An international team of scientists studied data collected from a live food market in Wuhan, China, where the COVID-19 disease broke out. Genetic data showed a link between COVID-19 and raccoon dogs. Researchers argue that infected animals sold on the market may be the main source of the coronavirus pandemic.
China is among the countries famous for their animal markets. However, many markets were closed after the start of the pandemic. One of them is the Huanan seafood market. Scientists had previously found both coronavirus and human DNA in swab samples collected from stalls in the Huanan seafood market. These findings were published last year, and Chinese researchers suggested that there was no animal DNA in the samples. The international scientific team refuted this claim.
The researchers analyzed the gene sequences in the samples and found that the COVID-19 positive samples were rich in DNA from raccoon dogs. DNA traces of other mammals, including civets, were also present in COVID-positive samples.
These new findings do not prove that raccoon dogs or other animals infected with COVID-19 triggered the outbreak, but do make it more likely. Meanwhile, the international team of scientists presented the study to an expert group at the World Health Organization on Tuesday.
"The data point to a market origin," evolutionary biologist Prof Kristian Andersen from Scripps Research in California, USA, told Science. Andersen attended a meeting of the WHO's scientific advisory group on the origins of new pathogens and is working on the data.
According to the theory of a large group of scientists, the new type of coronavirus first appeared in animals and spread to humans through market contamination. Another common theory is that the Sars-Cov-2 virus that causes COVID-19 disease leaked from the Wuhan Institute of Virology, where researchers are studying similar pathogens. There is no conclusive evidence for either theory.
These latest genetic data also do not prove that raccoon dogs or other mammals have been infected with the coronavirus and spread in the market. If animals are infected, they may have contracted the virus from infected humans. But the findings suggest that the cause may be an infected animal and ultimately the illegal wildlife trade.
While scientists expect the debate to continue, there is confusion as to why the Chinese team did not publish the genetic data earlier. George Gao, former head of the Chinese Centers for Disease Control and Prevention, who was a member of the team, said there was "nothing new" in DNA sequences. It is not clear why the data was later pulled from the Gisaid site. Débarre stated that they are working on the findings but will answer questions once they are made public.
Virologist and senior group leader at the Francis Crick Institute in England, Dr. Commenting on the study, Jonathan Stoye said: "The finding of Sars-CoV-2-infected raccoon dogs strengthens the possibility that coronavirus-infected livestock was an important link in the sequence of events leading up to the COVID-19 pandemic. However, it does not disprove the laboratory leak theories."
Meanwhile, World Health Organization Director of Emergencies Michael Ryan said the COVID-19 outbreak could calm down this year, posing a similar risk to the flu. But he also warned that COVID-19 can still lead to the death of people.