TROPICAL, TRAVEL AND EMERGING INFECTIONS (L CHEN AND A BOGGILD, SECTION
Update on Tick-Borne Bacterial Diseases in Travelers
Published online: 22 May 2018
Springer Science+Business Media, LLC, part of Springer Nature 2018
Purpose of Review Ticks are the second most important vectors of infectious diseases after mosquitoes worldwide. The growth of
international tourism including in rural and remote places increasingly exposes travelers to tick bite. Our aim was to review the
main tick-borne infectious diseases reported in travelers in the past 5 years.
Recent Findings In recent years, tick-borne bacterial diseases have emerged in travelers including spotted fever group (SFG)
rickettsioses, borrelioses, and diseases caused by bacteria of the Anaplasmataceae family.
Summary African tick-bite fever, due to Rickettsia africae, is the most frequent agent reported in travelers returned from Sub-
Saharan areas. Other SFG agents are increasingly reported in travelers, and clinicians should be aware of them. Lyme disease can
be misdiagnosed in Southern countries. Organisms causing tick-borne relapsing fever are neglected pathogens worldwide, and
reports in travelers have allowed the description of new species. Infections due to Anaplasmataceae bacteria are more rarely
described in travelers, but a new species of Neoehrlichia has recently been detected in a traveler. The treatment of these infections
relies on doxycycline, and travelers should be informed before the trip about prevention measures against tick bites.
Ticks are hematophagous arthropods considered the second
most common vector of human pathogens after mosquitoes
. Two families of ticks can transmit a wide range of patho-
gens: Ixodidae (hard ticks) and Argasidae (soft ticks). Ticks
from all regions carry specific pathogens that may remain
unknown to clinicians from other parts of the world. This is
an important issue when dealing with travel medicine.
International travel has continuously increased during the past
5 years, reaching a total of 1235 million international tourist
arrivals worldwide in 2016 . International tourism repre-
sents a significant source of income for developing countries,
and the trend is forecast to rise. Besides tourism, other reasons
for travel include business or studies, visiting friends and rel-
atives, and military or foreign aid development. In recent
years, international adventure tourism has also increased.
This type of tourism leads to potential human exploration into
previously untouched tick habitats, resulting in an increased
risk of tick bites and thus of tick-borne bacterial, viral, and
parasitic diseases. This review will focus on bacterial tick-
borne infections including rickettsioses, ehrlichioses, anaplas-
moses, and borrelioses .
Rickettsioses are obligate intracellular bacteria of the order
Rickettsiales. The taxonomy of these pathogens has been
widely reorganized in recent years due to the discovery of
many new species. Rickettsioses are associated with arthro-
pods mainly lice, ticks, mites, and fleas, which may act as
vectors or reservoirs of the bacteria. Most of spotted fever
group (SFG) are transmitted to the animal or human host
during the blood meal of hard ticks [3•].
The Anaplasmataceae family comprises Ehrlichia
chaffeensis, the agent of human monocytotropic ehrlichiosis
(HME) transmitted by Amblyomma ticks, Anaplasma
phagocytophilum, the agent of human granulocytic anaplas-
mosis (HGA), transmitted by Ixodes ticks, and “Candidatus
Neoehrlichia mikurensis,” the agent of Neoehrlichioses in
This article is part of the Topical Collection on Tropical, Travel and
* Carole Eldin
Aix Marseille University, IRD, AP-HM, SSA, Vecteurs-Infections
Tropicales et Méditerranéennes (VITROME), IHU-Méditerranée
Infection, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
Current Infectious Disease Reports (2018) 20: 17