- Helen Briggs
- BBC environmental correspondent
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29 minutes ago
Image source, Getty Images
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The stoat plague is the “overflow” of the human pandemic.
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The mutation of the corona virus has triggered the culling of millions of minks in Denmark.
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Some parts of the country imposed lockdowns after Danish authorities discovered genetic changes that they said could impact the effectiveness of a future Covid-19 vaccine.
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More than 200 people have been infected with the coronavirus strain found in mink.
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Britain has banned all visits from Denmark, amid concerns over a new strain of the virus.
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Danish scientists are particularly concerned about one type of virus related to mink, which was found in 12 people. Scientists say the virus is less sensitive to the body’s antibodies. This raises concerns about vaccine development.
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The World Health Organization (WHO) said the report was worrying, but that further study was needed to understand the implications of treatments and vaccines.
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“We need to wait and see what the implications are, but I don’t think we should come to any conclusions about whether this particular mutation will impact vaccine efficacy,” said chief scientist, Soumya Swaminathan.
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Image source, Getty Images
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Authorities arrive at the mink farm to exterminate the animals.
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The coronavirus, like all viruses in general, mutates over time, and there is no evidence that any of the mutations found in Denmark increased the level of harm to humans.
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Marisa Peyre, an epidemiologist with the French research institute Cirad, said the developments were “worrying”, but we don’t yet know the full picture.
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“Every time the virus spreads between animals, it will change, and if too much changes from what is circulating in humans today, it may mean that any vaccine or treatment that is about to be produced may not work as well as it should,” he explained.
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Image source, Getty Images
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Stoats, like its relative species, weasels, are susceptible to respiratory viruses.
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What’s happening now is a very unusual series of events: in which a virus that originally came from a wild animal – possibly a bat – passed to humans, possibly through an unknown animal host and triggering a pandemic.
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The stoats raised in large numbers on mink farms have contracted the coronavirus from infected workers. And, in a small number of cases, the virus has “re-spread” from mink to humans, bringing about genetic changes in the process.
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The mutations in several strains related to mink involve spurting viral proteins, the part of which several vaccines are being developed.
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“If the mutation is in a particular protein that vaccine developers are currently targeting to trigger an immune response in humans, that means, a new strain of mink virus that jumps to humans, even with vaccination, humans will start spreading it and the vaccine won’t be able to protect,” Peyre told BBC News.
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More than 50 million minks are bred each year for their fur, mainly in China, Denmark, the Netherlands and Poland. Outbreaks have been reported on mink farms in the Netherlands, Denmark, Spain, Sweden, Italy and the United States, and millions of animals have had to be culled.
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Image source, Getty Images
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Millions of stoats culled in Denmark.
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Stoats, like their close relative, the civet, are known to be susceptible to the coronavirus. And, like humans, they can experience a variety of symptoms, from showing no signs of illness at all to severe symptoms, such as pneumonia.
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Scientists suspect the virus spreads in mink farms through splashes, on feed or bedding, or in dust containing dung.
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Mink has been infected with the virus from humans, but genetic investigators’ investigations show that in a small number of cases the virus also appears to have spread the other way around, with the virus that passes from mink back to humans.
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Stoats have become a “reservoir of viruses” and surveillance is needed on other wild and domestic animals that may be susceptible, said Professor Joanne Santini of University College London.
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“Mink is extreme, but it could be out there and unknown, and that is something we need to check,” he told BBC News.
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“What we do know is that minks get the virus from humans; they can get infected and they pass it among themselves and also back to humans.”
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Scientists in Denmark are carrying out genetic studies on the strains found in mink, and genetic data has been shared with other researchers, to allow further investigation.
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“We need to find out where this mutation is and we need to see what effect it has on viral transmission and how contagious the mutation is, because if it changes and becomes more contagious or has a wider host range then that’s really enough scary, but maybe not, because we don’t know, “said Santini.
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Some scientists have called for new restrictions on mink production, saying mink farming is “hindering our response and recovery from the pandemic.”
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In a recent letter to jurnal Science, three scientists, from Denmark, China and Malaysia, wrote: “It is imperative to monitor, limit and – where possible – ban mink production.”
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The World Health Organization has called on all countries to increase surveillance and tighten biosafety measures around mink farming.
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