Evidence of Presence ofMycobacterium tuberculosisin Bovine Tissue Samples by Multiplex PCR: Possible Relevance to Reverse Zoonosis

Abstract

Bovine tuberculosis, caused by Mycobacterium bovis, remains one of the most important zoonotic health concerns worldwide. The transmission of Mycobacterium tuberculosis from humans to animals also occurs especially in countries where there is close interaction of humans with the animals. In the present study, thirty bovine lung tissue autopsy samples from an organized dairy farm located in North India were screened for the presence of Mycobacterium tuberculosis complex by smear microscopy, histopathological findings and PCR. Differential diagnosis of M. tuberculosis and M. bovis was made based on the deletion of mce-3 operon in M. bovis. The present study found eight of these samples positive for M. tuberculosis by multiplex PCR. Sequencing was performed on two PCR-positive representative samples and on annotation, and BLAST analysis confirmed the presence of gene fragment specific to Mycobacterium tuberculosis. The presence of M. tuberculosis in all the positive samples raises the possibility of human-to-cattle transmission and possible adaptation of this organism in bovine tissues. This study accentuates the importance of screening and differential diagnosis of Mycobacterium tuberculosis complex in humans and livestock for adopting effective TB control and eradication programmes.

The History of In Vivo Tuberculin Testing in Bovines: Tuberculosis, a “One Health” Issue

“…Where no effective eradication programme operates in cattle, the routine isolation of M. tuberculosis from multiple cattle raises the possibility of human-to-cattle-to-human transmission and the specter of increased zoonotic risk if M. tuberculosis strains adapt for bovines or other animals. Such findings underline the importance of adopting effective TB control and eradication programmes in humans and livestock alike ( 38 – 42 ). Indeed, the threat from zoonotic TB resulted in the adoption of a resolution by the OIE in 1983 which called for the eradication of M. bovis for both public health and economic reasons ( 43 ).…”

“…Indeed, the transmission of M. tuberculosis from human-to-animal-to-human still occurs, and is an ongoing risk, especially in countries where there is close interaction of humans with animals and, is of particular public health concern, in places such as zoos, circuses, and exotic animal facilities where there may be contact between TB-susceptible animals and humans ( 30 – 37 ). Where there is no effective eradication programme operational in cattle, the routine presence of M. tuberculosis in samples from multiple cattle raises the possibility of human-to-cattle-to-human transmission and possible adaptation of strains of M. tuberculosis in bovine or other animal tissues underlining the importance of adopting effective TB control and eradication programmes in humans and livestock alike ( 38 – 41 ).…”

Prevención y diagnóstico veterinario de la tuberculosis bovina. Una revisión de las tendencias globales

“…La principal desventaja de estos sistemas radica en que diagnostican falsos positivos con mucha facilidad debido principalmente a la contaminación de los reactivos en el proceso del laboratorio. Aun así, el diagnóstico de TBb mediante las variantes de PCR se ha convertido en una de las técnicas más rápidas, seguras y confiables [82][83][84].…”

Tuberculosis and One Health – What is in a Name?

“…Most animal isolates of M. tuberculosis originate from cattle, pigs, dogs, and Indian elephants, but the infection has also been demonstrated in captive and free-living wildlife. Molecular epidemiology has demonstrated transmission between humans and animals, in both directions ( 17 – 20 ). Other MTBC species, such as Mycobacterium microti , Mycobacterium pinnipedii , and Mycobacterium africanum , have also been isolated from various host species.…”