Lions at a South African zoo that caught the coronavirus from their handlers were sick for more than three weeks and continued to test positive for up to seven weeks, according to a new study that raised concerns about the virus spreading among animals in the wild.

It is not clear how much virus the lions were carrying or whether they were actively infectious for the whole period that they tested positive. But prolonged periods of infection in big cats would raise the risk that an outbreak in the wild might spread more widely and infect other species, researchers said. That might eventually make the virus endemic among wild animals, and in a worst case, give rise to new variants that could jump back to humans…

“If you don’t know that its Covid, there’s a risk that it can then spread to other animals and then potentially back to humans,” said Dr. Venter, a professor of medical virology, who teamed up with a wildlife veterinary scientist for this study. The animals were infected long enough “that the virus can actually undergo mutations,” she said, “but the risk is more that if you’re in a wildlife reserve and it spreads into the wild it can then become endemic.”