A Mild Form of East Coast Fever (Theileria Parva) With Persistence of Infection

Abstract

A parasite, isolated from some unknown wild animal, was transmitted through ten passages in high-grade cattle via Rhipicephalus appendiculatus and R. kochi. It proved to be a strain of Theileria parva of low virulence. Only 25 per cent of infected cattle died and the mortality rate was directly related to the number of ticks used to transmit the parasite. Some animals became carriers after recovery. It is suggested that the existence of such mild strains with persistent infectivity may account for some of the alleged successes of field treatments and possibly for sporadic cases of East Coast Fever that occur in areas with a long history of freedom from the disease.