World Wildlife Day: silencing the roars of the king
2018-03-02 14:28
Taime Sylvester
"Nants ingonyama bagithi Baba", the Zulu phrase translating to "Here comes a lion, Father" has been sung across the world since the opening scene of The Lion King movie in 1994.
How my mind wanders to an African plane as the setting sun paints the darkening sky orange and red, and the animals gather around the watering hole as if coming together to recount the long day now behind them.
A sudden silence befalls the chattering animals, and in the distance the majestic roars of a lion is heard. Powerful, exciting, terrifying and beautiful. The animals stand with ears perked, as if in reverence for their King.
But I am abruptly brought back to this reality, left to wonder if my children will ever know the excitement of seeing Africa's majestic king wandering free in the Savanna. Or will the relayed stories of my ancestors ring like things of fairy tales filled with seemingly magical beasts of days long gone?
Given the precarious situation of this iconic species, it should come as no surprise that the theme of this year's World Wildlife Day (3 March) celebrations is Big cats: Predators under threat.
Among the big cats, lions in particular are in serious trouble. Over the past two decades, lion numbers have declined sharply due to shrinking habitats, disease and trophy hunting. Free ranging populations are now confined to living in small, isolated populations, with less than 3500 wild lions roaming freely in South Africa's Kruger National Park.
In wildlife sanctuaries like the Kruger National Park lions face a new threat, a clever killer called tuberculosis (TB). This area is endemic for Mycobacterium bovis, which causes bovine tuberculosis and is closely related to human tuberculosis. It is believed that M. bovis first entered through southernmost point of the park, when it was transmitted to buffalo from neighbouring infected cattle. Just as in humans, TB is a highly infectious and devastating disease in animals.
Lions are repeatedly exposed to M. bovis and experience a high infection pressure when they eat infected carcasses. To date 27 species of animals have been confirmed as M. bovis infected in the Kruger, all of which appear on the lions' menu.
Unfortunately, the majority of lions appear healthy and symptoms like swollen joints, slow-healing wounds, poor coat condition, weight loss, coughing and difficulty breathing only appear with advanced disease. At this late stage of disease lions are believed to shed infectious material, driving intra-pride transmission.
In highly social species such as lions infectious diseases like tuberculosis can spread like wildfire, highlighting the importance of developing diagnostic tests and increased wildlife research. The development of blood-based tests allow for the investigation of the complex and multifaceted host immune response without the stress and danger associated with keeping wild animals captive.
Understanding infectious diseases and host responses allow conservation managers to make better decisions and ensure the future survival of the species. The Animal TB research group at Stellenbosch University has developed a blood test able to accurately pick up early stage M. bovis infection in lions. Recently, using this newly developed tool, which measures immune responses specifically to TB causing bacteria, our research group has reported that 54% of lions tested in the southern part of the park are infected with M. bovis.
For conservation of this species the early detection of infected lions is crucial, especially when decisions regarding animal movement and population genetics need to be taken.
The importance of lions and their conservation in countries such as South Africa are multifold. In areas where tourism is a pillar of the economy, the loss of lions could influence the quality of life and survival of many families. Moreover, as an apex predator the lion has a considerable top-down influence to maintain the ecosystem it lives in. The loss of this species could have catastrophic effects on an often already fragile ecosystem.
The current rate at which we are closing in on the already minute habitat of wild animals, especially big cats, is alarming. This concern should only grow when we realise the many challenges these animals face, including multiple assaults by infectious pathogens. It is time to creatively think of conservation initiatives and come up with innovative ways to study and save lions and other big cats, so that we are never faced with the silencing of this King.
- Dr Taime Sylvester is a postdoctoral researcher in the Division of Molecular Biology and Human Genetics at the Faculty of Medicine and Health Sciences at Stellenbosch University. She specialises in understanding the host immune response of lions to tuberculosis infection, with a special interest in T-cell immunology.
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