East African trypanosomiasis — DTM&H MCQ

Correct answer: A — Early-stage East African trypanosomiasis

The correct answer is A, Early-stage East African trypanosomiasis. This traveller has the classic triad of rhodesiense sleeping sickness: a painful inoculation chancre at the tsetse bite site, fever with tachycardia within 10 days, and trypomastigotes on blood film. Trypanosoma brucei rhodesiense has a short incubation and progresses rapidly from the haemolymphatic (stage 1) to meningoencephalitic (stage 2) phase, so the absence of neurological signs and a normal CSF at day 10 confirms this is still stage 1 disease. Tanzania is a recognised rhodesiense focus, and safari-associated tsetse exposure with a bite-site chancre is the classic pattern seen in travellers returning to the UK. Why the other options are wrong: D. Acute Chagas disease: caused by Trypanosoma cruzi from triatomine bugs in the Americas, not East Africa; it produces a chagoma, not a tsetse-bite chancre, and is epidemiologically irrelevant to a Tanzanian safari. B. Visceral leishmaniasis: causes prolonged fever with hepatosplenomegaly over weeks to months, not an acute chancre, and diagnosis relies on amastigotes in tissue, not trypomastigotes on blood film. C. Relapsing vivax malaria: produces cyclical fever from intraerythrocytic parasites without a chancre; blood film would show ring/trophozoite forms, not extracellular trypomastigotes. E. West African trypanosomiasis with CNS disease: gambiense infection is chronic and indolent, with CNS involvement typically taking months to years to develop; a normal CSF at 10 days is incompatible with established CNS-stage disease. Key point: A painful chancre with rapid-onset fever within two weeks of East African safari exposure, trypomastigotes on blood film, and a normal CSF indicates early-stage T. b. rhodesiense infection, which advances to CNS disease far faster than the gambiense form.

Reference: PMC review: African Trypanosomiasis in Travelers Returning to the United Kingdom (Hospital for Tropical Diseases, London), describing safari-acquired T. b. rhodesiense with chancre and stage 1 vs stage 2 distinction; consistent with Manson's Tropical Diseases teaching. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2730280/