Although the COVID-19 pandemic has been rocking the world for the last three years causing untold suffering, there are still many things to consider about what started it all. The scientific evidence thus far suggests that SARS-CoV-2, the virus that causes COVID-19, likely resulted from viral evolution in nature and jumped to people through some unidentified animal host.
Some of the proposed candidate animals for the zoonotic origin of SARS-CoV-2 include bats, civets, and other exotic animals sold at the Huanan Seafood Wholesale Market, the suspected epicenter of the pandemic.
But very recently, an international group of scientists has crunched new genetic data and revealed a new likely viral host candidate — a strange and rather obscure animal known as the raccoon dog.
What is a raccoon dog?
The raccoon dog, also known as the mangy or tanuki, is a canid native to East Asia, particularly Japan, China, Vietnam, and Korea. However, thousands were commercially bred for their fur in the former Soviet Union, and now the raccoon dog has become quite widespread in northern Europe as well, where it is considered an invasive species and pest.
Despite its name due to its raccoon-like face markings, it is not closely related to raccoons or even dogs, but rather to foxes belonging to its own distinct Nyctereutes genus.
The raccoon dog is a small to medium-sized mammal, ranging from 45 to 65 cm in length and 4 to 10 kg in weight. It has a distinctive appearance, with short legs, a round face, a thick fur coat, and a bushy tail. Its fur is often used for clothing and accessories, particularly in Japan, where the raccoon dog is a popular symbol of luck and prosperity.
Scientists estimate that less than 5% of the ~5,000 known mammal species in the world practice any form of monogamy whatsoever — but the raccoon dog is one of them, with adults expected to form a breeding pair that mates for life. Another interesting fact about these peculiar mammals is that Raccoon dogs are the only canids (dog family) that hibernate.
Some might look at these creatures and think about keeping them as pets, just like some do with raccoons. That’s a really bad idea, though. Raccoon dogs are wild animals and require very large home ranges, which makes them ill-suited to keeping in an enclosure. You definitely don’t want to keep one in the household as they are notoriously smelly, releasing putrid chemicals that they use to communicate with one another. That’s not to mention the fact that it is highly illegal to own one as a pet as they threaten the local native wildlife.
Nevertheless, these obvious drawbacks don’t stop some people from keeping raccoon dogs as pets, with potentially disastrous consequences for all. In 2019, a pair of raccoon dogs escaped from a British home where they were kept as pets and subsequently wreaked havoc in a small English village, harassing small livestock and pet animals.
However, it’s not companionship that makes most people seek out raccoon dogs, but rather their fur. Millions are killed in China every year for their highly prized fur. Visitors of the crowded wet markets that are very common across rural China will undoubtedly come across raccoon dogs kept in small cages, often housed with other wild animals. This is a prime breeding ground for infections and diseases, which brings us to a recent study that made the news this week.
What’s the connection of the raccoon dog to COVID-19?
An international team of researchers analyzed gene sequences from swab samples collected from stalls at the Huana seafood market in Wuhan, China. They found that many of the COVID-positive samples contained DNA from raccoon dogs. DNA traces belonging to other mammals, including civets, were also found in such coronavirus-containing samples.
Speaking to the press during an expert group meeting at the World Health Organization (WHO), the authors of the new study note that their findings don’t single out raccoon dogs as the definite source of SARS-CoV-2, but solidify the narrative of a market origin of the virus. Some suggest that the pandemic-causing coronavirus is actually a lab leak from the nearby Wuhan Institute of Virology, but — although a possibility — this is less plausible than a zoonotic origin which genetic studies have highlighted.
However, at the moment, neither of the two theories can be substantiated with hard evidence and that may never happen, especially given the opaque nature of investigations made thus far and the Chinese government’s efforts to block any meaningful inquiries on the ground.
“These data could have and should have been shared three years ago,” said the World Health Organization’s director-general Tedros Adhanom Ghebreyesus. “We continue to call on China to be transparent in sharing data and to conduct the necessary investigations and share the results. Understanding how the pandemic began remains both a moral and scientific imperative.”
“These data do not provide a definitive answer to the question of how the pandemic began, but every piece of data is important in moving us closer to that answer,” said the WHO chief.
The raccoon dog gene sequences were discovered by Florence Débarre, an evolutionary biologist at the French National Center for Scientific Research. She noticed the genetic material from the fox-like canids inside a larger gene sequence of the virus that researchers in China from the Chinese Center for Disease Control and Prevention had uploaded to the public genomic database called GISAID. Although this file was subsequently taken down, Débarre had access to a copy.
When the WHO reached out to the Chinese research team regarding the disappearance of the genetic data, they were told that the data had been restricted, pending an update of their research paper.
The new findings are consistent with the notion that the pandemic-causing virus emerged at the Wuhan wet market after it jumped from an animal to humans. However, the evidence that this jump occurred from raccoon dogs is circumstantial, so it should be taken with a grain of salt.
“We need to make clear that the virus has not been identified in an animal in the market or in animal samples from the market, nor have we actually found the animals that infected humans,” said WHO’s COVID-19 technical lead Maria Van Kerkhove at the press briefing.
“What this does is it provides clues to help us understand what may have happened.”
