Mycobacterium tuberculosis (M. tb) infection has been reported in over 60 Asian and African elephants under managed care, including elephants with known human contact in range countries.1,4,6 However, the risk of infection for free-ranging populations has been considered to be minimal. Wild Asian elephant (Elephas maximus) bulls that died with severe disease associated with M. tb have been recently discovered in national parks in India and Sri Lanka.2,7,10 In 2016, an African elephant bull (Loxodonta africana), estimated 45 years of age, was found dead near a tourist and staff camp in Kruger National Park, South Africa. Post-mortem examination revealed extensive pulmonary pathology, with an estimated 80% of the left lung and 40–50% of the right lung consisting of multifocal to coalescing encapsulated lesions, mixed with military focal gramulomas, which were consistent with mycobacterial infection. Serum extracted from heart blood had high levels of antibodies to the M. tb complex specific fusion antigen ESAT-6/CFP-10.3 Lung and lymph node tissues were processed for mycobacterial culture and Ziehl-Neelsen positive bacteria were speciated as M. tb.9 Whole-genome sequencing performed on extracted DNA confirmed that the isolate was unique from other elephant isolates, but clustered in the LAM3/F11 family commonly found in human TB patients in South Africa.5,8 These findings highlight the growing threat of human TB in wildlife globally, especially in countries with high human TB burdens, and the potential consequences of ignoring principles of One Health in addressing the reverse zoonosis that can lead to introduction of human pathogens into wildlife.
The authors would like to thank the following individuals for their contributions to this study: Guy Hausler, and the Veterinary Wildlife Services capture team from Kruger National Park for assistance with sample collection from this elephant. This work was supported by the South African Medical Research Council and the National Research Foundation of South Africa [SARChI grant 86949]. The content is the sole responsibility of the authors and does not necessarily represent the official views of the funders.
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