East Coast fever is a lethal disease of cattle, caused by a parasite that multiplies within T-lymphocytes, causing them to become lymphoblasts that behave like cells in leukaemia and lymphoma. This is the story of the disease and its effects on farmers, as well as of the scientists who studied it. 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 50 years. 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 had a negative effect on later investigators whose work was far more sound.