Trypanosoma brucei

a salivarian species widely distributed in Africa where it is transmitted by the bites of tsetse flies from a reservoir in wild animals to domestic animals, especially cattle, in which it causes nagana. Some systems of classification divide this species into three subspecies, although they are morphologically indistinguishable: T. brucei brucei, which causes nagana; T. brucei gambiense, which causes West African trypanosomiasis; and T. brucei rhodesiense, which causes East African trypanosomiasis. Other authorities prefer to grant species status to T. gambiense and T. rhodesiense because of their biologic and epidemiologic differences.