A 48-year-old male developed fever and weakness 16 days after a safari in northwest Tanzania. Which organism is the most probable etiologic agent?

• A. Leishmania donovani
• B. Trypanosoma brucei
• C. Trypanosoma cruzi
• D. Brugia malayi

Answer: (B)

In this scenario the key idea is African trypanosomiasis caused by Trypanosoma brucei, transmitted by the tsetse fly in sub-Saharan Africa, including Tanzania. After a safari, exposure to tsetse flies can lead to infection that often begins with acute fever and malaise. The East African (rhodesiense) form tends to present more rapidly, within weeks, which fits the 16-day interval between exposure and symptoms. The geographic clue (northwest Tanzania) and the quick onset of fever after exposure strongly point to this parasite.

Leishmania donovani would cause visceral leishmaniasis with hepatosplenomegaly and a more chronic course. Trypanosoma cruzi is the agent of Chagas disease in the Americas, not Africa. Brugia malayi causes lymphatic filariasis with lymphedema and is not an acute febrile illness after a safari.