Biochemical, Molecular, Postmortem and Histopathological Characterization of Bovine Theilerioses at Different Stages of Production and Reproduction

Theilerosis is the most important common vector (Tick) born and hemoprotozoan diseases (TBDS) which pose a serious threat to the livestock population in terms of mortality, reduced milk yield and lowered draft power. The disease is having impact on biochemistry and systemic functions affecting at different stages of production and reproduction of dairy cattle as well as there is lack of accurate diagnosis of this disease. A total 1900 cases were suspected for theileriosis on the basis of clinical signs and total 950 cases were found positive for theileriosis on the basis of blood smear examination. As per the stages of pregnancy and lactation, the cases were classified as cows in early pregnancy, cows in late pregnancy, cows in post parturient stage, cows in early and late lactation period. Biochemical alterations like increased AST, ALT and BUN level indicating liver and kidney dysfunctions in all the groups and significantly higher in post parturient group. The serum phosphorus, calcium and magnesium level decreased in all the affected groups and mostly in late pregnancy period and post parturient stage indicating metabolic disturbances during the disease which were aggravated during theileriosis. Through molecular diagnosis 114 cows (65.51%) were found positive for T. annulata and 41 cows (22.9%) were found positive for T. orientalis and 19 cows (10.9%) were found positive for both Theileria annulata and Theileria orientalis. Phylogenetic analysis revealed the accession number for Theileria annulata was OQ230445 which is having 100% similarity with puri isolate and 98% similarity with Khorda isolate and the accession number for T. orientalis was OQ 230446 having 85% similarity with Khorda isolate. On necropsy, the animals were weak, debilitated with atrophy of the muscles. In some cases, the liver was enlarged, markedly congested and in some cases yellowish tinged surface and cut edges with distension of gall bladder was evident. Abomasal ulcers were distinct and considered as pathognomonic. On histopathological examination, the liver revealed necrosis of hepatocytes with sinusoidal congestion and infiltration of mononuclear cells. In lymphnode, there was depletion of lymphocytes in lymphoid follicles with congestion and haemorrhage. Pulmonary edema was also evident in few cases. The combined approach involving biochemical, molecular, Post-mortem and histopathological characters were found to be fruitful in diagnosis of the bovine theileriosis at different stages of production and reproduction with optimum specificity.