Trypanosoma varani and T. grayi-like trypanosomes : development in vitro and in insect hosts

The growth in vitro and the development in insect hosts of two reptilian trypanosomes was studied. The first was a Trypanosoma grayi-like isolate (Kiboko F4) from Glossina pallidipes in Kenya, East Africa, and the second was T. varani V54, isolated from Varanus exanthematicus in Senegal. T. varani V54 grew well in blood-agar culture media, but for successful long-term cultivation of the F4 trypanosomes, the presence of feeder cells from a triatomine or Xenopus cell line was essential. Experimental infection of tsetse (G. morsitans morsitans and G. palpalis gambiensis) and phlebotomine sandflies (Phlebotomus duboscqi) showed that T. grayi-like F4 trypanosomes, known and shown to develop in tsetse, did not multiply in the sandflies, whereas T. varani V54 grew well in the sandflies but not in the tsetse. It is concluded that these two reptilian trypanosome stocks probably represent different species, subject to confirmation from biochemical studies currently in progress. Attempts to isolate T. grayi sensu stricto from 13 wild African crocodiles in Zambia and Zaire were unsuccessful.