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[Trypanosoma brucei gambiense] [Trypanosoma brucei rhodesiense]

The two Trypanosoma brucei species that cause African trypanosomiasis, T. b. gambiense and T. b. rhodesiense, are indistinguishable morphologically.  A typical trypomastigote has a small kinetoplast located at the posterior end, a centrally located nucleus, an undulating membrane, and a flagellum running along the undulating membrane, leaving the body at the anterior end.  Trypomastigotes are the only stage found in patients.  Trypanosomes range in length from 14 to 33 µm.

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A: Trypanosoma brucei sp. in a thin blood smear stained with Giemsa.  The trypomastigote is beginning to divide; dividing forms are seen in African trypanosomes, but not in American trypanosomes.