Studies on Trypanosoma (nannomonas) congolense II. Observations on the cyclical transmission of three field isolates by Glossina morsitans morsitans.

Teneral flies of Glossina morsitans morsitans were fed on mice infected with cloned and uncloned derivatives of three recent field isolates of Trypanosoma (Nannomonas) congolense. Flies with mature infections were identified by the warm-slide probe method and phase-contrast microscopy. High infection rates were achieved when such flies were fed on mice at peak parasitaemia. The infection rates were low when flies were fed on mice prior to or late after peak parasitaemia. The duration of the developmental cycle of T. congolense in the tsetse fly varied from 7 to 40 days: in 45% of the infective flies the developmental cycle was completed within 12 days; and in 76%, within 18 days.