A	B

A, B: Two areas from a blood smear from a patient with African trypanosomiasis.  Thin blood smear stained with Giemsa.  Typical trypomastigote stages (the only stages found in patients), with a posterior kinetoplast, a centrally located nucleus, an undulating membrane, and an anterior flagellum.  The two T. brucei species that cause human trypanosomiasis, T. b. gambiense and T. b. rhodesiense, are indistinguishable morphologically.  The trypanosomes length range is 14 to 33 µm.

C

D

C, D: Blood smear from a patient with T. b. rhodesiense, Giemsa stain.  D shows the same field as C, with the addition of differential interference contrast (DIC) which better visualizes the flagella (DIC is not necessary for diagnosis!).  41-year-old man who had returned from a trip to Tanzania.  Specimen contributed by Dr. Phil Smith, Omaha, Nebraska.

E

E: Blood smear from a patient (a U.S. traveler) with T. b. rhodesiense.  A dividing parasite is seen at the right.  Dividing forms are seen in African trypanosomiasis, but not in American trypanosomiasis (Chagas disease).

F

F: Blood smear from a patient with T. b. gambiense.  Image contributed by Prof. J. Le Bras, Hôpital Bichat - Claude Bernard, Paris, France.