Pathological and molecular studies on tropical theileriosis in a HF cross cow calf

Bovine tropical theileriosis (BTT), a tick borne lymphoproliferative disease of bovines, is caused by intracellular hemopro-tozoan, Theileria annulata. It is one of the most economically significant disease of livestock in India. The blood sample from a month old HF cross cow calf with the history of high fever, anorexia and weakness was presented for hematological examination to Department of Veterinary Pathology, KNPCVS, Shirwal. The hematological analysis revealed anaemia as evident by decrease in Hb (6.5g/dl) and PCV (20.68%) values. The blood smear examination revealed piroplasms (annular rings/rods) of Theileria spp. in RBCs. The calf was died on same day and thorough necropsy was performed to note gross lesions. The carcass showed emaciation, pale/anaemic mucous membranes, swollen edematous prescapular lymphnodes, typical punched out ulcers in abo-masum, multifocal epicardial ecchymotic hemorrhages along with paleness in myocardial muscles were salient gross findings. The microscopic examination of impression smear from lymphnode revealed typical Koch blue bodies in lymphocytes. The histo-pathological examination of affected tissues corroborated with gross findings. DNA was extracted from the blood sample and PCR targetting Tams 1 gene specific for Theileria annulata yielded expected product of 751 base pair confirming the tropical theileriosis.