More than 400 rescued orangutans are being kept in quarantine amid fears coronavirus could wipe out the population in the wild.
The Borneo Orangutan Survival Foundation treats adult apes so they can return to their natural habitat and trains young orphans to gain survival skills.
But plans to release orangutans ready to go back into the rainforest have been put on hold over fears the virus could spread to those in the wild, already threatened by habitat destruction and poaching.
Ben Callison, managing director of Borneo Orangutan Survival UK, said the risk of transmission from human to ape was a real threat.
He said: “We share 97% of our DNA with orangutans.
"HIV, hepatitis, tuberculosis, even the common cold can be transmitted to an orangutan.
"So the likelihood of them getting coronavirus is very high.
"We are not taking any risks, which includes not only our sanctuary, but ensuring we don’t see this get into wild populations.
“The virus could devastate those populations if it does have an equal or worse mortality rate than we’ve seen in humans.”
Orangutans that display symptoms will be isolated.
The largest primate rescue and rehabilitation project in the world closed to the public at the end of March.
Staff are required to wear medical grade masks and gloves.
But the organisation said the lockdown had brought challenges with visitor donations drying up as well as soaring prices in Indonesia for personal protective equipment.
An appeal has been launched after the charity said many supplies have increased by “800%”.
Ben Callison added: “You can imagine the huge scale in caring for all 400 plus orangutans.
"Our focus is keeping the orangutans in our care safe, no matter the cost.
“It would be devastating to have asymptomatic orangutans released into the wild only to have it start an outbreak in that wild population.”
Orangutans are Asia’s only great ape found on Sumatra and Borneo.
