The African lion from the Singapore Zoo that showed signs of sickness on Monday has tested positive for Covid-19, said the Animal and Veterinary Service (AVS) last night.
It is the fifth lion to be infected with the coronavirus, after four Asiatic lions from the Night Safari tested positive on Tuesday.
The faecal sample taken from the African lion was positive for the Sars-CoV-2 virus in a polymerase chain reaction (PCR) test, said AVS.
"AVS had previously issued an order under the Animals and Birds Act to Mandai Wildlife Group to isolate the nine Asiatic lions and five African lions as two separate groups, within the Night Safari and the Singapore Zoo respectively," it added.
This includes the five lions that tested positive. All lions are isolated within their respective dens.
A spokesman for Mandai Wildlife Group, which runs the Singapore Zoo and other wildlife parks, said in a statement last night that all its lions that have been unwell are "bright, alert and active for now".
"While we expect them to fully recover soon, we are monitoring them very closely. We have added vitamin C to their diet but have not needed to administer other medications," the spokesman added.
The Mandai Wildlife Group said on Tuesday evening that none of the animals at its wildlife parks has been vaccinated against Covid-19 and there are no plans to do so.
Responding to queries from The Straits Times, it said that more understanding of the safety and efficacy of vaccination for animals is needed. "We are checking with our global zoo counterparts who have started trialling vaccinations for some of their high-profile animals."
Since September, 48 animals at the Oakland Zoo in California, including lions, bears and ferrets, have been inoculated with an experimental vaccine for animals by veterinary pharmaceutical company Zoetis.
In January, apes living in the San Diego Zoo were inoculated with the same vaccine after a Covid-19 cluster was detected among a troop of gorillas living there.
In March, Russia registered a Covid-19 vaccine for animals, with tests showing that it could generate antibodies against the virus in dogs, cats, foxes and minks.
Dr Sonja Luz, vice-president of conservation, research and veterinary at Mandai Wildlife Group, said on Tuesday: "The animal care teams are keeping a close watch on all higher-risk species, including primates and carnivores, under their care. No other animals across the four wildlife parks currently present clinical signs of the virus."
Professor Dale Fisher, a senior consultant at the National University Hospital's Division of Infectious Diseases, said that if an animal has close exposure with humans and has the same ACE2 receptor as humans on its respiratory lining, it can also get infected.
The Sars-CoV-2 virus binds with the ACE2 receptor to infect host cells. He noted that this happened commonly in minks and resulted in millions being culled.
Professor Wang Linfa from the Duke-NUS Emerging Infectious Diseases programme noted that more than 10 mammal species, other than humans, have been infected.
He said that while humans can infect pets, such as cats and dogs, the virus does not replicate efficiently in them. Hence the risk of infected pets passing the virus to other humans remains low.
According to the World Organisation for Animal Health, there is no evidence that animals play a role in spreading the virus to humans.
Prof Fisher said that while it is possible for the virus to spread from animals to humans, it is not common.
"We think the whole pandemic started with a spillover event - an animal somehow infected a person and after this initial seeding, human-to-human transmission took off," he added.
Dr Han Zi Yang, a veterinary consultant at VetTrust Singapore, told ST the clinic is not aware of any cases of pets in Singapore being infected with Covid-19.
"Pet owners should not be overly worried at this stage and should continue to adopt the same set of good hygiene measures in pet care. This involves regular handwashing before and after handling their pet, their food and supplies, and avoid sharing food with them," he added.
The Mandai Wildlife Group spokesman also said last night that its keepers are recovering well, but did not say how many cases were found among its staff and whether there is a workplace cluster.
"The cases likely occurred independently of each other and is reflective of the infection in the wider society," the spokesman added.
Animal care staff will be required to do antigen rapid testing weekly to reduce the likelihood of asymptomatic transmission from humans to animals.
Mandai Wildlife Group did not respond to queries on whether additional measures will be taken to keep visitors safe.
