At least two gorillas at San Diego Zoo in the US state of California have caught the coronavirus, the first known instance of natural transmission to great apes, officials said on January 11.

Two primates began coughing last week and have since tested positive for Covid-19, while a third is showing symptoms, governor Gavin Newsom said.

They are thought to have contracted the virus from an asymptomatic zoo worker, though this has yet to be confirmed.

The zoo’s executive director Lisa Peterson said: “Aside from some congestion and coughing, the gorillas are doing well.

“The troop remains quarantined together and are eating and drinking. We are hopeful for a full recovery.”

Gorillas share up to 98 per cent of their DNA with humans, and studies have found that some non-human primates are susceptible to Covid-19 infection.

It is not yet known if the gorillas will have a serious reaction to the disease that has killed 1.94 million humans, or if other troop members have also been infected.

The San Diego Zoo Safari Park, where the gorillas are kept, has been closed to visitors since early last month as record cases began surging through Southern California.

Workers are all required to wear personal protective equipment such as masks when near the gorillas, the zoo said.