On the cultivation of Trypanosoma vivax: a tale of two visits in Nigeria.

A new method is presented for obtaining in vitro development of the insect cycle of Trypanosoma vivax. Bloodstream trypanosomes from infected sheep were inoculated to tsete fly organ cultures in a modified Eagle's medium with 20% sheep serum, and incubated at 28 C. The organisms multiplied first as elongate spiral trypomastigotes. In successful cultures these transformed to epimastigotes. The epimastigotes multiplied extensively to form dense layers attached to formed structures, especially to pieces of peritrophic membrane. In older cultures transitional forms appeared, including some approaching the morphology of metacyclic trypanosomes.