Trypanosomes

Specimen:

5 mL fresh blood in EDTA tube delivered immediately to the laboratory.

Method:

Microscopy of fresh wet smear or Giemsa-stained thick and thin blood films with, or without, the use of concentration methods.

Application:

Diagnosis of acute American trypanosomiasis (Chagas’ disease) caused by Trypanosoma cruzi;

diagnosis of African trypanosomiasis (sleeping sickness) caused by T. brucei gambiense; and

T. brucei rhodesiense.

Interpretation:

Identification of T. cruzi provides definitive diagnosis of American trypanosomiasis. 

A diagnosis of African trypanosomiasis is confirmed by the presence of T. brucei gambiense or T. brucei rhodesiense.

Repeated examinations may be necessary to demonstrate the presence of the organisms and, even using concentration techniques, false negatives may still occur.

Reference:

Garcia LS. Diagnostic Medical Parasitology. 4th ed. ASM Press 2001.

Bain NJ. Blood Cells. 3rd ed. Blackwell 2002.