“The penalties for perpetrators can be severe,” says Zhou Zhaomin, policy expert on China’s wildlife trade at China West Normal University in Nanchong. Those who trade in protected species can face up to 15 years in prison, and smuggling sufficient numbers to or from China could result in life imprisonment.
But the implementation of the law was poor. Several researchers told MIT Technology Review that it was “an open secret” that illegal wildlife trafficking was widespread in China.
In fact, between 2017 and 2019, Zhou and his colleagues conducted a survey that found that a total of nearly 48,000 wildlife of 38 species were sold in four markets in Wuhan, including Huanan, almost all of which were sold live, caged and stacked cramped , unsanitary conditions perfect for virus transmission. Animals – either wild-caught or bred non-domesticated species – include species susceptible to both SARS-CoV-1 and SARS-CoV-2, such as civets, minks, badgers, and raccoon dogs.
This study, published in June in Scientific reports, found that all of the wildlife trafficking the researchers surveyed was illegal. Many sellers sold protected species; no one has posted the necessary certificates stating where the animals came from or that they were disease free.
This means that once Huanan were involved in early Covid-19 cases, vendors selling live mammals most likely illegally would run away to avoid incarceration, while law enforcement is unlikely to admit that such activity ever existed. In light of this, it was not surprising that the Chinese authorities found no evidence of live animal sales in the Huanan market, says Harvard’s Hanage.
Restrictions on wildlife trade were minimal after SARS, giving scientists almost unlimited access to animals and traders in Guangdong’s wet markets – but even that was insufficient to determine the source of SARS. While they quickly discovered viruses in civets, badgers and raccoon dogs that were more than 99% identical to SARS-CoV-1, subsequent studies did not reveal widespread spread of the virus, either in the wild or under breeding conditions. A prevalent view is that civets got the virus in-trade, most likely from bats that were bought and sold at the same time.
Today, 18 years later, the situation is strikingly similar. SARS-CoV-2 does not appear to be widespread in animals. None of the roughly 80,000 samples tested by the World Health Organization’s Chinese team to hunt down the origins of the pandemic – including prime suspects such as pangolins, civets, badgers and bamboo rats – contained the virus.
Even so, many scientists still lean strongly on the theory that wet markets played a crucial role in triggering Covid-19. Although all eyes are on Yunnan and other parts of Southeast Asia as the most likely source of the pandemic, Hanage says “It’s not crazy” to suggest that Hubei Province in Wuhan may have been the location where SARS-CoV-2 was found occurred naturally.
In fact, scientists at the Wuhan Institute of Virology have found SARS-like coronaviruses in bats in Hubei. Although they haven’t systematically tested farm animals for coronavirus infections across the province, a little-known study after SARS found that the seven civets they tested on a farm in the province in 2004 all did. Relatives of SARS-CoV-1 were infected. Several research teams in China and the US are trying to find out where the animals got the virus from, whether coronavirus infection is more common in civet cats than previously thought and what impact this could have on our understanding of the origins of Covid-19.
Constant overflow
But with no evidence of an animal infected with a coronavirus that is more than 99% identical to SARS-CoV-2, some scientists continue to argue against its natural origin.
One such critic is Alina Chan, a molecular biologist at the Broad Institute of MIT and Harvard (this publication is owned by MIT, but editorially independent). The key question, she said in a recent webinar organized by Science magazine, is how the virus got to Wuhan from caves more than a thousand miles away in China or other parts of Southeast Asia. “There is a very strong leadership of scientists in Wuhan who go to these places where they are [knew] They would find SARS virus and take them to Wuhan City like thousands of kilometers, ”she said. However, there is no evidence of such wildlife trafficking routes, she added.
Such a lack of clarity plagues the origins of SARS, says Linfa Wang, director of the emerging infectious diseases program at Duke National University in Singapore. The cave that spawned SARS-CoV-1’s closest bat relative is nearly 1,000 miles from the Guangdong market, where the first SARS cases arose – similar to the distance between Wuhan and the place where one of the closest Bat relative of SARS-CoV -2 was discovered.
And it is becoming increasingly clear that people who have close contact with wildlife are infected with coronavirus much more often than previously thought.
“[Huanan] is much more likely than other scenarios based on what we now know. “
Michael Worobey
Studies show that up to 4% of people who live near bats and work closely with wildlife in southern China are infected with deadly animal-borne viruses, including coronaviruses. A Laotian and French team that discovered SARS-CoV-2’s closest relatives found that one in five bat handlers in Laos had antibodies to this coronavirus.
The majority of these spillover infections will die off on their own, researchers say. In a study published in Science in April, Worobey and his colleagues use computer simulations to show that an urban environment is crucial for the spread of SARS-CoV-2 to trigger major epidemics – without it it would die out very quickly.
“It is a hundred, if not a thousand times more likely” that a wildlife trafficker who was exposed to a SARS-CoV-2 precursor – either from bats or another species – brought the infection to Huanan than a researcher who passed samples Collecting bats came back to Wuhan with the pathogen and then brought it to Huanan, says Wang.
Worobey agrees. Based on a lot of evidence, he is now convinced that the connection between the pandemic and the Huanan market is not only real, but that a SARS-CoV-2 precursor has jumped from an animal to humans. “That’s far more likely than any other scenario we know today,” he says.
Preliminary findings from ongoing work by his group and others will help strengthen the case, he adds, “They’re all pointing in the same direction.”
Coverage for this article was supported by a grant from the Pulitzer Center.
