An overview of bovine theileriosis

Abstract

Theileriosis is predominantly a disease of ruminants (domestic and wild) in tropical and subtropical countries of the world. Amongst several species infecting ruminants only few species are associated with severe clinical signs, notably T. parva and T. annulata in cattle and Theileria lestoquardi in sheep. Theileria parva is transmitted by Rhipicephalus appendiculatus and causes East Coast Fever (ECF) in susceptible cattle, while as T. annulata transmitted by different species of Hyalomma causes tropical theileriosis in cattle. The pathogenicity is mainly due to parasite development and multiplication in leukocytes. The infected host leucocytes are induced and activated by the schizonts, which associate with the mitotic spindle of the host cell during cell division. Theileria parasites are the only intracellular eukaryotic parasites capable of reversibly transforming host cells. The annual economic losses associated with ECF about USD 300 million and cattle loss in terms of mortality include approximately one million cattle per year. Tropical theileriosis also has serious economic impact in view of mortality, reduced milk yield, weight losses, abortions, and control costs associated with the disease, hence prevention is the best mean for effective and sustainable control.