The Danish government's decision this week to kill millions of minks over coronavirus concerns, wiping out a large national industry, has put the spotlight on simmering concerns of scientists and conservationists about animal susceptibility to the pandemic virus and what infections Animals could mean for humans.
The most worrying possibility is that the virus will mutate in animals and become more transmissible or dangerous to humans. In Denmark, the virus has shifted from humans to mink and back to humans and has mutated in the process. Minks are the only animals known to have passed the coronavirus on to humans, with the exception of the initial spillover event of an unknown species. Other animals, such as cats and dogs, have been infected through exposure to humans, but are not There are known cases of people becoming infected from exposure to their pets
The versions of the virus that mutate in the mink and spread to humans are non-communicable or cause more serious illnesses in humans. One of the variants found so far in 12 people, however, reacted less to antibodies in laboratory tests. The Danish health authorities feared that the effectiveness of vaccines being developed for this variant could be affected and decided to take all possible measures to stop its spread. This involved killing all of the country's mink and effectively locking down the northern part of the country where the mutated virus was found. The United Kingdom has banned travelers from Denmark who are not British citizens.
The World Health Organization and scientists outside Denmark have stated that there is no evidence yet that this variant will affect vaccines. However, you have not criticized Denmark's decision to kill its mink population.
Minks aren't the only animals that can be infected with the coronavirus. Dogs, cats, tigers, hamsters, monkeys, ferrets and genetically engineered mice were also infected.
Dogs and cats, including tigers, appear to have few adverse effects. The other animals used in laboratory experiments showed different responses. However, farmed mink has died in large numbers in Europe and the United States, possibly due in part to the overcrowded conditions on these ranches that could increase exposure.
However, public health experts fear that any infectious species could become a reservoir that would allow the virus to reappear and infect humans at any time. The virus would likely mutate in other animal species, as has been shown in mink. While most of the mutations are likely harmless, SARS-CoV-2 could potentially recombine with another coronavirus and become more dangerous. Conservation experts also worry about the impact on species that are already in trouble.
One approach to studying susceptibility has been to examine the genomes of animals and determine which have a genetic sequence that codes for a protein on cells called the ACE2 receptor that allows the virus to lock itself in. A team of researchers examined the genome of more than 400 animals. Another group did a similar study using primates, which are commonly infected with human respiratory viruses.
"One of the pre-requisites for this research was that we believed that great apes are very vulnerable because of their close genetic relationship with humans," said Amanda D. Melin, anthropologist at the University of Calgary and author of the primate study.
However, she and her colleagues also wanted to consider “all other primates and their potential risk”. In addition to studying genomes, the team also performed computer models of the interaction of the virus spike protein with various ACE2 receptors.
The results of both papers reinforced each other and showed that monkeys of the ancient world and all apes were most at risk. Both articles were published as non-peer-reviewed studies earlier this year.
Dr. Melin and her colleagues spoke to representatives from nature reserves and zoos about the need to exercise caution. Many of these facilities have increased restrictions on human-primate interaction.
Zarin Machanda of Tufts University, who studies chimpanzee behavior at the Kibale Chimpanzee Project in Uganda, said the reserve has increased its security measures due to the pandemic.
"We are always careful with respiratory viruses," she said, because such viruses are the leading cause of death among chimpanzees in Kibale. Even the human cold can be fatal.
Chimpanzees have suffered from other coronavirus outbreaks. Typically, the people of Kibale keep a minimum of two dozen feet from chimpanzees. that was increased to 30 feet or more. Local workers have stayed in the reserve instead of commuting back and forth to their communities. And the project reduced the hours spent on field studies. All of these measures were led by the Ugandan government.
Tony Goldberg, a veterinarian at the University of Wisconsin, Madison and leader of the Kibale EcoHealth project, said he saw the havoc caused by respiratory disease in chimpanzees. A fatal outbreak in the reserve in 2013 was the result of human rhinovirus C, the leading cause of common colds worldwide. Until then, it had never been seen in chimpanzees.
"The last thing we need is for SARS-CoV-2 to get into an animal reservoir from which it can escape," said Dr. Goldberg.
Other researchers are examining species from beluga whales to deer mice for signs of the coronavirus. Kate Sawatzki, the Animal Welfare Coordinator for a Pet and Other Animal Testing Project at Tufts University's Cummings School of Veterinary Medicine, said, “To date, we've tested 282 wildlife samples from 22 species, mostly bats, in rehabilitation facilities in New England, and we look forward to having you to be able to communicate that none was positive. "
They also tested 538 pets, including those from households with people with Covid-19, and none showed signs of an active virus. Dr. However, Sawatzki said the lab also did blood tests for antibodies that showed exposure, and that's where they found antibodies, as is common in humans. The pets appeared to get infected but not get sick or pass the virus on.
So far, the mink in Denmark is the only known case in which the virus infects an animal, mutates and is transmitted back to humans. Emma Hodcroft of the University of Basel in Switzerland is tracking various mutated versions of the coronavirus as it has spread in Europe and has reviewed the scientific information released by the Danish health authorities. She said she welcomed the government's decision to act quickly and weed out the mink: "Many countries have hesitated and waited before acting and it can be incredibly damaging in the face of SARS-CoV-2, as we can see. "
However, she disagreed with the way the information was made public, particularly at the government press conference on Wednesday that warned of a serious threat to potential human vaccines but did not provide details for the concern. "The communication of science could have been much clearer and less worrying around the world," said Dr. Hodcroft.