The role of game animals in the maintenance of endemic and enzootic trypanosomiases in the Lambwe Valley, South Nyanza District, Kenya

Abstract

Rhodesian sleeping sickness and bovine trypanosomiasis were endemic in the Lambwe Valley of western Kenya, where the vector of both diseases was a tsetse fly Glossina pallidipes. Since a large resident population of game animals also inhabited the valley, a programme was designed to assess the relationships between game animals, tsetse, and trypanosome populations and the results were collated with some aspects of local human ecology and the general epidemiological situation in the valley. Of 134 game animals examined for trypanosome infections, 16.4% were found to be positive. This overall infection rate was similar to that found in cattle in the same area. T. brucei was the commonest trypanosome found in game animals, but the isolation of T. rhodesiense from a reedbuck (Redunca redunca) was of greater interest. Altogether, 90% of the bushbuck (Tragelaphus scriptus) examined were infected with animal trypanosomes; this is particularly significant since bushbuck was the preferred host of G. pallidipes and greatly influenced the distribution pattern and behaviour of the tsetse. It was concluded that the association existing between bushbuck and G. pallidipes was extremely important in creating disease foci and that the spread of infections to man was largely a result of poaching activities.