A comparison of susceptibility of two allopatric populations of Glossina pallidipes for stocks of Trypanosoma congolense.

A colony of Glossina pallidipes Austen which originated from Nguruman, Rift Valley Province, Kenya, was significantly more susceptible to infection (19.3%) with a stock of Trypanosoma congolense Broden isolated from G. pallidipes in Nguruman than a colony of the same species which originated from Shimba Hills, Coast Province, Kenya (5.6%). Male G.pallidipes from Nguruman were significantly more susceptible than females to this T.congolense stock whilst the susceptibility of both sexes of G.pallidipes from Shimba Hills did not differ significantly. All six goats on which six infected G.pallidipes fed singly (three tsetse per colony) became infected. Similarly, the G.pallidipes colony of Nguruman origin was significantly more susceptible to infection (16.4%) with a stock of T.congolense isolated from G.pallidipes in Shimba Hills than the colony of Shimba Hills origin (4.9%). The susceptibility of the sexes of G.pallidipes from both the colonies to this stock of T.congolense did not differ significantly. Again, all six goats on which six infected G.pallidipes fed singly (three tsetse per colony) became infected. If the observed differences in susceptibility of the two G.pallidipes colonies reflect transmission of trypanosomes by the two allopatric populations of tsetse in the field, then the epidemiology of congolense-trypanosomiasis in livestock must differ between these two areas of Kenya endemic for trypanosomiasis.