Home Science Bovine tuberculosis: another threat to African rhinos

Bovine tuberculosis: another threat to African rhinos

Bovine tuberculosis: another threat to African rhinos

African rhino populations are currently threatened due to several factors including poaching, habitat destruction and the effects of climate change.

ONE new studiopublished in the magazine PNASdetected infection by Mycobacterium bovisbacterium that causes bovine tuberculosis, in African rhinoceros species from Kruger National Park (KNP), in South Africa, historically the population largest in the world free.

KNP is considered endemic for bovine tuberculosis, with the African buffalo (Syncerus coffee) main maintenance guests.

African rhino populations are threatened by a number of factors, including poaching, habitat destruction and the effects of climate change.

The work, led by the animal tuberculosis research group at Stellenbosch University in Cape Town, looks at infection by M.bovis in black rhino populations (Bicorni Diceros) it’s white (Keratotherium simum) that meet loose at KNP. The studied samples were collected between 2016 and 2020 and come from 437 specimens.

“We found evidence of generalized infection per M.bovis in African KNP rhinos with a substantial infectious burden,” the authors write. Infection levels were similar across the study area and for all animal populations studied.

the transmission of Mycobacterium bovis

Using statistical models, the researchers analyzed the chances of infection by this mycobacterium in rhinos. The results show a higher probability of infection in white rhinos due to their proximity to African buffalo herds.

Since the latter are maintenance guests important for M.bovis in KNP, the authors suggest that the infection spreads from these animals to white rhinos that share the environment. an important proximity for African buffalo herds may be a good predictor of infections in white buffaloes.

Mycobacteria are very resistant and can survive in the environment for weeks or months.

Michele Miller, University of Stellenbosch

Michele Miller, leader and author of the Animal Tuberculosis Research Group, explains: “The infected buffalo probably coughs periodically; in this way, your saliva and respiratory secretions contaminate vegetation and habitat. Mycobacteria are very resistant and can survive in the environment for weeks or months.”

Infections in black rhinos were higher in the early years of the study period (2016-2018) than in the later years (2019 and 2020), which coincided with the rainy seasons. intense drought. The researchers indicate that this may suggest the contribution of drought, as well as other climatic conditions, to the risk of contagion for the black rhino.

Miller explains: “It is not possible to know exactly when M.bovis infected for the first time rhinos, but we only detected cases in 2016, during a drought, when the animals’ physical condition was poor and therefore their immune systems were likely compromised.”

“It may have been circulating in the rhino population before these cases, but until recently we didn’t have any. test to detect themthis is possibly why no cases have been documented,” he adds.

Historically, it is believed that M.bovis originated in the KNP in the 1960s and 1980s, from infected domestic cattle which was in the areas adjacent to the boundaries of the park. However, in buffalo the bacteria was not detected until 1990. Since then, infections have been documented in 15 other wild species of KNP.

ONE recent analysis of the possible scenarios interspecies transmission suggests that the rhino can be infected with M.bovis in ecosystems that harbor other infected hosts. Likewise, the interspecies dissemination of this bacterium has been demonstrated in other contexts, such as wild boar, deer and cattle in Spainand others in UK s USA.

Miller explains: “It is possible that rhinos could contain the infection and possibly even eliminate it, if they are healthy. We have studies underway to determine how long an infected rhino can remain positive; however, answering that question will take years.”

M. bovis is believed to have originated in Kruger National Park from infected domestic cattle.

The mechanisms of transmission between herbivores are not well understood, but are attributed to the indirect interaction through shared resources, such as pasture, feed, or water wells, that are contaminated by infected animals that shed the bacteria through their feces and body fluids.

In the park, black and white rhinos share environmental resources with animals of many species, such as African buffalo, great kudu (Tragelaphus strepsiceros), wild boar (Phacochoerus africanus), which can be infected by M.bovis.

Monitoring diseases in ecosystems wild

Once infection by this bacterium is chronic and clinical signs of the disease can take months or even years to appear, its presence can go unnoticed for decades, as has been documented in several wild populations around the world.

For species considered threatened any endangeredsuch as the black and white rhino, the presence of an infectious disease and the measures taken to contain it can significantly hamper conservation efforts and potentially affect the health and survival of the population.

In the case of rhinos, the translocation of individuals to other populations is an integral part of conservation strategies and historically KNP has been an important source of these animals for other populations. bastions of conservation in South Africa and other African countries.

Characterizing the threats to the survival of rhinos in the KNP is of vital importance for the conservation and protection of other vulnerable populations.

The regulations imposed on the KNP because of the diagnosis of M.bovis in several species are an additional barrier to the movement of rhinos from the park to other national or private reserves. This can have a impact important in the conservation of these animals.

characterize the threats to survival of rhinos in the KNP is of vital importance for the conservation and protection of other vulnerable populations, the authors note.

How bovine tuberculosis can also affect domestic animals and for humans, its spread to different areas can have serious consequences for the human and animal health and consequently for the agricultural and tourism industries in Southern Africa.

According to the authors, the results of this study emphasize the importance of monitor diseases in wild ecosystems and support current quarantine and diagnostic testing requirements for KNP rhinos.

This survey provides an opportunity to raise awareness of the overall impact that tuberculosis and other zoonotic pathogens may have on domestic and wild animal populations, food security, and the conservation of species and ecosystems.

One of the key messages to keep in mind is that people, animals and the environment are interconnected. To understand zoonotic pathogens, it is crucial to analyze each of these relationships.

Michele Miller, University of Stellenbosch

Miller explains: “One of the key messages we need to keep in mind is that people, animals and the environment are interconnected. To understand zoonotic pathogens, it is crucial to analyze each of these relationships.”

The authors suggest that future research should focus on the development of diagnostic tools that can improve surveillance in KNP species. “In our research group we are carrying out studies on tuberculosis in lions, leopards, cheetahs, elephants, buffaloes, antelopes, warthogs and African wild dogs,” says Miller.

“Predators are mainly infected by eating infected prey (such as buffalo, kudus, etc.). In these species, the infection usually leads to a debilitating disease. One explanation could be that they are exposed to much higher doses of M.bovis than herbivores”, he concludes.

Reference:

Dwyer et al.Epidemiology of Mycobacterium bovis infection in free-ranging rhinos in Kruger National Park, South Africa. Proceedings of the National Academy of Sciences (PNAS)

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