Human African trypanosomiasis (HAT), or sleeping sickness, is a parasitic infection that is endemic in sub-Saharan Africa and is almost invariably fatal unless treated.
The infection is transmitted to humans through the bite of an infected tsetse fly. The parasite multiplies in the lymph and blood, causing unspecific symptoms and signs (first-stage or haemolymphatic stage) and, over time, crosses the blood–brain barrier to infect the central nervous system (second-stage or meningo-ence