Abstract
Mycobacterium bovis (M. bovis) being the main cause of animal tuberculosis is a complex infectious agent and can be a cause of zoonotic tuberculosis zoonosis in public health. To date, the uncommon infection in public health due to M. bovis still is a great challenge to both veterinary and medical professions and requires a careful diagnosis and confirmation of the bacterium. Therefore, this study for the first time reports the clinical, gross, histopathological, and molecular based confirmation of M. bovis infection in wildlife animals (nilgai). Prior to death, the morbid animal showed severe pneumonic ailments like moist cough, thick nasal exudates, and dyspnoea. At necropsy, enlargement of mandibular cervical and mesenteric lymph nodes was observed. Different macroscopic lesions such as congestion and hyperaemia, creamy white and catarrhal exudates in trachea, consolidation, grey and red hepatisation of lungs, and micro- and macrogranulomatous tubercles containing caseous materials in lungs were observed. The heart of morbid animal showed congestions, myocarditis, and a copious amount of straw-colored fluid in the pericardial sac. At the microscopic level, lungs indicated granulomatous inflammatory response, presence of multinucleated giant cells, fibrosis, and punctuation of alveoli with chronic inflammatory cells. Histopathological examination of various sections of the heart of the infected animal showed chronic inflammatory response consisting of chronic inflammatory cells like monocyte, lymphocytes, and fibroblasts along with noncalcified eosinophilic materials. At the molecular level, M. bovis infection was confirmed in various tissues like the heart, lungs, cervical, and mesenteric lymph nodes in morbid animals. In conclusion, based on our results, it can be suggested that more molecular based epidemiological studies are crucial to know the exact cause of pulmonary and cervical tuberculosis in wild animals.