Clinico-pathological and haemato-biochemical alterations in fatal bovine tropical theileriosis diagnosed by nested PCR

This investigation was designed to characterize the clinico-pathological and haemato-biochemical profile in naturally acquired, fatal cases of cattle theileriosis, a tick-transmitted haemoprotozoan infection of considerable veterinary and economic concern attributed to Theileria annulata. Three crossbred cattle admitted in the terminal stage of disease were evaluated at the Teaching Veterinary Clinical Complex of Guru Angad Dev Veterinary and Animal Sciences University (GADVASU), Ludhiana. The identity of the pathogen was first established by conventional Giemsa-stained microscopy and confirmed by nested PCR targeting the Tams1gene, with previously confirmed T. annulata-positive DNA and nuclease-free water serving as positive and negative controls, respectively. Post-mortem gross inspection disclosed pronounced splenomegaly, lymphadenomegaly, and characteristic punched-out ulcerative lesions of the abomasal mucosa. Histopathological examination demonstrated mucosal necrosis of the abomasum with lymphomononuclear infiltration of the submucosa, degenerative alterations in myocardial fibers with associated inflammatory infiltrates, interstitial pneumonic changes with pulmonary emphysema, notable lymphoid hyperplasia of the spleen, and intracellular schizonts (Koch’s blue bodies) within lymph node mononuclear cells. These tissue-level changes occurred in parallel with haemato-biochemical disturbances, including derangements in total white blood cell count, erythrocyte count, haemoglobin percentage, packed cell volume, and differential neutrophil percentage, along with significantly elevated serum levels of alkaline phosphatase (ALP), aspartate aminotransferase (AST), blood urea nitrogen (BUN), total bilirubin, uric acid, iron, and total protein. The observed abnormalities are attributable to systemic dissemination of schizont-infected mononuclear cells and the resulting host immunopathological response.