VN March 2023

Vetnuus | Maart 2023 16 Infected, but Asymptomatic The researchers emphasized that the presence of infection does not mean that the animals are diseased or dying. Professor Michele Miller, who leads the Animal TB Research Group and is the National Research Foundation (NRF) South African Research Chair in Animal TB, said their research shows that most of the infected rhinos can contain the infection if they are otherwise healthy. “It can be compared to humans who are infected with COVID-19 or have latent TB but are asymptomatic,”Miller said. “The infected rhinos are harbouring the bacteria, but their immune system keeps it in check. 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 infected. They can potentially live for years with infection if it is contained.” Witte added that the eventual population-level health effects of bTB are currently unknown. “Tuberculosis tends to be a disease that manifests over long periods of time, andwhen you compound an infectious diseasewith events such as climate change and unprecedented mortality due to poaching of endangered animals, it is cause for concern,”she said.“Continued surveillance of rhinoceros and other animals can help us understand the long-term impact of this infection in wildlife and prevent catastrophic population losses and further disease spread.” Wynand Goosen, PhD, Wellcome International Training Fellow in the Animal TB Research Group, highlighted the importance of further developing diagnostic tools and a “Tuberculosis One Health” approach. “Even though our research is very important from an animal conservation perspective, it is just as important from a human health-risk perspective,” Goosen said. “To avoid the next pandemic in people, livestock and wildlife will have to be actively monitored for various infectious pathogens with zoonotic potential. This requires appropriate diagnostic tools that are rapid and accurate.” Risk Factors The study, which was published in the American scientific journal PNAS (Proceedings of the National Academy of Sciences) today (June 6, 2022), identified proximity to buffalo herds (for white rhinos) and a sampling year (for black rhinos) that coincided with periods of drought as risk factors for M. bovis infection. A significant cluster of cases was detected near Kruger’s southwestern border, although infection was widely distributed across the rhinos’ range in the large national park. The identified cluster is close to the park’s border with the surrounding Mpumalanga province, consisting primarily of farmland with livestock herds that have historically been implicated in the spillover of M. bovis to wildlife in Kruger, especially to buffalo. Dr Peter Buss, senior veterinary manager in Kruger National Park’s Veterinary Wildlife Services, added there is no evidence to suggest that bovine TB will have any impact on the population. “The rhinos are being exposed to the organism, they are mounting an immune response, but they are not getting sick and dying from it,”he said.”The same applies to other species. For example, we know that we get TB in our lions and that individuals will die of the disease. But if you look at the population level of the disease, lions seem to be doing fine, and their numbers have remained fairly static.” The authors further emphasized that the findings were not a surprise since bovineTB is prevalent in at least 15 other species in Kruger—one of Africa’s largest reserves—but that their research has significant positive implications for SANParks’rhino conservation and management strategy. “While this pathogen may not appear to impact the health of rhinoceros individuals drastically, it has significant implications for conservation management decisions,” explained Rebecca Dwyer, lead author of the study and a PhD candidate in the Animal TB research team. “For example, tuberculosis testing in KNP rhinoceroses that are earmarked for translocation for conservation reasons can increase confidence of minimal risk of spread to other susceptible individuals at their destinations.” Significance “With South African rhinos being threatened by poaching, habitat loss and drought, it is key to be able to translocate them to strongholds where they can be kept safe and to preserve their genetic diversity,” said Miller. “But bovine TB is a controlled veterinary disease, so once Article They can potentially live for years with infection if it is contained Research in all susceptible species is of the utmost importance to develop these tools