Human African trypanosomiasis.

Human African trypanosomiasis (sleeping sickness) is caused by the unicellular parasite Trypanosoma brucei and transmitted by tsetse flies. It occurs exclusively in sub-Saharan Africa, usually in rural areas affected by civil conflicts and neglected health systems. Reported cases are fewer than 10,000/year, which classifies it as one of the most neglected tropical diseases. Because sleeping sickness is fatal if not treated, it has to be included in the differential diagnosis of every febrile traveler returning from a game park in East Africa. Elimination of the disease is considered feasible provided better tools for diagnosis and treatment can be made available.