Fears over animal link to COVID-19 spread

Scientists call for more work to explore connection amid infection uncertainty

Scientists are warning that the novel coronavirus may be establishing itself in a growing number of animal hosts which could lead to future reintroductions of the pathogen into humans.

Researchers at University College London, or UCL, have called for a global effort to monitor animal populations and determine which creatures can harbor the virus.

Joanne Santini, a professor of microbiology at UCL, said there is increasing evidence that some animals can catch novel coronavirus from people, and might subsequently transmit it to other people.

"But we don't know just how much of a risk this is, as it's an area of study that has not yet been prioritized," Santini said. "We need to develop surveillance strategies to ensure we don't get taken by surprise by a large outbreak in animals, which could pose a threat not just to animal health but to human health as well."

Santini and her colleague Sarah Edwards, who is a bioethics professor at UCL, reviewed a number of studies of COVID-19 in animals before publishing a commentary in the medical journal The Lancet.

Novel coronavirus is what is known as a zoonotic disease, meaning it can spread from animals to humans. Bats and pangolins have both been implicated in the initial novel coronavirus outbreaks.

Experimental evidence has shown that COVID-19 can infect a variety of other animals, including monkeys, ferrets, cats, and hamsters.

This month, the Dutch government ordered the culling of 10,000 mink after infected animals were found on 10 farms in the Netherlands, where they are raised for their fur. Dutch authorities said the culling was necessary as there is a chance that mink could act as long-term reservoirs of the disease.

Edwards says that the results from computational studies suggest attention should also be paid to rabbits, sheep, goats, cattle, and horses.

These computer studies look at the interaction between the novel coronavirus surface proteins and receptors on the membranes of various animal cells. In humans, the virus can enter cells via the ACE-2 receptor, which is found in the lungs and other tissues. Various other animal species also have cells with ACE-2 receptors.

A study in March led by Hunan University in China identified a number of species that the virus might be able to infect, including pangolins, cats, cows, buffalo, goats, sheep, pigeons, civets, and pigs.

"There's an urgent need for widespread surveillance, by testing samples, preferably non-invasively, from large numbers of animals, particularly pets, livestock and wildlife that are in close proximity to human populations," said Edwards. "More laboratory experiments on small numbers of animals are unlikely to give us the evidence needed to be confident that certain species are entirely safe, making major surveillance work the only real option here."