The largest study of free-ranging rhinos in the Kruger National Park revealed that one in seven rhinos was infected with Mycobacterium bovis (M. bovis), the pathogen that causes bovine tuberculosis.
A study by Stellenbosch University’s Animal Tuberculosis Research Group sampled 437 rhinos between 2016 and 2020 and found M. Bovis in 15.4 % of the park’s rhino population.
Most of the infected rhinos are asymptomatic. ‘It can be compared to humans who are infected with Covid-19 or have latent TB but are asymptomatic. The infected rhinos are harbouring the bacteria, but their immune system is keeping it in check,’ says Professor Micheal Miller, the South African research Chair in animal TB at the National Research Foundation.
‘They are not losing weight or coughing, and if you looked at a group of 400 rhinos, you wouldn’t be able to pick out those that are infected. They can potentially live for years with infection if it is contained.’
The authors of the study said the results were not surprising, considering that TB is prevalent in at least 15 other species in the park.
Significantly, a cluster of cases was detected near the Kruger’s south-western border. The area surrounding this border consists primarily of farmland. Herds of livestock historically have been implicated in the spill over of M. bovis to wildlife in the park, particularly in buffaloes.
Because TB is a controlled veterinary disease, once the research group found TB in Kruger rhinos in 2016, the Department of Agriculture, Land Reform, and Rural Development imposed restrictions on translocating rhinos from the park to prevent spreading the infection to other populations.
These restrictions affect rhino conservation in other locations; the Kruger has been an important source of rhinos for other areas where new populations are being established or for genetic diversity in established populations.
A TB screening test was recently approved by the department and a management strategy involving a quarantine protocol with SANParks was devised, allowing for the translocation of rhinos out of the Kruger.
TB still poses a threat to rhino populations and it is still ‘a cause for concern’, says Dr Carmel Witte, a senior author of the study.
‘Tuberculosis tends to be a disease that manifests over long periods of time and when you compound an infectious disease with stochastic events such as climate change and unprecedented mortality due to poaching of endangered animals.
‘Continued surveillance of rhinoceros, as well as other animals, can help us understand the long-term impact of this disease in wildlife and prevent catastrophic population losses and further disease spread,’ she says.
‘To avoid the next pandemic in people,’ says Wynand Goosen, Fellow at the Animal TB Research Group, ‘livestock and wildlife will have to be actively monitored for various infectious pathogens with zoonotic potential.’
Picture: Getaway Gallery
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