histopathological changes of real time- pcr detection for mycobacterium bovis of cattle in iraq

Bovine tuberculosis caused by mycobacterium bovis remains a significant disease of cattle and other species in many countries. the aim of this study is to describe the gross pathology and macroscopic features of tuberculosis in bovine slaughtered in al-muthanna abattoir in molecular analysis to detect bacteria supported by histopathological analysis of granulomas. twenty-five cattle and buffaloes of different ages showing gross signs of tb were studied. collection samples from lung, liver, and lymph node and preserve it in 10% neutral buffered formalin. the quantative pcr and histopathological examination were done for samples from october 2023 to april 2024. fifty samples (25 cattle and 25 buffalo) were analyzed. gross examination revealed white to whitish-yellow, firm, protruding nodules, primarily in the upper and lower lung lobes, containing caseous necrotic material. molecular analysis using qpcr targeting the tb gene detected m. bovis in 6 samples (12%), with a higher prevalence in cattle (20%) compared to buffalo (4%). histopathological examination confirmed granulomas in positive samples, characterized by central necrosis surrounded by neutrophils, macrophages, lymphocytes, plasma cells, epithelioid cells, and langhan’s giant cells. pulmonary lesions were graded into early and late stages based on necrosis, mineralization, and immune cell infiltration (primary tuberculosis) .lymph nodes exhibited granulomatous nodules with caseous necrosis, while liver samples showed solid granulomas with inflammatory cell infiltration (secondery tuberculosis). these findings underscore the utility of molecular diagnostics and histopathology in detecting and understanding m. bovis infection.