Isolation and identification of Mycobacterium bovis in bovines with positive reaction to the tuberculin test in the state of Paraíba, northeast Brazil

Abstract

In areas where human tuberculosis and bovine tuberculosis coexist, differentiation between M. bovis and M. tuberculosis is important for monitoring the spread of M. bovis among cattle and from cattle to humans. The objective of this study was to isolate and identify M. bovis in bovines with positive diagnosis identified on tuberculin test in the State of Paraíba, Northeastern Brazil. Thirty-two bovines that tested positive in the comparative tuberculin test were used, from which samples of any organ with lesions suggestive of tuberculosis were collected, as well as lymph nodes, when no gross lesions were observed. Samples were submitted to histopathological exam, mycobacterial culture, Ziehl-Neelsen staining and molecular diagnosis. Twenty-one (65.6%) animals presented lesions suggestive of tuberculosis. As to body region 77.7% of lesions were found in the thoracic cavity, 12.4% in the head and 9.9% in the abdominal cavity. Among 55 samples submitted to mycobacterial culture, mycobacteria were isolated in 31 (56.4%), being 13 (41.9%) identified as M. bovis and 18 (58.1%) as Mycobacterium spp. Conclusion is that isolation and identification of M. bovis and Mycobacterium spp. in cattle suggests that humans are exposed to the risk of infection. This reinforces the need for intensification and optimization of prevention and control measures foreseen in the Brazilian National Program for the Control and Eradication of Bovine Brucellosis and Tuberculosis. Mycobacteria isolation and identification surveys are, therefore, encouraged in other Northeastern states.