Another traveler's tale: African tick-bite fever

In the present report, we discuss the clinical and species-specific diagnosis of African tick-bite fever.

A 58-year-old man was admitted to the hospital for fever, headache, and myalgia. The clinical examination yielded only two small purpuric lesions with a dark center on the thigh and the abdomen. The patient reported that he had just returned from a 10-day trip to the eastern region of South Africa, and that he had hiked through the bush in Eswatini 7 days before the onset of fever. The white blood cell count showed lymphopenia, and the C reactive protein and alanine aminotransferase levels were mildly elevated. The diagnoses of bacteremia, malaria, COVID 19, and arboviruses were ruled out. Both the diagnoses of African tick-bite fever and Mediterranean spotted fever were plausible because both Rickettsia africae and Rickettsia conorii are present in South Africa. The presence of two skin lesions presumed to be necrotic eschars was a bit more suggestive of African tick-bite fever. Treatment with doxycycline was started once blood serology and a biopsy of the abdominal lesion had been performed. The outcome was rapidly favorable. A PCR assay performed on the abdominal eschar confirmed the involvement of R. africae, while the successive serological assays did not.

Numerous necrotic eschars without secondary maculopapular rash affecting the sole and palms are more commonly observed in African tick-bite fever than in Mediterranean spotted fever.