Shedding Of Mycobacterium Bovis In Respiratory Secretions Of Free-Ranging Wild Dogs (Lycaon Pictus): Implications For Intraspecies Transmission

It has recently been discovered that Mycobacterium bovis (M. bovis) causes disease in the endangered African wild dog (Lycaon pictus) in areas endemic for bovine tuberculosis (bTB), including the Kruger National Park (KNP). However, information on M. bovis infection dynamics within this species is limited and requires investigation as M. bovis can cause conservation consequences due to movement restrictions, crucial for genetic management. This study had two aims: to investigate mycobacterial shedding in free-ranging wild dogs from KNP by culturing oropharyngeal swab (OS) and bronchoalveolar lavage (BAL) samples; and to determine the test association between ante-mortem culture and interferon gamma release assay (IGRA) results as well as agreement between OS culture and BAL culture results. Mycobacterial culture revealed that 6 of 173 (3.5%) OS samples and 1 of 32 (3.1%) BAL samples were M. bovis culture positive, suggesting that wild dogs can shed M. bovis through respiratory secretions. However, the possibility of contamination by ingestion of infected prey cannot be excluded in wild dogs with positive OS culture results. Furthermore, the test outcomes between IGRA and culture (OS and BAL) differed substantially, with 134 out of 172 wild dogs having IGRA-positive results (detectable M. bovis immune sensitization), whereas only 7 out of 173 wild dogs had culture-positive results. These findings suggest that intraspecies transmission of M. bovis may be possible among wild dogs. Although the risk of intraspecies transmission is currently unknown, this knowledge is important for assessing the risk of M. bovis transmission from infected wild dogs to uninfected populations during translocations.