The Danish government’s decision this week to kill millions of weasels over fears of coronavirus, effectively wiping out a major national industry, has left scientists and conservationists worried about ease Animal vulnerability to pandemic viruses and inter-zoonotic infections can be significant to humans.
The most worrying possibility is that the virus can mutate in animals and be more contagious or more dangerous to humans. In Denmark, the virus has passed from person to weasel and back to human, and has mutated in the process. Weasels are the only animals known to have transmitted the coronavirus to humans, except for the initial transmission of an unknown species. Other animals, such as cats and dogs, have been infected by human contact, but there are no known cases of people being infected by contact with their pets.
Versions of the virus that had mutated in mink and spread to humans could not transmit more or make people more sick. But one of the variants, found in 12 people so far, was less reactive to antibodies in lab tests. The Danish health authorities worry that the effectiveness of the vaccine in development may be reduced for this variant, and decide to take all possible measures to prevent its spread. This involved killing all of the country’s weasels and effectively locking down the northern part of the country where the mutant virus was found. The UK has banned visitors from Denmark who are not UK citizens.
The World Health Organization and scientists outside of Denmark say they have yet to see evidence that this variant will have any effects on vaccines. However, they did not criticize Denmark’s decision to destroy its weasel populations.
Weasel are not the only animals that can become infected with coronavirus. Genetically modified dogs, cats, tigers, hamsters, monkeys, weasels, and mice have also been infected.
Dogs and cats, including tigers, are less likely to be affected by the disease. Other animals, used in laboratory experiments, have shown different reactions. However, mink that died in large numbers in Europe and the United States, perhaps due in part to the crowded conditions on those farms, could increase exposure.
However, public health experts are concerned that any potentially infectious species could become a reservoir that allows the virus to re-emerge at any time and infect humans. This virus can mutate in other animals, as has been shown to occur in mink. Although most mutations can be harmless, SARS-CoV-2 can recombine with another coronavirus and become more dangerous. Conservation experts also worry about the impact on already troubled animals.
One approach to susceptibility studies is to look at the animal’s genome and see which one has a genetic sequence that encodes a protein on a cell called an ACE2 receptor, which allows the virus to attach. A team of researchers studied the genomes of more than 400 animal species. Another group did a similar study of primates, which are often infected with a human respiratory virus.
“One of the prerequisites for this research is that we think the great ape will be very dangerous because of its close relationship with humans, genetically,” Amanda D. Melin, an anthropologist. at the University of Calgary and author of primate studies.
However, she added, she and her colleagues also wanted to consider “all other primates and their potential dangers.” In addition to investigating the genome, the team also performed computer modeling of the interaction of the viral mutant protein with different ACE2 receptors.
The findings of both articles reinforce each other, revealing the old world monkey and all the apes at the highest risk. Both articles were released as unequaled research earlier this year.
Dr. Melin and her colleagues spoke to representatives of wildlife and zoo reserves about the need for caution. Many of these facilities have increased the restrictions on human-primate interactions.
Zarin Machanda, of Tufts University, who studies chimpanzee behavior at the Kibale Chimp Project in Uganda, says the reserve has strengthened its pandemic safety precautions.
“We are always cautious about respiratory viruses, because they are the leading cause of death in Kibale chimpanzees,” she said. Even the common cold in humans can be fatal.
The chimpanzees have suffered from outbreaks of other coronaviruses. Normally, humans in Kibale maintain a minimum distance of twenty feet from chimpanzees; has been raised 30 feet or more. The local laborers have stayed in the reserve, instead of going back to work in their communities. And the project has reduced field time. All of these measures are directed by the Ugandan government.
Tony Goldberg, a veterinarian at the University of Wisconsin, Madison, and head of the Kibale EcoHealth Project, says he witnessed the devastation caused by respiratory ailments in chimpanzees. A fatal outbreak in 2013 in the reserve turned out to be caused by the human virusushinovirus C, the most common cause of the common cold worldwide. Until then, it was never seen in chimpanzees.
“The last thing we need is that SARS-CoV-2 moves into an animal reservoir from which it can reappear,” Dr. Goldberg said.
Other researchers are studying species from Beluga whales to deer rats for signs of the coronavirus. “So far, we have tested 282 animal samples,” said Kate Sawatzki, animal surveillance coordinator for a test project on pets and other animals at Tufts University’s Cummings School of Animal Health. wildlife from 22 species, mainly bats in New England rehabilitation facilities. , and we are happy to report that none of these have been satisfactory. “
They also examined 538 domestic animals, including from households with someone infected with Covid-19, and no children showed any signs of the virus being active. However, Dr. Sawatzki said the lab also performed blood tests for antibodies, which showed the exposure and there they found antibodies, as is common in humans. Pets appear to be infected but do not get sick or transmit the virus.
To date, weasels in Denmark are the only known cases of a virus that infects animals, mutates and transmits it back to humans. Emma Hodcroft of the University of Basel, Switzerland, has tracked different mutant versions of the coronavirus as it spreads across Europe and looked at scientific information published by the Danish medical authority. She said she welcomed the government’s decision to act quickly and destroy weasels: “Many countries have hesitated and waited before acting, and that can be extremely unfavorable in the face of SARS-CoV-2, as we see it. “
But she disapproved of the way the information was released, especially during Wednesday’s government press conference, which warned of a serious threat to potential vaccines to humans but did not release. details of the concern. “Science’s communication could be much clearer and make the world less anxious,” said Dr. Hodcroft.