The Coronavirus Menagerie

Barbara Han, a disease ecologist at the Cary Institute of Ecosystem Studies, knew it was a question of when, not if, the coronaviruses would spread to animals. She began working on an artificial intelligence model that would predict which animals would be next after the first reports of infections.

We had a lofty goal of being able to predict which species we should be keeping an eye on. The trickle of cases in new species became a flood as her team worked. The coatimundi, which is native to the Americas, and the binturong, which is native to Southeast Asia, are two species that have been affected by the virus.

540 mammal species were identified by Dr. Han and her colleagues as being most likely to host and spread the coronaviruses. She was worried that the red fox, which is widespread in Europe and North America, would be susceptible to the virus.

Dr. Han exclaimed when he was informed of the finding.

Scientists analyzing tissue samples from dead white-tailed deer in Iowa found that the virus was widespread in that species. Concerns about the spread of the virus to other species, including back to humans, were intensified by the discovery. What else could deer do to spread the coronaviruses? What else will happen?

There is no need to panic because the animals are not to blame, according to experts.

Identifying the species at risk is crucial for protecting both human and animal health. It is a formidable scientific problem, with a wide array of vulnerable species. Computational predictions, laboratory data and confirmed infections in zoos, homes and the wild must be analyzed by scientists.

In an ideal world, scientists would be watching every population. In the real one, they are trying to strike a delicate balance between identifying the species of highest concern and casting a wide net as the virus changes.

Scientists use a variety of tools. Each approach has limitations, but together they show a full picture of which animals are at risk.

Some research teams are looking at the ACE2 receptor, a molecule found on the surface of the cells of many species. The coronaviruses's spiky protrusions allow it to bind to these receptors, like a key in a lock, and enter cells.

A group of scientists compared the ACE2 receptors of hundreds of mammals with those of humans to see which species the virus might affect. Ours is not similar enough to raise concern.

The predictions have been very good so far, according to Harris A. Lewin, a Biologist at the University of California, Davis. White-tailed deer were predicted to be at high risk for infections by the scientists.

In April 2020 the paper identified the strain of the virus that raged through the farms as very low and very low concern.

It's important to remember that a snapshot of susceptibility is only one of the factors that can affect a person's susceptibility to a disease.

A biased data set has been created by scientists who have mapped the ACE2 receptors of just a few hundred mammals. Model organisms used in experiments, species that carry other diseases, and charismatic zoo denizens are not necessarily the animals people are most likely to encounter.

We would be like, "What's wrong with us?" if there was a squirrel-inspired epidemic. The basic biology of a squirrel was not measured.

Scientists have to come up with new ways to make predictions for animals. Basic biological functions, such as regulating blood pressure, are performed by the ACE2 sequence. By collecting basic life history details of a species, Dr. Han's team was able to identify those that were likely to bind to and transmit the virus.

Computational predictions can be tested in the lab by trying to get animal cells or live animals to carry a virus. One study found that deer mice could be carriers of the original version of the virus, while house mice could not.

What happens in a collection of cells does not always happen in real animals, and what happens in a lab, where animals typically receive high doses of the virus, may not reflect real life. Researchers found that pigs do not appear to be highly susceptible to the original virus.

Scientists can use serology studies to find out if animals have been exposed to the coronaviruses in the real world.

The discovery of widespread antibodies in white-tailed deer made scientific alarm bells ring because it indicated that many of the animals had already been exposed to the virus. Researchers found active infections in the cervids after it prompted them to look for them.

It can be difficult to sample and collect free-ranging animals. The US Department of Agriculture, which received $300 million under the American Rescue Plan, is now asking zoos, aquariums and wildlife facilities to send in blood samples, which will be analyzed for coronaviruses.

Wildlife rehabilitation specialists have been enlisted by researchers at Tufts to take samples from a wide range of animals. Bat rehabilitators often submit samples of their saliva, which can be difficult to get from the animals. All have been negative so far.

Bats are a source of concern because they are a reservoirs for other coronaviruses. Not all of the bat species are susceptible to the virus, a reminder that animals of highest concern may not be intuitive.

Complicating matters, the virus is not static, and animals that resisted infection with previous versions might be vulnerable to new ones. Lab mice that were not susceptible to the original coronaviruses or the Delta variant were susceptible to the other two.

The problem with emerging diseases is that you have to keep resetting your knowledge.

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The susceptibility of a species depends on a number of factors.

A species's relationship with us is very important for a virus that is overwhelmingly transmitted by humans. They are not likely to run into us because of their high risk for infections. In 2006 a bottlenose dolphin in a marine park in North America was likely transmitted to by a human.

The risk to pets is manifest and we have heard stories of dogs getting infections from people sharing food and licking off their plates when they were sick.

Pets can be affected by the virus. Two people are likely to have been bitten by hamsters in a Hong Kong pet store.

Many of the infections we will get from our pets will be dead ends, scientists predicted. Your hamster at home that you may have bought a while ago is not a high risk to you.

In North America, there are deer mice, red foxes and cats that live alongside us but are free to roam. The animals may act as a bridge between humans and wild populations. Rodents should be on the top of the list.

The U.S.D.A and other agencies are looking for signs of the virus in animals that live in and around zoos.

Certain threatened species are a top concern around the world. Three snow leopards in a Nebraska zoo died after contracting the coronaviruses, and a wild leopard in India was found to be infectious.

Great apes are vulnerable to other respiratory viruses because they are closely related to humans.

No coronaviruses have been reported in wild apes so far, but researchers are monitoring the animals closely, collecting fecal samples from those with respiratory illnesses.

Andrew Bowman is a veterinary epidemiologist at Ohio State University.

To keep an eye on the changes in animals and the possibility of them being transmitted across species, federal researchers are comparing virus samples from animals with those from humans in close contact with them.

Researchers are looking at possible variations. Dr. Kuchipudi and his colleagues created a model that generated novel patterns of mutations and then looked at whether they would make the virus more likely to harm cows. Scientists will be able to watch for those changes in databases and observe cattle more closely.

The longer-term threat of viral recombination, in which an animal is simultaneously exposed to two coronaviruses that swap genetic material, is worrying scientists. Researchers at the University ofLiverpool created a model predicting potential hosts in which coronaviruses could recombine.

Long-term funding and commitment is needed to stay ahead of the virus. Making these investments now could result in better systems for monitoring pathogens in other species and an expanded understanding of how animal health is linked to ours. It could help experts catch the next health threat before it gets to animals.

There is no harm in understanding the world around us.