Pathological and molecular detection of diseases of cattle at slaughter

Abstract

Background: This study was carried out to identify important zoonotic diseases of beef cattle at slaughter in Bangladesh. Methods: A total of 20 slaughtered cattle of both sexes, different ages and breeds were taken under investigation from Nilphamari, Rajshahi and Mymensingh district, Bangladesh during July to October, 2017. Detailed ante-mortem and post-slaughter lesions were inspected and the tissues from the lungs, liver, kidney and spleen were collected aseptically for histopathological examination. The tissue sections were processed and stained with hematoxylin and eosin (H&E) stain, acid fast stain and Gram stain. To detect the presence of specific microorganism in the tissues, the genomic DNA was extracted and polymerase chain reaction (PCR) was carried out. Results: Grossly, liver appeared as most affected organ followed by lungs, kidney and spleen. Wide spread necrosis and pipe steam liver due to fascioliasis (n=4), hydatidosis in lungs (n=3), congestion in the kidney (n=4) and petechial hemorrhage (n=2) in the spleen were the predominant lesions observed in the slaughtered cattle. H&E staining of tissue sections revealed granulomas in two liver and one lungs. Lung section stained with acid fast stain detected the acid fast bacilli in a case. Tissue sections stained with Gram stain showed cocci bacteria in the liver of two cattle. The PCR confirmed the presence of Mycobacterium tuberculosis in a cattle. Conclusions: Fascioliasis, hydatidosis and important zoonotic disease like tuberculosis are prevalent in the slaughtered cattle in Bangladesh. PCR technology appeared as a sensitive and specific screening test to diagnose tuberculosis. However, screening of large number of samples is necessary to detect the presence of important zoonotic diseases in cattle for safe beef production.