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Interconnected: Human and animal TB part of the same problem
Author: FMHS Marketing & Communications / FGGW Bemarking & Kommunikasie – Ilse Bigalke
Published: 20/03/2023


Tuberculosis (TB) in humans cannot be eradicated unless TB in animals is also eliminated, as these two diseases are closely interconnected.

This is the central message the Animal TB Research Group at Stellenbosch University's (SU) wants to convey on World TB Day.

World TB Day is observed annually on March 24 to raise awareness about TB and the efforts made to end this global epidemic. The date marks the day in 1882 when the bacterium causing TB was discovered, and this year's theme is “Yes! We can end TB!"

The main focus of the Animal TB Research Group, situated within SU's Faculty of Medicine and Health Sciences (FMHS), is to break the transmission of TB that occurs between wildlife, livestock, and people.

In a vid​eo produced for World TB Day 2023, scientists examine the death of an elephant in the Kruger National Park (KNP) due to TB in 2016.

Prof Michele Miller, who leads the group, says the death of this elephant perplexed scientists. “Bovine TB (caused by the bacterium Mycobacterium bovis) was definitively diagnosed in KNP wildlife in 1990, but this case was different. It turned out that the elephant suffered from human TB."

This was the first time that scientists had identified a fatal case of human TB in a wild African elephant. But how is it possible for wild animals to get infected with human TB?

“TB is often only thought of as a disease that affects humans, when in fact it is a multi-host disease," explains Miller. Although animals are typically infected with Mycobacterium bovis and humans with Mycobacterium tuberculosis, reports increasingly have found reverse infection from animals to humans and vice versa.

“Infected wildlife populations, such as KNP, can result in spread of Mycobacterium bovis across boundaries between parks or reserves to livestock in communities, and subsequently to humans. These bacteria can also contaminate soil and water and infect other species. In areas where there is a high human TB burden, such as South Africa, people may discard food or other waste which could be picked up by an elephant, which may spread human TB to these animals," the scientists explain.


Bovine TB was introduced in South Africa when infected cattle were imported during the early European settlements. “Primarily, it has been a disease of domestic cattle and it was only since the 1990s that we've been really aware that it can spill over from domestic animals into wildlife in Kruger National Park," says Dr Peter Buss, Veterinary Senior Manager in KNP's Veterinary Wildlife Service.

Today animal TB in the KNP affects more than 20 species, including buffalo, kudu, lion, antelope, rhinoceros and elephants.

Economic implications

TB in animals not only have major health implications for South Africa, but also severely affects the economy. Many rural communities rely heavily on cattle as a food and milk source and agriculture focussed on livestock is one of the major contributors to the country's gross domestic product (GDP).

Cattle affected by bovine TB will lose weight and produce less milk. And if any infection is detected, a farm will be placed under quarantine and the animals may be slaughtered without compensation for the owner. This has a major effect on food security and livelihoods.

Importance of research

Early detection of TB is extremely important for both economic and health reasons. “To do that, we have to be able to determine whether animals are infected by Mycobacterium bovis," the scientists explain.

It has always been very difficult to diagnose bovine TB due to the limited tests that are available for wildlife. Species-specific reagents (for instance for rhinoceros, elephants, and lions) are not commercially available.

Initially the group could only test animals after their demise, either due to natural causes or from clinical symptoms of TB, but their research has since enabled diagnosis in living animals, and in multiple species. This is done using samples collected from anaesthetised animals, and testing it in SU laboratories for the presence of the TB pathogen.

“SU is taking testing to another level by looking at the epidemiology of the disease," Buss comments.

TB One Health approach

The Animal TB Group highlights the importance of the further development of rapid and accurate diagnostic tools and of a “One Health" approach, which recognises the interconnection between human, animal and environmental health.

“We are saying that the TB problem is not a one-directional issue. If we don't take care of the TB problem in our domestic animals and wildlife species, there may be overspill into humans and that will add to the total human TB burden," they conclude.