The alpha-gal allergy is an emerging IgE-mediated reaction against the galactose-alpha-1,3-galactose carbohydrate found in mammalian meats. Patients with this condition will develop anaphylactic symptoms 3–6 h after the ingestion of mammalian meat food products such as beef, pork or lamb. The prevalence of this allergy is drastically increasing and severe reactions including anaphylactic shock have been reported, yet many patients experience symptoms for years before a diagnosis is made. We describe the presentation, diagnosis and management of a patient with the alpha-gal allergy in attempt to improve early recognition and management of patients with this condition. INTRODUCTION CASE REPORT The alpha-gal allergy is a recently recognized IgE-mediated A 60-year-old Caucasian male presented to his primary care reaction against the galactose-alpha-1,3-galactose carbohy- physician (PCP) with a 3-week history of daily spontaneous drate found in non-primate mammalian meats . Unlike other allergic reactions without an identiﬁable cause or pattern. His food allergies, this condition elicits a delayed onset of anaphyl- symptoms included a painful and pruritic urticarial rash actic symptoms 3–6 h after the ingestion of mammalian meat involving his entire body along with abdominal pain, diarrhea, food products such as beef, pork or lamb. Studies suggest that congestion, cough and sore throat. The patient reported mul- being bitten by the lone star tick (Amblyomma americanum)is tiple episodes of waking in the middle of the night with severe the only signiﬁcant cause of these responses in the United pruritus that would resolve a few hours after taking Benadryl. States . These ticks are common in the southeastern region One reaction led to shortness of breath and constriction of the of the country. Although the prevalence of the alpha-gal allergy patient’s throat, so he went to the emergency department and is drastically increasing and severe reactions leading to ana- was treated for anaphylaxis (Fig. 1). phylactic shock can occur , this condition is rarely recognized The patient’s medical history was unremarkable with no and a mean time of 7.1 years to diagnosis was found in 2017 . previous diagnoses of allergies, asthma or atopy. No speciﬁc Delayed diagnosis of an allergy that has proven to elicit such triggers for these reactions could be identiﬁed, and the patient potent reactions is exceptionally dangerous. reported no changes in soaps, washing detergents or stress We report a 60-year-old male with alpha-gal allergy in levels. He denied consuming alcohol, but did report a diet rich attempt to improve early recognition and management of in beef and dairy products. The patient also acquired a tick bite patients with this condition. in Arkansas ~2 weeks prior to the onset of symptoms. Received: October 19, 2017. Revised: November 14, 2017. Accepted: November 22, 2017 © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact firstname.lastname@example.org Downloaded from https://academic.oup.com/omcr/article-abstract/2018/2/omx098/4897468 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Mammalian meat allergy following a tick bite 59 meat products. He continues to tolerate ﬁsh, turkey and chicken with no further reactions or symptoms as long as mammalian meat products are avoided. DISCUSSION The prevalence of the alpha-gal allergy is drastically increasing and although not all patients sensitive to alpha-gal will experi- ence symptoms, an estimated 10% of some populations in the United States may have increased IgE titers against the alpha- gal carbohydrate . This allergy has proven its ability to elicit powerful and potentially lethal reactions including anaphyl- actic shock, yet it is commonly misdiagnosed or determined to be idiopathic in origin. A recent study reports that only 21% of patients are diagnosed within a year of experiencing symptoms and a mean time to diagnosis of 7.1 years . The ﬁrst case of alpha-gal allergy was reported less than a decade ago and very few publications that discuss its clinical presentation and diagnosis are available, making this condition difﬁcult to recognize. The delayed onset of symptoms makes it challenging for patients and their healthcare providers to iden- tify a causal antigen, and meats are often overlooked as a poten- tial cause of the reactions because the alpha-gal allergy is the only known hypersensitivity against mammalian meat products. Figure 1: Urticarial rash involving the patient’s trunk. Patients with undiagnosed alpha-gal allergy typically pre- sent to their PCP or allergist complaining of recurrent anaphyl- actic symptoms that include an urticarial rash, angioedema, diarrhea, vomiting or respiratory issues. Primary presentation to the emergency department due to severe anaphylaxis is also common. Alpha-gal allergy is diagnosed by measuring serum IgE-antibody titers against the galactose-alpha-1,3-galactose carbohydrate or against speciﬁc mammalian meats such as beef, pork or lamb. Titers above 0.35 kU/L are considered to be elevated. Although most anaphylactic reactions occur after eating mammalian meat, any food product that contains the alpha- gal carbohydrate may elicit a response. Some patients includ- ing the individual in this report will experience reactions to gelatin, milk, whipping cream and cheese as these foods con- tain alpha-gal . This carbohydrate is also found on cetuxi- mab, a chimeric mouse-human IgG monoclonal antibody drug used to treat cancers, asthma, inﬂammatory bowel disease and rheumatoid arthritis. Patients with alpha-gal allergy can develop severe anaphylactic reactions when taking this drug . Abstinence from mammalian meat products is currently the only method for preventing alpha-gal allergy symptoms, but Figure 2: Urticarial lesion located on patient’s axilla. some patients do report a regression of symptoms over time. Individuals with this allergy should be prescribed an epineph- An urticarial rash involving the torso, upper extremity and rine autoinjector (EpiPen) for acute reactions, and some patients dorsum of the hand was noted upon examination. The urticarial may require further treatment with antihistamines as the com- lesions were annular, slightly raised, various in size and blanch- plete avoidance of mammalian meat products can be difﬁcult. ing. The patient reported the rash would last <24 h (Fig. 2). Patients diagnosed with alpha-gal allergy in the primary care Differential diagnoses for this patient included tick-borne setting should be referred to an allergist for management. illnesses, chronic idiopathic urticaria, mast cell activation This case is highlighted to improve awareness of the increas- syndrome (MCAS) and alpha-gal allergy. Laboratory testing ingly prevalent alpha-gal allergy, especially in the primary indicated a signiﬁcant elevation of IgE titers against galactose- care setting. Patients complaining of recurrent anaphylaxis alpha-1,3-galactose at 8.45 kU/L (normal <0.35). A complete should be tested for alpha-gal allergy since it can elicit such blood count and comprehensive metabolic panel ruled out any potent reactions. Future studies should include investigation metabolic triggers and serum tryptase testing ruled out MCAS. of the mechanisms behind the delayed hypersensitivity seen Antibody titers against tick-borne illnesses such as Rocky in alpha-gal allergy. Determining what factors cause some Mountain spotted fever were within normal limits, and the patients to experience a decline in symptoms is another topic diagnosis of alpha-gal allergy was made. for analysis. A comprehensive analysis of the true incidence of The patient was prescribed an epinephrine autoinjector this condition could also help to further illuminate the impact (EpiPen), hydroxyzine, and was advised to avoid mammalian of alpha-gal allergy. Downloaded from https://academic.oup.com/omcr/article-abstract/2018/2/omx098/4897468 by Ed 'DeepDyve' Gillespie user on 16 March 2018 60 W.L. Jackson ACKNOWLEDGMENTS REFERENCES This work was mentored by the NYITCOM at A-State faculty 1. Steinke JW, Platts-Mills TA, Commins SP. The alpha-gal and research ofﬁce. story: lessons learned from connecting the dots. J Allergy Clin Immunol 2015;135:589–96. DOI:10.1016/j.jaci.2014.12. CONFLICT OF INTEREST STATEMENT 2. Wolver SE, Sun DR, Commins SP, Schwartz LB. A peculiar No conﬂicts of interest. cause of anaphylaxis: no more steak? The journey to discov- ery of a newly recognized allergy to galactose-alpha-1, FUNDING 3-galactose found in mammalian meat. J Gen Intern Med 2013; 28:322–5. DOI:10.1007/s11606-012-2144-z. This work was supported by the New York Institute of Technology 3. Flaherty MG, Kaplan SJ, Jerath MR. Diagnosis of life-threatening College of Osteopathic Medicine at Arkansas State University alpha-gal food allergy appears to be patient driven. J Prim Care research ofﬁce. Community Health 2017. DOI:10.1177/2150131917705714. 4. Commins SP, Satinover SM, Hosen J, Mozena J, Borish L, ETHICAL APPROVAL Lewis BD, et al. Delayed anaphylaxis, angioedema, or urti- All ethical requirements have been fulﬁlled for this publication. caria after consumption of red meat in patients with IgE antibodies speciﬁc for galactose-alpha-1,3-galactose. J Allergy Clin Immunol 2009;123:426–33. DOI:10.1016/j.jaci.2008.10.052. CONSENT 5. Mullins RJ, James H, Platts-Mills TA, Commins S. Relation- Written informed consent for publication of this article and any ship between red meat allergy and sensitization to gelatin accompanying images was obtained from the patient. and galactose-α-1, 3-galactose. J Allergy Clin Immun 2012;129: 1334–42. GUARANTOR 6. Chung CH, Mirakhur B, Chan E, Le QT, Berlin J, Morse M, et al. W. Landon Jackson, New York Institute of Technology College of Cetuximab-induced anaphylaxis and IgE speciﬁc for Osteopathic Medicine at Arkansas State University, Jonesboro, galactose-a-1,3-galactose. N Engl J Med 2008;358:1109–17. AR 72401. DOI:10.1056/NEJMoa074943. Downloaded from https://academic.oup.com/omcr/article-abstract/2018/2/omx098/4897468 by Ed 'DeepDyve' Gillespie user on 16 March 2018
Oxford Medical Case Reports – Oxford University Press
Published: Feb 1, 2018
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