JOHANNESBURG — Lions at a South African zoo that caught the coronavirus from their handlers had been sick for greater than three weeks and continued to check optimistic for as much as seven weeks, in accordance with a brand new examine that raised considerations concerning the virus spreading amongst animals within the wild.

It isn’t clear how a lot virus the lions had been carrying or whether or not they had been actively infectious for the entire interval that they examined optimistic. However extended durations of an infection in huge cats would increase the chance that an outbreak within the wild may unfold extra broadly and infect different species, researchers stated. That may finally make the virus endemic amongst wild animals, and in a worst case, give rise to new variants that might leap again to people.

The study at the University of Pretoria is probably going the primary of its form in Africa. Researchers started to watch captive wildlife in zoos and conservation sanctuaries after a tiger on the Bronx zoo got sick with the coronavirus in April 2020, in accordance with Professor Marietjie Venter, the principal investigator on the examine.

The analysis workforce monitored two pumas that contracted the coronavirus at a personal zoo in July 2020, throughout South Africa’s first pandemic wave. The pumas, which aren’t native to South Africa, began displaying signs, together with lack of urge for food, diarrhea, runny noses and chronic coughs. Each cats made a full restoration after 23 days.

A few yr later on the identical zoo, three lions started to point out related signs. One of many lions, an older feminine, developed pneumonia. The lion’s handler and an engineer on the zoo additionally examined optimistic for the virus.

This time, researchers had been capable of sequence the samples and located that the lions and their handler had been contaminated with the identical Delta variant. The sickness developed by the lions, significantly within the older feminine, confirmed that animals, like folks, may develop extreme signs from Delta, which drove South Africa’s deadliest pandemic wave.

The lions recovered after 25 days, however had optimistic P.C.R. checks for greater than three extra weeks. P.C.R. checks amplify the virus’s genetic materials and due to this fact can detect even very small quantities. The info recommended that the quantity of virus the lions had been carrying decreased over these weeks, and it was not clear exactly how lengthy they had been infectious.

In a captive setting, the animals had been saved in quarantine, however in bigger parks dotted round South Africa, the place lions are a typical public attraction, controlling an outbreak may show “very, very tough,” the examine stated, significantly if it had been undetected. These lions are sometimes fed by people fairly than trying to find themselves, growing their publicity.

“In case you don’t know that its Covid, there’s a danger that it could actually then unfold to different animals after which doubtlessly again to people,” stated Dr. Venter, a professor of medical virology, who teamed up with a wildlife veterinary scientist for this examine. The animals had been contaminated lengthy sufficient “that the virus can truly bear mutations,” she stated, “however the danger is extra that in the event you’re in a wildlife reserve and it spreads into the wild it could actually then turn into endemic.”

The coronavirus driving the worldwide pandemic seemingly originated in bats and finally jumped to people, in what is named “spillover” infections.

Scientists warn that “spillback” infections of people infecting animals — as have occurred with mink, deer and home cats — may ravage complete ecosystems within the wild. Infections that reached the wild may additionally develop the virus’s potential to unfold unchecked and mutate in animals, doubtlessly into variants harmful to people.

One well-studied phenomenon includes infections among large populations of captive mink. At one mink farm in Denmark, the virus mutated into a brand new pressure through the change from human to mink, prompting the mass slaughter of the animals all through that nation and Europe to stop its unfold again to people.

Against this, the South African examine concerned small outbreaks, however Dr. Venter famous that the unfold in mink reveals the potential hazard of bigger outbreaks in wildlife.