The major constraint to livestock development in Africa is tsetse-transmitted trypanosomiasis. Direct and indirect losses due to trypanosomiasis have been estimated to be many billions of dollars annually, and the situation appears to be deteriorating, with major tsetse advances occurring throughout the continent. Currently, efforts to control tsetse are limited by the high cost and complex logistics required; no field vaccine is available; and the increased use of trypanotolerant livestock is limited by the fact that only small numbers are available. Thus, African producers must lean heavily on the trypanocidal drugs available and must learn to use them more effectively if any significant improvements into the control of trypanosomiasis are to be made in the immediate future.
Published reports on livestock productivity under chemoprophylaxis are few in number, deal only with very small samples of animals, and usually evaluate only growth and mortality as indicators of performance. It has, however, been noted that the Mkwaja Ranch in Tanzania has over many years built up a collection of records on animal productivity and disease, probably unique in Africa.
In early 1982, discussions were held at Mkwaja between representatives of May and Baker Ltd., the International Livestock Centre for Africa (ILCA), the International Laboratory for Research on Animal Diseases (ILRAD), and staff of Amboni Ltd. It was concluded that a major, well designed study of matching productivity and health data, linked with earlier ecological and tsetse control work, would be of outstanding value. Such a study would provide the, opportunity to evaluate, on a much larger scale than ever before, the effectiveness of the use of Samorin (isometamidium chloride) as a chemoprophylactic on East African cattle exposed to a severe tsetse challenge.
