East Coast fever is a lethal disease of cattle caused by a parasite. It affects and distorts lymph cells and causes them to behave like cells in leukemia and lymphoma. The disease was unknown to Western science or to veterinary practice until it was introduced into Rhodesia in 1901. It devastated the cattle-raising and ox-cart dependent transport systems of Rhodesia and South Africa and was not fully brought under control for some fifty years. It remains a serious problem in East and Central Africa. The book describes the social and economic impact of the outbreak, the scientific investigations into it, and the effort to control it. The scientific study of the disease was done in part by the famous bacteriologist, Robert Koch, whose many early errors retarded later investigations, which were far more sound. Much of the text is accessible to the nonspecialist reader and one chapter deals with the present-day understanding of the basic nature of the disease.