Studies on the epidemiology of trypanosomiasis in sheep and goats in Kenya.

The epidemiology of trypanosomiasis in a tsetse-infested range area of Kenya was studied for 2 years in various breeds of sheep and goats. Observations, including infection rates, PCV, temperature and weight loss indicated that the exotic breeds were more susceptible to natural trypanosomal infection than the indigenous breeds and that the infection may be severely debilitating and in many cases fatal. Observations of tsetse numbers and rainfall in the grazing area during the first year showed that there was a significant correlation between tsetse numbers and rainfall of the previous month. The increase in tsetse numbers, which occurred one month after substantial rainfall, was followed by an increase in the prevalence of trypanosomiasis in the animals. However, during the second year when rainfall was low there was no correlation between tsetse numbers and rainfall. It was concluded that the seasonal incidence of trypanosomiasis and the possible trypanotolerance of the indigenous breeds are important factors to be considered when initiating a small stock improvement programme for trypanosomiasis-endemic areas.