Changes in the distribution of cattle and of bovine trypanosomiasis associated with the spread of tsetse-flies (Glossina) in southwest Uganda.
Abstract
The following is based partly on the authors' summary. Glossina morsitans morsitans Westw. entered Ankole in south-western Uganda in 1907. Its northward spread in the region west of Lake Victoria has been under observation since 1914 [cf. RAE B 17 120; 49 283]. Apart from one recession after a rinderpest epizootic in 1919-20, the spread was continuous, the area occupied increasing by 20-300 mile2 per annum, until 1960 when it was halted by the use of insecticides and the control of wild animals [cf. 54 168]. An existing infestation of G. pattidipes Aust., G. fuscipleuris Aust. and perhaps G. fuscipes fuscipes Newst. in north-western Ankole expanded during the same period. The paper is principally concerned with the regrowth of the Ankole cattle population after the catastrophic mortality of the 1890-91 panzootic, and the 1919-20 local epizootic of rinderpest. This recovery took place in the continuously narrowing corridor between the two fly belts. It was observed that infection by Theileria parva exerted a greater direct control over the rate of growth of the Ankole cattle population than did trypanosomiasis and that the principal effect of the latter was to limit the area available for grazing. Trypanosoma congolense was relatively more common in heavily infected cattle near the fly-belts. As the incidence of infection declined in cattle further away from the fly-belts, T. vivax became the dominant trypanosome.