolescents who suffered from Lyme arthritis; the eye involvement comprised keratitis, anterior uveitis and uveitis intermedia (Huppertz, Munchmeier and Lieb 1999). Intraocular involvement resulting from borrelial infection has been described in 19 European patients. The borrelial aetiology was primarily based on seropositivity. Twelve of the patients had chorioiditis, three neuroretinitis, two bilateral retinal vasculitis, one bilateral iridocyclitis and one keratitis (Schönherr and Strle 1993). Other objective manifestation(s) of Lyme borreliosis were present in nine of these patients. Diagnosis of borrelial eye involvement should be based on medical history, complete physical (not only ophthalmological) examination and demonstration of borrelial infection. The differential diagnosis is broad (Schönherr and Strle 1993; Mikkila et al.2000; Strle and Stanek 2009; Mahne et al.2015). Other rare manifestations attributed to Lyme borreliosis A possible causative role of B. burgdorferi s.l. has been discussed for progressive facial hemiatrophia and eosinophilic fasciitis, also known as Shulman syndrome (Stanek et al.1987a,b; Granter et al.1994; Hashimoto et al.1996). In addition, there are case reports on patients with myositis (Reimers et al.1993), dermatomyositis (Horowitz et al.1994; Hoffmann et al.1995), nodular fasciitis (Schnarr et al.2002), panniculitis (Viljanen et al.1992) and osteomyelitis (Oksi et al.1994). There are also reports on the effect on individual organs or organ systems such as liver, lymphatic system, respiratory tract, urinary tract and genitalia (Steere 2001), but proof of the existence of such involvement in humans is weak. Lyme borreliosis during pregnancy There are no precise data on the natural course and outcome of Lyme borreliosis during pregnancy, but there is general acceptance that there are no substantial differences between pregnant and non-pregnant women with Lyme borreliosis, and that pregnant women treated for Lyme borreliosis have an outcome similar to women in the corresponding adult population (Maraspin and Strle 2009). Although it is well known that B. burgdorferi s.l. may be present in the blood early in the course of Lyme borreliosis, the consequences of this for the fetus are not clear cut (Maraspin et al.2011). In utero transmission of B. burgdorferi s.l. during pregnancy, resulting in fetal involvement, has been reported in humans (Schlesinger et al.1985; Markowitz et al.1986; MacDonald, Benach and Burgdorfer 1987; Weber, Preac-Mursic and Reimers 1988) and in animals such as cows, horses, dogs and mice (Gustafson et al.1993; Silver et al.1995). Nevertheless, reports of fetal involvement in humans are limited to the description of single cases, and in some articles the proof of borrelial infection is imprecise by present standards. There are also no reliable studies on the outcome of Lyme borreliosis after treatment as for the non-pregnant population. The only published prospective study on treatment of Lyme borreliosis during pregnancy is a report on 58 consecutively enrolled patients treated for EM with ceftriaxone 2 g daily for 14 days (Maraspin et al.1996) and its extension with the addition of 47 further patients (Maraspin et al.1999a). According to these two reports, none of the 105 consecutive pregnant women so treated for EM developed any subsequent manifestation of Lyme borreliosis, and the outcome of their pregnancies was analogous to the outcome in pregnant women without Lyme borreliosis. The majority of patients treated for EM (93/105, 88.6%) gave birth at term to healthy babies with normal later psychomotor development. The other 12 (11.4%) pregnancies ended with abortion in two cases, preterm delivery in six cases and congenital abnormalities in four babies delivered at term. No causal relationship with borrelial infection was established in any of these 12 cases and in several of them acceptably reliable alternative explanations were found for the unfavourable outcomes (Maraspin et al.1996,1999a). Lyme borreliosis in an immunocompromised host Information on the course and outcome of B. burgdorferi s.l. infection in immunocompromised patients is limited. There is one comparative study available on the course and outcome of typical EM in 67 adult patients with underlying immune-compromised conditions and in 67 previously healthy age- and sex-matched individuals with EM. The duration of EM after starting antibiotic treatment was similar in the two groups, but early disseminated borrelial infection before treatment and treatment failure were found more often in immunocompromised patients than in the control group. The two groups of patients were treated with the same antibiotic regimen. Re-treatment was required in 19% of immunocompromised patients but in only 7% of patients in the control group. However, both groups had a favourable outcome of borrelial infection after 1 year (Maraspin et al.1999b). With respect to the heterogeneity of causes for immune compromisation, it appeared that the likelihood of developing disseminated infection or treatment failure may be higher among patients with haematological malignancies. It was concluded that although in the majority of immunocompromised patients with EM the management can be the same as in immune-competent patients with early Lyme borreliosis, more aggressive initial antibiotic treatment might be appropriate for some subgroups of patients with altered immunity, such as those with haematological malignancy (Maraspin et al.1999b). A more recent study on 53 patients with EM and underlying hematological malignancy revealed that disseminated early Lyme borreliosis and treatment failure were diagnosed in 7/53 (13.2%) of patients with haematological malignancy, but in 0/106 immunocompetent patients, that the complications were limited to patients with underlying lymphoid neoplasm (complications were present in 7/41 patients with lymphoid neoplasm and in 0/12 with underlying myeloid neoplasia) and that they were associated with receiving immunosuppressive drugs. However, again, the outcome after 1 year was excellent, indicating that the antibiotic treatment approach as used in immunocompetent patients with EM is effective in patients with underlying haematological malignancy (Maraspin et al.2015). In another trial, the outcome of treatment of EM was studied in 33 patients immunosuppressed for several reasons and in 75 otherwise healthy patients with EM. The two groups were matched for sex, age and antibiotic therapy. Comparison did not reveal any significant difference between the two groups. The authors concluded that immunosuppression apparently does not influence clinical presentation, response to therapy or production of antibodies to B. burgdorferi s.l. in patients with EM. Thus, it is not necessary to treat immunosuppressed patients with EM differently from immunocompetent patients (Fürst et al.2006). The fourth report is on six adult recipients of solid-organ transplants who had chronic drug-induced immunosuppression and presented with solitary EM. All these patients had a localised EM and a mild and smooth course of illness, as well as a favourable outcome after treatment with the same antibiotic regimens as used for immunocompetent patients (Maraspin, Ruzic-Sabljic and Strle 2006). Chronic Lyme borreliosis and ‘chronic Lyme’ Chronic Lyme borreliosis exists in Europe. However, the designation should be reserved for patients with objective manifestations of late Lyme borreliosis, caused by persistent infection with B. burgdorferi s.l. These patients typically present with ACA, chronic arthritis and very rarely with chronic LNB without ACA. The term chronic Lyme borreliosis should not be misused or erroneously used for symptoms of unknown cause, nor for well-defined illness unrelated to borrelial infection but with antibodies against B. burgdorferi s.l., nor for symptoms of unknown cause with antibodies against B. burgdorferi s.l. but no reliable history of Lyme borreliosis, and not for post-Lyme borreliosis syndrome (Wormser et al.2006; Feder et al.2007; Marques 2008). Aspects of laboratory diagnosis in Lyme borreliosis According to the principles of medical microbiology, the specific aetiology of any infectious disease is usually best determined by direct detection of the agent from the site of infection. Without this and without a specific marker obtained by clinical laboratory methods, full proof of the borrelial aetiology of any of the described disorders in Lyme borreliosis will not be possible. Will such an approach be straightforward in suspected Lyme borreliosis? At present, the clinical laboratory cannot confirm Lyme borreliosis from routine blood values. CRP values and white blood cell counts are usually in the normal range (Nadelman and Wormser 1998; Strle 1999a,b; Steere 2001; Stanek and Strle 2003; Strle and Stanek 2009; Stanek et al.2012; Ogrinc et al.2016). The promising cytokine CXCL13 appears not to be a specific marker for active Lyme borreliosis (Ljøstad and Mygland 2008; Schmidt et al.2011; Wutte et al.2011a,b; Cerar et al.2013). Nevertheless, the greater inflammatory potential of B. burgdorferi over B. afzelii and B. garinii has been demonstrated in vitro and in vivo (Strle et al.2009). Despite the marked impression of a typical EM, its histological picture is generally non-specific. Even in ACA and borrelial lymphocytoma, the histological picture, although supportive, is not sufficiently specific for unequivocal evidence. The characteristic CSF lymphocytic pleocytosis may be absent very early in the involvement of the CNS, particularly in children (Millner et al.1989) and in some patients with peripheral facial palsy. Common and supportive findings in patients with CNS involvement are intrathecal IgM and IgG production and oligoclonal IgG bands which are detectable for a few weeks or longer. The concentration of glucose in CSF is usually normal. Patients with ACA and longstanding peripheral polyneuropathy have—as a rule—normal CSF findings. Direct detection of the agent Culture.Borrelia burgdorferi s.l. strains can be grown in complex media (Barbour 1984; Preac-Mursic et al.1996). The success of cultivation depends on the clinical presentation and the type of specimen. For example, cultivation of B. burgdorferi s.l. from skin biopsies of EM is usually very successful, at 50%–80% (Ružić-Sabljić et al.2000,2002; Aguero-Rosenfeld et al.2005; Cerar et al.2010; Stupica et al.2012,2015; O’Rourke et al.2013; Strle et al.2013a). However, EM will usually be identified by inspection, and cultivation is only rarely requested. In CSF, the success of culture is usually around 10% to 15% or less, possibly increasing to 30% in children in the very early phase of neurological disorders (Millner et al.1989; Strle et al.2006; Ogrinc et al.2013, 2016). Borrelia burgdorferi s.l. strains have been isolated from the blood of patients with EM, most successfully in the USA, by using high-volume blood cultures (Wormser et al.2005), and also from cardiac tissue of patients with dilated cardiomyopathy (Stanek et al.1990) and synovial fluid of patients with Lyme arthritis (Marlovits et al.2004). However, the relatively sophisticated demands of B. burgdorferi s.l. culture would not be managed in most medical laboratories. Nucleic acid amplification techniques PCR methods are available for the detection of low copy numbers of the genus Borrelia and the genospecies of Lyme borreliae. Unlike culture, conventional PCR cannot explicitly establish whether or not an infection is active since PCR detects borrelial DNA of both viable and non-viable organisms. Whether PCR is a valuable tool particularly in the diagnosis of arthritis in Europe remains to be substantiated. In a study from North America, borrelial DNA could be detected in about 85% of synovial fluid samples and even more if the synovial membrane is examined (Nocton et al.1994). Urine has been investigated by several groups (Pleyer et al.2001; Aberer et al.2007); however, results are contradictory (Rauter et al.2005). Thus, PCR results should always be interpreted with caution and the clinical significance of a PCR-positive finding in urine remains to be established. It should be emphasised that a negative result for culture and/or PCR does not exclude active infection because both methods are dependent on sample success. Indirect detection of a Borrelia burgdorferi s.l. infection: serology The previously mentioned problems with direct detection procedures paved the way for the success of serological tests. Serum specimens are easily obtained and processed. Today, an uncountable number of commercial products are available for detection of IgG and IgM antibodies against B. burgdorferi s.l. Test systems now comprise numerous techniques including immunofluorescence, enzyme-linked immunosorbent assay (ELISA), chemiluminescence, luminex and immunoblot among others. ELISA is still the most frequently used test system. However, interest in more flexible multiplex detecting systems is increasing. Serodiagnosis of Lyme borreliosis is currently based on the two-tier testing procedure, meaning that positive and borderline results in a sensitive screening assay are tested for specificity in an immunoblot system. Most screening assays are either enriched with VlsE (variable-like sequence expressed) antigen or use VlsE or C6 as a single antigen for detection of specific IgG antibodies. OspC is used for detection of specific IgM antibodies, either as a single antigen or in a mixture with other antigens. VlsE and C6 were originally considered markers for active infection but the strong immune reaction to these antigens is also present in convalescent and healthy persons, and thus does not differentiate between active and past infection. Immunoblot (western blot) can characterise the immune responses to specific proteins of B. burgdorferi s.l. The interpretation criteria for immunoblot results are based on diagnostic antigens of which most were identified in the late 1990s (Hauser, Lehnert and Wilske 1999; Wilske et al.1999, 2000). Line blots using recombinant antigens are currently replacing immunoblots. The European Union Concerted Action on Lyme Borreliosis/EUCALB has conducted a multicentre study in order to elaborate standardisation of criteria for interpretation of immunoblot results in Europe. Although a set of eight bands were identified as significant in each participant laboratory, no single rule could be formulated for use across Europe (Robertson et al.2000). Recombinant immunoblots were expected to solve this problem (Wilske et al.1999). However, in terms of sensitivity and specificity, recombinant IgM blots in particular not infrequently produce false-positive results (Seriburi et al.2012; Wormser et al.2013). In another study, the diagnostic accuracy of a single-tier commercial C6 ELISA kit was compared with two-tier testing. The results showed that the C6 ELISA as a single-step serodiagnostic test provided increased sensitivity in early Lyme borreliosis with comparable sensitivity in later manifestations of Lyme borreliosis (Wormser et al.2013). The shortcomings of two-tier serological testing in Lyme borreliosis are thus obvious and include low sensitivity in early disease, increased cost, time and labour, and subjectivity in the interpretation of immunoblots (Wormser et al.2013). The results of several studies suggest that the ELISA systems that use Vlse and OspC as antigens for detecting Borrelia-specific IgG and IgM antibodies show sufficiently sensitivity and specificity to replace the two-tier test principle (Steere et al.2008; Branda et al.2011,2013; Wormser et al.2013,2014; Moore et al.2016). However, even if the two-tier principle is modified or abandoned, there is still no method or technique for identification of active infection. Assays such as the lymphocyte transformation test are recommended for the identification of active Lyme borreliosis even in seronegative cases. Critical evaluation, however, shows that this is not the fact (Dessau et al.2014). A substantial difficulty is the relatively high prevalence of antibodies to B. burgdorferi s.l. in the general population, which is not directly related to the prevalence of disease. Persons such as hunters continuously exposed to ticks show an age-related seroprevalence (Cetin et al.2006). After more than 20 years of ‘Lyme serology’, it often appears that for diagnostic purposes serology has created nearly as many problems as it has solved. The immune response to borrelial infection still requires further elucidation. However, demonstration of borrelial IgG antibodies remains an indisputable approach to support diagnosis of long-lasting clinically well-defined manifestations of Lyme borreliosis. Furthermore, serology for detection of intrathecal production of specific antibodies—expressed as the CSF/serum index or antibody index (AI)—is very beneficial in the diagnosis of LNB (Wilske et al.1986; Cerar et al.2010; van Burgel et al.2011; Djukic et al.2012; Stanek et al.2014; Ogrinc et al. 2015, 2016). The IgG-AI expresses the proportion of IgG antibodies against of B. burgdorferi s.l. in the total IgG content in the CSF compared with the serum. An index above 1.0 would, strictly mathematically, prove the intrathecal production of specific antibodies. With respect to small volume variations when diluting samples, an index of >1.4 is considered significantly elevated (Reiber and Peter 2001). Table 1 refers to recommendations listing the suspected clinical conditions and the weight of laboratory results required to confirm the clinical suspicion (Stanek et al.2011). Table 1. Laboratory support in the diagnosis of Lyme borreliosis; modified according to the clinical case definitions in Lyme borreliosis (Stanek et al.1996, 2011). Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy a Specific antibody levels in serum may increase in response to progression of infection or treatment, or may decrease due to abrogation of the infection process. Samples collected a minimum of 3 months apart may be required in order to detect a decrease in IgG levels. b Intrathecally produced specific antibodies are determined by investigating simultaneously drawn samples of CSF and serum. View Large Table 1. Laboratory support in the diagnosis of Lyme borreliosis; modified according to the clinical case definitions in Lyme borreliosis (Stanek et al.1996, 2011). Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy Initial clinical diagnosis Essential laboratory evidence Supporting laboratory evidence Erythema migrans None if typical Culture from skin biopsy; seroconversion of specific serum IgG antibodies or presence of specific IgMa Borrelial lymphocytoma Specific IgG antibodies Histology; culture from skin biopsy Acrodermatitis chronica atrophicans High level of specific serum IgG antibodies Histology; culture from skin biopsy Early Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb Intrathecal total IgM and/or IgG synthesis; specific oligoclonal bands in CSF; seroconversion of specific serum IgG antibodiesa; culture from CSF Chronic Lyme neuroborreliosis Lymphocytic pleocytosis in CSF; intrathecally produced specific antibodiesb; specific serum IgG antibodies Specific oligoclonal bands in CSF Lyme arthritis High level of specific serum IgG antibodies Detection of borrelial DNA in synovial fluid and/or tissue (culture from synovial fluid and/or tissue) Lyme carditis Significant change in levels of specific IgG antibodiesa Culture from endomyocardial biopsy a Specific antibody levels in serum may increase in response to progression of infection or treatment, or may decrease due to abrogation of the infection process. Samples collected a minimum of 3 months apart may be required in order to detect a decrease in IgG levels. b Intrathecally produced specific antibodies are determined by investigating simultaneously drawn samples of CSF and serum. View Large Treatment and prevention Treatment It should again be noted that early manifestations of Lyme borreliosis, both localised and disseminated, eventually heal spontaneously without antibiotic treatment. The main reason to treat such patients is to shorten the duration of the manifestation and to prevent the development of later complications, especially LNB and Lyme arthritis; the latter occurred in more than 80% of untreated patients in the USA (Kalish et al.2001). In Europe, the chronic skin manifestation ACA may develop with all its complications (Asbrink, Hovmark and Olsson 1986; Asbrink et al.1986; Strle and Stanek 2009). Results of in vitro studies have shown that B. burgdorferi s.l. strains are susceptible to most penicillins, many second-generation and third-generation cephalosporins, tetracyclines and macrolides; they are resistant to specific fluoroquinolones, rifampicin and first-generation cephalosporins (Baradaran-Dilmaghani and Stanek 1996; Preac-Mursic et al.1996; Hunfeld et al.2005; Wormser et al.2006; Morgenstern et al.2009; Veinović et al.2013). Doxycycline, amoxicillin, phenoxymethylpenicillin and cefuroxime axetil are highly effective and are the preferred antimicrobial agents for the treatment of early localised manifestations. Macrolides such as azithromycin seem to be clinically somewhat less effective than other oral antibiotics and are consequently used as second-line treatment (Wormser et al.2006; Stanek et al.2012). Early disseminated disease such as LNB is usually treated with intravenous ceftriaxone or penicillin. However, results of more recent studies suggest that oral doxycycline treatment of LNB is as effective as intravenous ceftriaxone for the treatment of European adults with LNB (Borg et al.2005; Ljøstad et al.2008). The shortest duration of effective treatment has never been assessed for any of the antimicrobial agents listed above. Today, it is recommended that antibiotics should be administered for 2 weeks in cases of early localised and early disseminated disease. For chronic manifestations, a 4-week course is recommended. However, in early treatment studies patients suffering from Garin-Bujadoux-Bannwarth meningopolyneuritis were treated with intravenous penicillin G, 2 × 10 million units per day for 10 days, and in another study a similar cohort of patients was treated with intravenous ceftriaxone, 2 g per day, again for 10 days (Kristoferitsch et al.1987,1989). The outcome of treatment was compared with a cohort of well-documented Garin-Bujadoux-Bannwarth meningopolyneuritis patients who were not treated with antibiotics or with corticosteroids because they were seen before the spirochaetal aetiology of these disorders was discovered. Comparison of both groups revealed a significant improvement in patients whose treatment was started within 5 weeks after onset of the neurological disease (Kristoferitsch et al.1987,1989). That only 10 days of treatment is effective in early disease has been shown for doxycycline in a prospective (Wormser et al.2003) and a large retrospective clinical trial in the USA (Kowalski et al.2010). In a European study, the efficacies of 10 days and 15 days of oral doxycycline therapy were evaluated in adult patients with EM. A complete response was observed in 93% of the 15-day group and in 92% in the 10-day group. The frequency of non-specific symptoms in the patients was similar to that among controls. Thus, it was concluded that the 10-day regimen of oral doxycycline was not inferior to the 15-day regimen among adult European patients with solitary EM (Stupica et al.2012). Lyme arthritis typically responds to antibiotic treatment. Patients whose arthritis is improved but not resolved after an initial course of oral treatment can be re-treated with a second course of oral antibiotics, reserving parenteral antibiotic treatment for those without any substantial clinical response (Wormser et al.2006). Intra-articular steroids are not recommended before or during antibiotic treatment based on retrospective studies suggesting the potential for worse outcomes. Non-steroidal anti-inflammatory agents (NSAIDs) may be given with antibiotic therapy, and—since persistence of mild joint inflammation immediately following antibiotic therapy is found in about 25% of patients with Lyme arthritis—may also be required in several patients after antibiotic treatment. After resolution of arthritis of the knee, physical therapy may be needed if quadriceps atrophy has developed (Steere et al.2016). In patients not responding to NSAIDs, methotrexate or similar disease-modyfying antirheumatic drugs, given for 6–12 months, are usually effective. In patients with incomplete responses, arthroscopic synovectomy is an option (Avikar and Steere 2015; Steere et al.2016). Recommended antibiotic treatment for patients with Lyme borreliosis is shown in Table 2. Table 2. Recommended antibiotic treatment for patients with Lyme borreliosis; modified after Stanek et al. (2012). Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy od = once daily; bid = two times daily; tid = three times daily; qid = four times daily. i.v. = intravenous; IE = international units; a For children, total daily dosage is given, divided into the number of doses per day. b Age <8 years. c Azithromycin and erithromycin are used in patients allergic to penicillin and tetracyclines. d Ceftriaxone and penicillin G are used for treatment of erythema migrans and borrelial lymphocytoma very rarely (potentially for patients with severe immunodeficiency and for pregnant women). e Early Lyme neuroborreliosis is as a rule treated for 2 weeks, heart involvement for 2–3 weeks, late Lyme neuroborreliosis for 4 weeks. f For treatment of early Lyme neuroborreliosis, more information is available for 200 mg once daily than for 100 mg twice daily. g In case of recurrent Lyme arthritis or partial response to the initial treatment. h Ceftriaxone is most often used when there had been only a minimal response to previous oral antibiotics. View Large Table 2. Recommended antibiotic treatment for patients with Lyme borreliosis; modified after Stanek et al. (2012). Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy Dosing Clinical manifestation Antibiotic Mode of administration Adults Childrena Duration (days) Contraindications Erythema migrans, Borrelial lymphocytoma Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 10–14 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 14 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 14 Allergy Phenoxymethyl penicillin Oral 0.5–1.0 × 106 IE tid 0.1–0,15 × 106 IE/kg: 3 (maximum, 1 × 106 IE per dose) 14 Allergy Azithromycinc or Oral 500 mg bid, 20 mg/kg: 2 1st day Allergy 500 mg od 10 mg/kg 4 days or 500 mg od 10 mg/kg (maximum, 500 mg per day) 6 days Erithromycinc Oral 500 mg qid 28 mg/kg: 4 (maximum, 500 mg per dose) 14 Allergy Ceftriaxoned or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14 Allergy Penicillin Gd i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14 Allergy Lyme neuroborreliosis, Heart involvement Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28e Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 14–28e Allergy Doxycycline Oral 100 mg bid or 200 mg odf 4.4 mg/kg: 2 (maximum, 100 mg per dose) 14–28e Childrenb, pregnancy, lactation, allergy Lyme arthritis Initial treatment Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Retreatmentg Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 28 Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 28 Allergy Cefuroxime or Oral 500 mg bid 28–40 mg/kg: 2 (maximum, 500 mg per dose) 28 Allergy Ceftriaxoneh i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 14–28 Allergy Acrodermatitis chronica atrophicans Doxycycline or Oral 100 mg bid 4.4 mg/kg: 2 (maximum, 100 mg per dose) 21 (21–28) Childrenb, pregnancy, lactation, allergy Amoxicillin or Oral 500–1000 mg tid 25–50 mg/kg: 3 (maximum, 500 mg per dose) 21 (14–28) Allergy Ceftriaxone or i.v. 2 g od 50–100 mg/kg (maximum, 2 g per dose) 21 (14–28) Allergy Penicillin G i.v. 5 × 106 IE qid 0.25–0.5 × 106 IE/kg: 4 (maximum, 5 × 106 IE per dose) 21 (14–28) Allergy od = once daily; bid = two times daily; tid = three times daily; qid = four times daily. i.v. = intravenous; IE = international units; a For children, total daily dosage is given, divided into the number of doses per day. b Age <8 years. c Azithromycin and erithromycin are used in patients allergic to penicillin and tetracyclines. d Ceftriaxone and penicillin G are used for treatment of erythema migrans and borrelial lymphocytoma very rarely (potentially for patients with severe immunodeficiency and for pregnant women). e Early Lyme neuroborreliosis is as a rule treated for 2 weeks, heart involvement for 2–3 weeks, late Lyme neuroborreliosis for 4 weeks. f For treatment of early Lyme neuroborreliosis, more information is available for 200 mg once daily than for 100 mg twice daily. g In case of recurrent Lyme arthritis or partial response to the initial treatment. h Ceftriaxone is most often used when there had been only a minimal response to previous oral antibiotics. View Large Pregnant women with Lyme borreliosis receive the same antibiotic treatment as women who are not pregnant, except that doxycycline should be avoided. A congenital Lyme borreliosis syndrome is not reliably supported by any study (Maraspin et al.1996; Wormser et al.2006; Lakos and Solymosi 2010). According to rather limited data, the antibiotic treatment approach used for immunocompetent patients with EM is also effective in immunocompromised patients (Maraspin et al.1999b, Fürst et al.2006; Maraspin, Ruzic-Sabljic and Strle 2006), including those with underlying haematological malignancy (Maraspin et al.2015). Most probably the same is also valid for disseminated Lyme borreliosis such as LNB: immunocompromised patients (including those receiving biological therapy) can be effectively treated using the same antibiotics in equivalent dosages and duration as used for treatment of immunocompetent patients (Merkac, Tomazic and Strle 2015). Prevention The best way to avoid Lyme borreliosis is to avoid tick-infested areas, though this is not a realistic recommendation. A more practical measure is to wear protective clothing and/or use tick repellents on clothing and skin, particularly for those persons whose profession or passion requires periods in tick-infested areas. After exposure, inspection of the entire skin surface to remove any attached ticks is recommended because of the delay between the time of tick attachment and transmission of B. burgdorferi s.l. (see Fig. 3). Inspection of the scalp should be included and is particularly needed in small children who experience tick-bites on the scalp most frequently (Berglund et al.1995). A traditional recommendation is to remove the attached tick from the skin by grasping it with tweezers as close to the mouthparts as possible and then gently pulling it out. This recommendation, however, appears to be of little value when it comes to the tiny larvae or also I. scapularis nymphs that are smaller than Ixodes ricinus nymphs, and to parts of the body where it is difficult to make use of tweezers. Chemoprophylaxis with a single dose of 200 mg doxycycline after removal of an I. scapularis or an I. pacificus tick within 72 h was found beneficial in the USA (Nadelman et al.2001; Warshafsky et al.2010). In Europe, the principle of ‘watch and wait’ is recommended for I. ricinus tick bites because studies on the efficacy of antibiotic prophylaxis are limited (Schwameis et al.2017) and because overuse of antibiotics should be avoided. Further, the efficacy of antibiotic treatment of early localised and disseminated manifestations of Lyme borreliosis has been established (Stanek and Kahl 1999; Stanek et al.2012). Modification of the environment may reduce the density of tick populations around residences; for example, by the removal of leaf litter, the placing of wood chips where lawns are adjacent to forests, application of acaricides and the construction of fences to keep out deer (Stafford and Kitron 2002). According to American data, approaches to eradicate ticks and/or reservoir hosts have limited efficacy (Clark and Hu 2008); there are very few similar European information. Currently, no vaccine is available for prevention of Lyme borreliosis in humans; however, attempts to develop a vaccine continue (Barrett and Portsmouth 2013; Wressnigg et al.2013). Nevertheless, patients with Lyme borreliosis who are treated with appropriate antibiotics have an excellent prognosis. European Lyme borreliosis is a frequent disease with an increasing incidence in many countries. However, numerous scientifically questionable ideas on its clinical presentation, diagnosis and treatment may confuse physicians and lay people. The main messages of this predominantly clinical review on the European Lyme borreliosis are that a reliable diagnosis is a basis for a rational treatment, that for the diagnosis of Lyme borreliosis appropriate clinical signs should be present, that solid knowledge of clinical manifestations is essential for their recognition and that patients with Lyme borreliosis who are treated with appropriate antibiotics have an excellent prognosis. REFERENCES Aberer E , Bergmann AR , Derler AM et al. Course of Borr