Five years after the COVID-19 outbreak that laid waste to economies and freedom of movement around the world and, despite countless theories, questions about the origins of its virus largely remain without a precise answer. But there’s evidence raccoon dogs might be responsible.
As it happens, mounting evidence from over a dozen studies points to an individual, or individuals, catching the virus from a wild animal or animals at the Huanan Seafood Market in Wuhan, China, the city at the epicenter of the outbreak, according to a Nature report published on February 21.
Per Kristian Andersen, an evolutionary biologist at Scripps Research in La Jolla, California: “There is a large focus on raccoon dogs.” That said, virologist Edward Holmes at the University of Sydney, Australia, has suspected these animals all along.
Indeed, on January 21, 2020, he sent Andresen and another colleague an email in which he had bet on raccoon dogs at the Huanan market, which he had seen there during his trip to Wuhan in 2014.
Why raccoon dogs?
The reason why many scientists suspect raccoon dogs is their probable connection in passing another, related, virus to people. Specifically, in 2003, researchers isolated close matches of the virus causing severe acute respiratory syndrome (SARS) in several civets and a raccoon dog at a live-animal market in Guangdong, China.
This has prompted scientists in Germany to investigate the animals’ susceptibility to SARS-CoV-2, upon which they found that raccoon dogs (sold at markets in Wuhan for their fur and as food) can become infected by the virus and pass on the infection to other animals without getting very sick themselves.
Furthermore, studies by Holmes and his colleagues have demonstrated that farmed and wild raccoon dogs in China are susceptible to infections with many viruses that can jump between species, and Holmes has said that they “are very common viral hosts.”
It didn’t help that, according to monthly surveys across four markets in Wuhan between May 2017 and November 2019, an average of 38 raccoon dogs were sold at these markets every month, the most-sold species being Amur hedgehog at an average of 332 a month. Masked palm civets, hog badgers, Chinese bamboo rats, and Malayan porcupines were also regular offerings.
In 2023, more evidence came in from Chinese researchers who analyzed swabs from the Huanan market’s stalls, garbage cans, and sewage in January 2020, after it was shut down. Specifically, they found mitochondrial DNA of raccoon dogs in several swabs, including those positive for SARS-CoV-2.
Was it definitely raccoon dogs?
The science community is still deliberating. According to Michael Worobey, an evolutionary biologist at the University of Arizona in Tucson, raccoon dogs do top the list of possible suspects, but it’s because they have been the subject of more studies than other animals, including those also present at the market, so there are other candidates.
Echoing his view, Marion Koopmans, a virologist at Erasmus MC in Rotterdam, the Netherlands, argues “We have to be modest about our ability to predict which animal species” started the COVID-19 pandemic. Considering how politicized the whole issue has been, this does sound sensible.
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