From Hippos to Hamsters: How Covid Affects Creatures Big and Small | Coronavirus


A A year ago, humanity embarked on a project to vaccinate every person against Covid-19. But in recent months, a parallel vaccination campaign has also taken place. From giraffes to snow leopards, from gorillas to sea lions, zoos around the world have inoculated their animals with an experimental Covid vaccine as an insurance policy against what they fear is an equally deadly disease for some mammals.

Meanwhile, veterinary scientists have struggled to understand the scale of the Covid-19 infection in our furry housemates and what the consequences could be for their health – and ours.

Last week, two hippos at Antwerp Zoo in Belgium became the last in a coterie of creatures to contract Covid from humans. Fortunately, Imani and Hermien had no symptoms other than a runny nose, but the other animals weren’t so lucky. In November, three snow leopards died of complications from Covid at a petting zoo in Nebraska. Other zoos have reported infections in gorillas, lions, tigers and cougars.

Although Sars-CoV-2 is believed to originate from an animal, most likely a bat, until recently most of the scientific attention has, naturally, been on human cases. disease. Yet, since the early days of the pandemic, scientists have worried about the possibility of other animal infections.

“We have always recognized that coronaviruses have this tremendous ability to skip cash. So it has always been predicted that there would be a variety of domestic animals, livestock and potentially wild animals that could become infected, ”said Margaret Hosie, professor of comparative virology at the Center for Virus Research in India. ‘University of Glasgow..

If other animals can become infected and transmit the virus, it could cause it to adapt and acquire new mutations, increasing the prospect of new variants that could be passed on to humans. “You could focus on eradicating the virus from humans, but in the meantime, the virus could quietly mutate into an animal species and get hotter and hotter,” Hosie said.

The first report of animal infection came in February 2020 when a dog in Hong Kong tested positive, likely having contracted it from its infected owner. Since then, there have been numerous reports of dogs and cats with Covid. Other pets generally appear less susceptible – no one has yet identified a Covid-positive goldfish – although ferrets and golden hamsters can catch Covid-19, and Roborovski dwarf hamsters may die of it.

Other research has suggested that infections in cats and dogs are relatively common. Scientists in the Netherlands found that in 20% of homes visited where pet owners tested positive for Covid, cats and dogs had antibodies to the virus.

Some infected animals develop symptoms – usually a runny nose, cough, sneezing, or conjunctivitis – and most recover without incident. However, some may suffer from a more serious illness.

“The first cat we identified as being infected by its owner was a young kitten who died of pneumonia,” Hosie said. “We didn’t thoroughly test the other potential pathogens, so we can’t say for sure, but the pathology was very similar to the viral pneumonia seen in Covid-19 patients. “

But are these infected animals contagious? Evidence from dogs suggests that the risk of further transmission is low because it is difficult to isolate the virus that replicates from them.

On cats, the jury is still out. Experimental studies have suggested that they can infect other cats, but the degree to which this occurs in the real world is uncertain. Cats are relatively solitary creatures – they don’t spend a lot of time in close contact with other cats or humans (other than their owners). So, if they do catch Covid-19, their owner is likely the source, and any further transmission is likely to be extremely limited.

Farmed mink, on the other hand, are forced to live close to each other and are very susceptible to infection with Sars-CoV-2. They can also develop pneumonia and die from it.

In November 2020, news that the virus had passed from humans to mink, mutated and then rolled back sounded alarm bells around the world. “It was a real wake-up call, and I think that’s why there is now more emphasis on studying viruses at the human-animal interface,” Hosie said.

Fortunately, although there have been other outbreaks of mink, “so far [mink-related variant viruses] have not been shown to be more transmissible or causing a more severe impact compared to other Sars-CoV-2 in circulation, ”concluded a report from the European Food Safety Authority and the European Center for Disease Prevention and Control .

Of course, infected farm animals can be quarantined or slaughtered, as have millions of mink. Farm surveillance can also be strengthened and farm workers provided with protective equipment.

Vaccination is another option. In March, the Russian State Veterinary Service announced that it had approved a Covid-19 vaccine called Karnivak-Kov for use on fur farms or for cats and dogs, after clinical trials with arctic foxes. , cats, dogs and mink.

The US Department of Agriculture has cleared a vaccine developed by the US animal health company Zoetis for experimental use on a case-by-case basis. Earlier this year, Zoetis agreed to provide the San Diego Zoo with enough doses to inoculate its great apes after the zoo’s western lowland gorilla troop fell ill with Covid.

“Since then, we have received several inquiries from different zoos and conservatories,” said Mahesh Kumar, senior vice president of biologics research and development at Zoetis. “I think 100 species of mammals have been vaccinated.”

More worrying than breeding outbreaks, there is some evidence of significant transmission among wild animals. Vaccinating them would be impractical, assuming a vaccine works even in that species.

In May the Journal of Virology reported that white-tailed deer, which are native to North, Central and South America, were able to transmit the virus to each other. And in August, researchers at the US National Wildlife Center in Fort Collins reported that up to a third of Virginia deer in the northeastern United States, there were antibodies to Sars-CoV-2. It is not known how they got infected.

If white-tailed deer do transmit the virus to each other on a continuous and significant basis, that could be problematic – although if a new, potentially dangerous variant appeared in them, it would still have to be passed back to us, and humans don’t. don’t tend to spend a lot of time breathing the same air as deer.

“What really concerns us is the back-and-forth between humans and animals, and with other animals, in a context where the human population could ultimately be affected,” said Rebecca Fisher, assistant professor of Epidemiology at Texas A&M University. .

Its biggest fear is that the virus adapts to wild animals that live near humans, such as rodents. Fortunately, rats and mice do not appear to be particularly susceptible to infection with Sars-CoV-2 at this time.

However, due to the risks involved, it might pay off to be vigilant. “The current pandemic is maintained by man [to] human transmission, but we have to watch the animals, ”said Alan Radford, professor of veterinary informatics at the University of Liverpool.

So far, the most likely source of new variants is the continued circulation of the virus in humans. With continued high infection rates, we still pose a much greater risk to our pets than they do to us.

It is sad. “When you’re sick or recovering, what’s better than snuggling up to your pets?” Fisher said. “As difficult as it is, if we are sick we have to try not to interact with them and not pass anything on to them. We must do our best to protect them, just as we would our human children. “


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