African tick-bite fever — DTM&H MCQ

Correct answer: D — Doxycycline

The correct answer is D, doxycycline, because this vignette describes African tick bite fever (Rickettsia africae), the classic cause of a returning safari illness with fever, headache, and multiple inoculation eschars affecting several members of a group. Doxycycline is the treatment of choice for rickettsial infections, acting on the intracellular pathogen and producing rapid defervescence, typically within 24 to 48 hours of starting therapy. The clustering of illness in companions reflects the fact that Amblyomma ticks that transmit Rickettsia africae aggressively attack multiple people simultaneously during bush walks or game drives, and unlike most other spotted fever rickettsioses, multiple eschars are considered near pathognomonic for this diagnosis. UK travel medicine and dermatology practice both support a short course of doxycycline, often around 100 mg twice daily for 5 to 14 days depending on severity, as first line. Why the other options are wrong: E. Chloroquine: this is an antimalarial with no activity against rickettsial organisms, and malaria does not cause eschars. B. Praziquantel: this is an anthelminthic used for schistosomiasis and other flukes, irrelevant to a bacterial tick borne illness with eschars. C. Metronidazole: this targets anaerobic bacteria and protozoa such as amoebiasis or giardiasis, and has no useful activity against Rickettsia species. A. Ciprofloxacin: fluoroquinolones have unreliable and inferior activity against rickettsiae compared with tetracyclines, and are not recommended first line treatment for spotted fever group rickettsioses. Key point: fever plus multiple eschars in a cluster of safari travellers points to African tick bite fever, which is treated with doxycycline.

Reference: British Journal of Dermatology, GD09 Spotted fever after safari: a case of African tick bite fever highlighting the value of eschar swabs for the molecular detection of rickettsial disease, 2025, https://academic.oup.com/bjd/article/193/Supplement_1/ljaf085.461/8161991