African Tick Bite Fever in Travelers to Rural Sub-Equatorial Africa

Jensenius, Mogens
Fournier, Pierre-Edouard
Vene, Sirkka
Hoel, Terje
Hasle, Gunnar
Henriksen, Arne Z.
Hellum, Kjell Block
Raoult, Didier
Myrvang, Bjørn

¹Department of Internal Medicine, Aker University Hospital, Oslo
²Department of Preventive Medicine, Oslo
³Department of Infectious Diseases, Ullevål University Hospital, Oslo
⁴Oslo Travel Clinic, Oslo
⁵Department of Infectious Diseases, St. Olav's University Hospital, Trondheim
⁶Department of Infectious Diseases, Akershus University Hospital, Nordbyhagen, Norway
⁷Swedish Institute for Infectious Disease Control, Solna, Sweden
⁸Unité des Rickettsies, CNRS, UMR 6020 Université de la Mediterranee, Marseille, France

Reprints or correspondence: Dr. Mogens Jensenius, Div. of Infectious Diseases, Dept. of Internal Medicine, Aker University Hospital, N-0514 Oslo, Norway ([email protected]).

Received 18 December 2002; revised 15 May 2002; accepted 6 February 2003.

Financial support: Norwegian Research Council (grant 136239/320); Research Forum, Aker University Hospital; Centre for Tropical and Imported Diseases, Ullevål University Hospital, Oslo, Norway.

Members of the study group are listed at the end of the text.

Clinical Infectious Diseases 36(11):p 1411-1417, June 1, 2003. | DOI: 10.1086/375083

To estimate the incidence of, identify risk factors for, and describe the clinical presentation of travel-associated African tick bite fever (ATBF), a rapidly emerging disease in travel medicine, we prospectively studied a cohort of 940 travelers to rural sub-Equatorial Africa. Diagnosis was based on suicide polymerase chain reaction and the detection of specific antibodies to Rickettia africae in serum samples by multiple-antigen microimmunofluorescence assay, Western blotting, and cross-adsorption assays. Thirty-eight travelers, 4.0% of the cohort and 26.6% of those reporting flulike symptoms, had ATBF diagnosed. More than 80% of the patients had fever, headache, and/or myalgia, whereas specific clinical features such as inoculation eschars, lymphadenitis, cutaneous rash, and aphthous stomatitis were seen in ≤50% of patients. Game hunting, travel to southern Africa, and travel during November through April were found to be independent risk factors. Our study suggests that ATBF is not uncommon in travelers to rural sub-Saharan Africa and that many cases have a nonspecific presentation.