How humans are spreading disease to other great apes
Close encounters with tourists may be exposing great apes to COVID-19.
New research shows that encounters between tourists and wild mountain gorillas are close enough to risk the transmission of infectious diseases – including COVID-19.
The current pandemic hadn’t hit when Magdalena Svensson and colleagues from Oxford Brookes University started monitoring photographs of wild gorilla encounters on social media. Their aim was to gauge how well tourists adhere to guidelines designed to minimise the risk of infecting the apes with human diseases.
The team found that in only 3 per cent of 858 photographed interactions was the recommended 7m distancing respected. It was discovered that 86 per cent of photos showed people approaching within 4m of the great apes, and there were 25 instances of physical contact. Face masks, which are also encouraged, were worn in 65 per cent of encounters.
But early last year, the research took on extra significance. “When COVID-19 hit, we were in the middle of writing it up,” Svensson explains.
It emerged that non-human primates are also susceptible to coronavirus. Indeed, macaques have been used by scientists to investigate immune responses to infection. Then, in January, it was announced that gorillas in San Diego Zoo had tested positive for COVID-19. Some showed mild symptoms, and all have now recovered. But Svensson points out that this was with the benefit of veterinary care.
“We know too little about how it affects primates, especially wild ones – it’s not worth risking it,” says Svensson. “We have just over 1,000 mountain gorillas left.”
“We do know that respiratory illness is a leading cause of morbidity and mortality in mountain gorillas, after trauma,” says Kirsten Gilardi, chief veterinary officer at Gorilla Doctors, based at the University of California, Davis. “In some cases we have determined that the initial infection was a human virus that led to a secondary bacterial pneumonia.”
Gladys Kalema-Zikusoka, CEO of Conservation Through Public Health in Uganda, goes further. “A majority of the infections that have caused mortality in gorillas come from people,” she says.
In this respect, says Svensson, COVID-19 presents an opportunity to reassess the risks of transmission of all infections.
People were approaching within 4m of the great apes, and there were 25 instances of physical contact.