China cracked down on the sale of exotic species after an outbreak of a new virus in 2002 was traced to food markets selling live animals.
The germ was a coronavirus later named SARS. The ban was soon lifted, and the animals reappeared. Now another coronavirus is spreading through China, so far killing more than 1,000 people and sickening more than 42,000 — five times more than SARS.
The likely origin? The same type of market.
"During SARS epidemic, we saw some bans," said Jinfeng Zhou of the China Biodiversity Conservation and Green Development Foundation, but added that after the outbreak had been contained, a "large black market" was quickly re-emerging.
With millions of people under lockdown in a dozen Chinese cities, the new outbreak is prompting calls to permanently ban the sale of wildlife, which many say is being fueled by a limited group of wealthy people who consider the animals delicacies.
The spreading illness also serves as a grim reminder that how animals are handled anywhere can pose a risk to people everywhere.
SARS and the current outbreak of COVID-19 are not the only diseases in people traced back to animals. The killing and sale of what is known as bushmeat in Africa is thought to be a source for Ebola.
Bird flu likely came from chickens at a market in Hong Kong in 1997. Measles is believed to have evolved from a virus that infected cattle.
Scientists have not yet determined exactly how the new coronavirus first infected people. Evidence suggests it originated in bats, which infected another animal that spread it to people at a market in the southeastern city of Wuhan.
Huanan Seafood Wholesale Market advertised dozens of wild species — some likely raised on farms, others hunted — like giant salamanders, baby crocodiles and raccoon dogs.
"The perfect place really for a virus to spread, to jump from one species to another is a market place where dozens of different animals are brought together with the viruses in close contact. And of course, people in the children and the elderly people are in there and they get exposed too, " said Peter Daszak, president of EcoHealth Alliance.
Of the 33 samples from the Wuhan market that tested positive for the coronavirus, 31 were from the area where officials say wildlife booths were concentrated. Unlike with domesticated livestock like chickens and pigs, researchers say less is known about the viruses that circulate in wild animals.
The Wuhan market was also like many other "wet markets" in Asia and elsewhere, where dozens of animal species are tied up or stacked in cages. The animals are often killed on site to ensure freshness. The messy mix raises the tiny odds that a new virus will jump to people handling the animals and start to spread, experts say.
And more frequent global travel and trade means there's greater risk for outbreaks to spread.
China's taste for wildlife is relatively new, prompted by the country's economic growth,.
There are signs the Chinese government may make more lasting changes to how exotic species are raised and sold. This month, Chinese Communist Party Chairman Xi Jinping said the country should "resolutely outlaw and harshly crack down" on the illegal wildlife trade because of the public health risks it poses.
In the eastern province of Anhui, officials sealed farms breeding species like badgers and bamboo rats. In the port city of Tianjin, authorities say their crackdown on the sale of wildlife caught six traders, including three who were selling pythons and parrots.
All told, officials say about 1.5 million markets and online operators nationwide have been inspected since the outbreak began. About 3,700 have been shut down, and around 16,000 breeding sites have been cordoned off.
It's not clear how the measures will play out over time. Before the outbreak began, it was legal in China to sell 54 species like pangolins and civets — as long as they were raised on farms.
That made it difficult to distinguish between legal and illegal wildlife in wet markets, and enforcement was lax shares Jinfeng Zhou of China Biodiversity, Conservation and Green Development Foundation, an environmental group based in Beijing.
Others disagree, arguing that banning all wildlife trade is not a realistic way to reduce risk, especially in poorer regions of the world where it can be an important food source. They say better monitoring, regulation or public education may be better ways to
control the problem.
Even if China successfully regulates or bans it, the wildlife trade is likely to continue elsewhere. Recent visits to wet markets in the island of Sulawesi in Indonesia and in the coastal city of Doula in Cameroon revealed similar conditions to wet markets in China.
Vendors were slaughtering and grilling bats, dogs, rats, crocodiles and snakes, and sanitary measures were scant.
Ongoing destruction of species' habitats will likely bring people into closer contact with animals and their viruses.