Studies on Glossina pallidipes, G. fuscipes fuscipes and G. brevipalpis in terms of the epidemiology and epizootiology of trypanosomiases in south-eastern Uganda.

Glossina pallidipes, G. f. fuscipes and G. brevipalpis in Stages I and II of hunger were caught from Bukunya and Buyundo villages in south-east Uganda during the period December 1969 to February 1971, and the origins of their blood meals identified. G. pallidipes fed mainly on bovids in the two villages; bushbuck was the most favoured host (44.9% of all blood feeds) though in Buyundo buffalo provided a significant alternative (20.8%). G. f. fuscipes frequently fed on bovids (75.6%), particularly bushbuck (46.7%), but it had a wider range of acceptable hosts. In both villages, G. brevipalpis took most of its blood meals from bushpig (45.5%), bovids (25.6%) and hippopotamus (28.5%). The feeding patterns of the three tsetse species during different months of the study period showed only small variations, and such differences were due probably to variations in the availability of the hosts. Examination of the relationships between trypanosome infection rates and natural hosts of the three vector species showed that the vivax-type infections originated from bovids, possibly bushbuck, while the congolense-type trypanosome came from bovids as well as bushpig. Hippopotamus probably had no trypanosome infections. There was a positive correlation between the trypanosome infection rates in the tsetse and the increasing mean maximum temperatures. In this region of Uganda, there was continuous transmission of pathogenic trypanosomes by the three tsetse species among their natural hosts; when present, the vectors' adventitious hosts became exposed to a high risk from the diseases. Man-fly contact during different months was impersonal, but high and sporadic. This is a high endemic region for human trypanosomiasis. Also, the introduced cattle succumb to the diseases very rapidly. The overall results are discussed in terms of the concept of challenge of African trypanosomiases.