Yes, You Can Get COVID-19 From Animals
What we can learn from the first identified animal-human transmission
While the world is coping with a pandemic, a big question mark remains surrounding the origin of SARS-CoV-2. This virus infected at least one person at a wildlife and food market in Wuhan, China, but it is still unclear which species transmitted it. Many animals have been pointed to as culprits, such as the pangolin and bat, but recent research defended their innocence. Besides this one transmission, it was previously assumed you can only be infected by other people. However, shocking news was announced last week. There is proof minks have transmitted SARS-CoV-2 to workers in several Dutch mink farms. As more and more species test positive for the virus, an attention shift from humans to farm animals and pets is needed for further transmission prevention.
Disclaimer: when writing ‘animals’, I am talking about non-human animals.
The Animal It’s All About
Minks are semiaquatic mammals that belong to the same family as weasels, otters and ferrets. They are generally bred for producing furs in mink farms, and less often their body fat is used in beauty products and medicine. The animals are kept in battery cages on the farms that make movement impossible and frequently lead to mental psychoses in the minks. These ‘stereotypies’ can be described as repetitive and abnormal behaviors occurring as a result of imprisonment. It is one of many reasons mink farms have been a focus of animal rights activism. China and Denmark produce most mink fur. The Netherlands holds a third spot, with around 160 of these farms, each containing on average 5000 minks. Not all the produced fur is used by Dutch people: most of it is shipped to Russia, the United States, Canada and China.
An Important Discovery
It is in one of these Dutch mink farms that transmission from animal to human has been detected. Initially, the farmers started to notice behavioral changes (mostly breathing difficulties) in their minks. This asked for screenings, and so far on eight separate farm locations, minks have tested positive for SARS-CoV-2. The farmers were, however, told not to worry too much, since the chance of animals infecting humans was believed to be very small. Some of the workers also tested positive for the virus, so most probably, they had transmitted it to the minks. But new research turned the story upside-down: the workers had been infected by minks. This is unique: nowhere in the world has such a transmission from animal to human been documented.
(Un)Certainty In The Transmission Chain
How can we be so sure of this transmission? Well, every viral type has a unique code. A virus can mutate while undergoing an arms race with its host. Its ‘suction cup’ protein parts that attach to host cell receptors also vary per transmission type, since these receptors are unique. Thus, a viral ‘genetic code’ can say something about the transmission that has preceded. This means SARS-CoV-2 is actually an umbrella term for one virus in many different forms. In this case, farm workers as well as minks were tested for the virus. A similar strain of SARS-CoV-2 was found in both, and confirmed mink-to-human transmission. However, it remains unclear how the minks themselves were infected. It seems improbable to have been humans, since no one else in the neighborhood tested positive except for these workers. The most plausible culprits are actually cats. Cats have already tested positive for the virus in other locations, and many roamed on and around these farm sites. On one of the Dutch farms, 7 out of 24 cats carried antibodies against SARS-CoV-2, making this hypothesis even more likely.
Mink Farms: Present and Future
Luckily, risk of transmission from the minks is still ‘negligible’ compared to human transmission. Moreover, now that we know it does happen occasionally, measures can be taken to reduce chances further. Mostly, this means treating minks as we treat people nowadays. Employees are required to wear protective equipment and advised to keep 1,5 meters distance from them. Visitors are no longer allowed at any Dutch mink farm. In The Netherlands, these sites already had to close in 2023 at the latest, but animal rights activists and certain political parties now argue for closing the farms earlier. However, this is not happening yet, as the danger is considered ‘manageable’. In the mean time, all Dutch mink farms are being monitored. Screening for the virus in humans, cats and minks is mandatory. Minks and cats are not permitted to leave sites, further preventing spread.
*update 3/6/19: the Dutch government is as of now actually shutting down farms on which minks test positive*
The Role of Animals in Viral Transmission
Many questions have been posed concerning animal to human transmission. Which species was the first to infect a human? Are other animals susceptible? Can these also infect humans? Thanks to studies, more has become clear. Some species are believed not to be infectious: amongst these are rats, mice, pigs, chickens and ducks. In others, antibodies have actually been found, meaning they are susceptible. Examples are dogs, rabbits, ferrets, cats, and of course, minks. Moreover, eight big cats have tested positive for the virus at the Bronx Zoo in New York. Dogs are also susceptible, although less than cats. Presumably, all of these animals can be asymptomatic like us, thus not showing any symptoms while still being able to transmit the virus. This makes monitoring and containment much harder. And, as now has become clear, some animals can infect humans too. In conclusion, although animal to human transmission is uncommon, it does happen occasionally. Therefore, pets and farm animals are advised to be treated as family members. When such a member is sick or carries the virus, they should steer clear from interaction with others as much as possible.
Which Animal Is To Blame?
There is a lot we still do not know about SARS-CoV-2, specifically concerning the role of animals in transmission. What is evident, however, is that wildlife and pets can carry the disease, and that some can even transmit the pathogen to us. What we also know, as I mentioned in an earlier post, is that coronaviruses such as SARS-CoV, MERS-CoV and now SARS-CoV-2 have all been transmitted because of increasing exposure to wildlife. Human population growth brings us further in contact with species’ natural habitats. Wildlife exploitation as well as trade markets all contribute to the possibility of viral outbreaks. Minimizing all these factors could reduce transmission risks and prevent future outbreaks. Maybe we should stop pointing fingers at other animals — and start blaming ourselves.
Articles used in the process of writing:
- https://www.rtlnieuws.nl/nieuws/nederland/artikel/5132781/nerts-besmet-mens-coronavirus-vragen-antwoorden
- https://www.rtlnieuws.nl/nieuws/nederland/artikel/5132266/nerts-rivm-besmetting-hugo-jonge-volksgezondheid
- https://www.rtlnieuws.nl/nieuws/nederland/artikel/5128256/corona-nerts-mens-besmet-besmettelijk-nertsenfokkerij-minkfarm
- https://nos.nl/artikel/2331784-coronavirus-vastgesteld-bij-nertsenfokkerijen-in-noord-brabant.html
- https://edition.cnn.com/2020/05/20/europe/coronavirus-mink-netherlands-testing-intl/index.html
- https://www.euronews.com/2020/05/20/coronavirus-minks-test-positive-for-covid-19-at-two-dutch-farms
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Thanks for reading! I hope you like my blog. I am Mo Schouten, a Biology student located in the Netherlands. Capturing my environment with a camera is what I love most. — — Comments as well as tips are always welcome; leave them below!
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