China has banned the trade of wild animals. The coronavirus likely jumped to people in a wet market where meat, seafood, and live animals were sold.
- The Huanan Seafood Wholesale Market was once thought to have been the starting point of the novel coronavirus outbreak that originated in Wuhan, China. It was shuttered January 1.
- Coronaviruses are zoonotic diseases, meaning they jump from animals to humans.
- At many wet markets, meat, poultry, and seafood are sold alongside live animals for consumption.
- On February 24, China's top legislature banned the buying, selling, and eating of wildlife.
- These photos show what these Chinese markets looked like over the last 20 years.
- Visit Business Insider's homepage for more stories.
The novel coronavirus and the SARS outbreak of 2003 have two things in common: Both are from the coronavirus family, and both have been associated with animals commonly sold in "wet markets."
Historically at such markets, outdoor stalls are squeezed together to form narrow lanes, where locals and visitors shop for cuts of meat and ripe produce. A stall selling caged chickens may abut a butcher counter, where meat is chopped as nearby dogs watch hungrily. Some vendors hock hares, while seafood stalls display glistening fish and shrimp.
Wet markets put people and live and dead animals — dogs, chickens, pigs, snakes, civets, and more — in constant close contact. That makes it easy for zoonotic diseases to jump from animals to humans.
"Poorly regulated, live-animal markets mixed with illegal wildlife trade offer a unique opportunity for viruses to spill over from wildlife hosts into the human population," the Wildlife Conservation Society said in a statement.
The market where the current outbreak may have started, the Huanan Seafood Wholesale Market in Wuhan, was shuttered January 1. Wuhan authorities banned the trade of live animals at all wet markets there soon after, and China announced a temporary national ban on the buying, selling, and transportation of wild animals in markets, restaurants, and online marketplaces across the country as well. However, research since then has indicated the market may not have been the origin of the outbreak.
That ban is now permanent. Farms that breed and transport wildlife to wet markets were also quarantined and shut down.
Here's what Chinese wet markets looked like over the years before these new policies went into effect.
Reports indicate that before the Huanan market closed, vendors there sold seafood, meat, and live animals, including chickens, donkeys, sheep, pigs, foxes, badgers, bamboo rats, hedgehogs, and snakes. This image is of a Chinese wet market from 2007.
Wet markets like Huanan are common in China. They're called wet markets because vendors often slaughter animals in front of customers.
"That means there's a lot of skinning of dead animals in front of shoppers and, as a result, aerosolizing of all sorts of things," Emily Landon, an infectious-disease specialist at University of Chicago Medicine, wrote in an article.
A January report challenged the idea that virus emerged in the Huanan wet market, however.
What's more, 13 of 41 coronavirus cases had no link to the Huanan marketplace, the researchers said. More research is needed to pinpoint the outbreak's starting point with certainty.
Some experts have applauded the permanent ban. "The government has signaled that it wants to take immediate action to prevent any future outbreaks of diseases that spread from animals to humans," Li Zhang, a conservation biologist at Beijing Normal University, told Nature.
Li added that wildlife trade and consumption was both a direct threat to animals and a major public-health risk.
The close proximity of shoppers to stall vendors and live and dead animals in wet markets has made them breeding grounds for zoonotic diseases in the past.
Three-quarters of new or emerging infectious diseases in people come from animals, according to the Centers for Disease Control and Prevention.
SARS originated in wet markets in the province of Guangdong. It killed 774 people across 29 countries from 2002 to 2003.
In the case of SARS, humans caught the virus from weasel-like mammals called masked palm civets. This image is from 2004,
But the civets weren't the original hosts of the disease.
Researchers figured out that SARS originally came from a population of bats in China's Yunnan province.
"Coronaviruses like SARS circulate in bats, and every so often they get introduced into the human population," Vincent Munster, a virologist at the Rocky Mountain Laboratories, told Business Insider.
Bats can pass along viruses in their poop: If they drop feces onto a piece of fruit that a civet then eats, the civet can become a disease carrier.
Bats and birds are considered reservoir species for viruses with pandemic potential, according to Bart Haagmans, a virologist at the Erasmus Medical Center in Rotterdam, Netherlands.
"Because these viruses have not been circulating in humans before, specific immunity to these viruses is absent in humans," Haagmans told Business Insider.
The most likely intermediary-species candidates are pigs, civets, and pangolins.
A group of researchers from South China Agricultural University found that samples of coronaviruses taken from wild pangolins and those from infected coronavirus patients were 99% identical. But this research has yet to be published or confirmed by other experts.
The pangolin is an endangered mammal that resembles a scaly anteater. The trade and consumption of pangolins is illegal under China's Wildlife Protection Law, but they are still known to be roasted and eaten in China, Vietnam, and parts of West Africa. Pangolin scales have also been used in traditional Chinese medicine.
A group of scientists who edit the Journal of Medical Virology initially suggested the culprit could be the Chinese cobra, but many other scientists say that's highly improbable.
Cui Jie, a virologist who was on a team that identified SARS-related viruses in bats in 2017, told Nature that this coronavirus strain was clearly a "mammalian virus."
"They have no evidence snakes can be infected by this new coronavirus and serve as a host for it," Paulo Eduardo Brandão, a virologist at the University of São Paulo who is investigating whether coronaviruses can infect snakes, told Nature.
The H7N9 and H5N9 bird flus — also zoonotic viruses — were most likely transmitted to humans in wet markets, too.
According to the World Health Organization, people caught those bird flus via direct contact with infected poultry in China. The diseases killed 1,000 people globally.
"There have been plenty of eminent epidemiologists predicting 'pandemic X' for a number of years now," Adrian Hyzler, the chief medical officer at Healix International, told Business Insider.
These pandemics "are more likely to originate in the Far East because of the close contact with live animals [and] the density of the population," Hyzler added. His firm offers risk-management solutions for global travelers.