The closures aren’t only to protect humans visiting in groups, but also for the animals themselves, which may be vulnerable to the virus.
Countries home to gorillas including Rwanda, Uganda and the Democratic Republic of the Congo (DRC) have all temporarily suspended gorilla tourism and severely restricted access to the parks, according to the organisation Gorilla Doctors, which provides veterinary care in these countries.
Furthermore, all staff must now wear masks during health checks of the primates, all people entering parks must have their temperatures checked, and boots must be disinfected.
Though a tiger in captivity in New York tested positive for Covid-19, the disease is not known to have spread to gorillas.
In a joint email to The Independent, Dr Ilka Herbinger from the WWF and Dr Fabian Leendertz, an expert in the epidemiology of highly pathogenic microorganisms at the Robert Koch-Institute in Berlin, said it was vital to protect primates from Covid-19.
“The virus is very infectious - it gets to every corner of the world. We have documented transmission of various human respiratory viruses to wild gorilla, chimpanzee and bonobo, so it is known that this happens.
“We must avoid transmission of [the coronavirus] to the great apes since it may have a detrimental effect. However, we don’t know as of yet if this virus will cause mild or severe symptoms in great apes.
“We must apply the precautionary principle, as all great apes are already highly endangered in their survival due to habitat loss, poaching and diseases.”
In a social media post, Gorilla Doctors said: “Our work continues in the face of Covid-19. Even with extraordinary lockdown measures in place, the governments of Rwanda, Uganda and DR Congo recognise the critical importance of our gorilla health monitoring.
“Our veterinary staff have received special permission to perform their work in spite of country-wide travel restrictions and stay-at-home orders to fight the spread of Covid-19.”
Sanctuaries for orangutans in Borneo have also been closed to protect the endangered animals from the outbreak.
Professor of primate biology Serge Wich, of John Moores University Liverpool, told The Independent the risks differed somewhat for orangutans and gorillas.
Asked about gorillas in central African countries he said: “Gorillas are largely terrestrial in those countries and often come in relative close contact with tourists and researchers.
“At present tourism has been halted to reduce risk. Researchers have clear protocols to maintain distance which are part of their general procedures. This should all help to reduce risk of transmission. But of course there are also other people entering these forests to collect wood, etc, so that still poses a risk as well.”
Dr Steve Unwin, a specialist in zoo health management and lecturer in biosystems and environmental change at the University of Birmingham told The Independent an estimated 40 per cent of pathogens are known to be transferable from humans and apes, and as such, strict measures are necessary.
He said: “All NGO and governmental sites involved in captive orangutan management… are taking the precautionary principle route and have stopped all but the most needed veterinary and welfare care of the animals under their care.”
But he said relevant research into respiratory disease in orangutans is pending publication.
“Before [Covid-19] hit, research had begun on pathogenic risk factors in respiratory disease in orangutans. Biosecurity measures were already in place at sites - similar to how good zoos operate - to be better able to assess the real risks from the assumed. That process is ongoing and not yet published.”
The experts also warned the fall in tourism due to the virus could eventually impact protections for great apes.
Professor Wich said: “It could lead to a shortfall for national park authorities but could also have a negative impact on local communities that benefit from tourism as well as owners of hotels and lodges. If those people need to look for alternative sources of income that could increase risk.
“In general a reduction of income due to a lack or reduction of tourism could lead to a decrease in patrols. But countries with great apes are committed to their protection so I trust they will do their utmost to continue protecting them and that is also what we hear from the field where essential patrols seem to continue even under these difficult circumstances. But at some stage financial support might be needed to continue this.”
Dr Herbinger and Dr Leendert added the virus was now “a major threat for projects which rely mainly on income from the tourism industry.”
“We are trying on multiple fronts to organise emergency funding to projects to survive these difficult times. There is great need to continue paying staff, provide continued protection to habituated great ape populations and keep anti-poaching patrols going,” they said.