Infection by Theileria parasites limits the movement of cattle between countries and can result in production losses and high mortality in susceptible animals. Because these diseases are most severe in recently introduced animals, they are a constraint on the importation of new breeds or improved stock. The two diseases with the greatest economic impact in cattle are East Coast fever (infection with Theileria parva) and tropical theileriosis (infection with Theileria annulata). Theileria lestoquardi, which causes a severe disease with a high morbidity and mortality rate, is the most important species in sheep and goats.
Iowa State University
Iowa State University Center for Food Security and Public Health, "Theileriosis" (2009). Center for Food Security and Public Health Technical Factsheets. 132.