Researchers traced SARS to a population of horseshoe bats in China's Yunnan province. Humans caught it from weasel-like mammals called masked palm civets at a wet market in Guangdong.
From 2002 to 2003, SARS killed 774 people across 29 countries and infected more than 8,000. Patients experienced fevers, headaches, and a type of deadly pneumonia that could cause respiratory failure.
MERS, similarly, passed from bats to dromedary camels in the Middle East. That coronavirus circulated in the camel population undetected for decades before jumping to humans in 2012. So far, 858 people have died in 28 countries from the illness, which comes with fever, cough, and shortness of breath.
In Southeast Asia, fruit bats were the original hosts of the deadly Nipah virus, which emerged in Malaysia in 1998 and then again in India in 2001. The bats passed it to farmed pigs, which gave it to people. Patients experienced headaches and vomiting; many slipped into a coma and died.
Fruit bats in Africa have played a major role in Ebola outbreaks since 1976. The worst Ebola outbreak in history, however, came from a population of long-fingered bats. More than 11,000 people were killed from 2013 to 2016.
How to prevent zoonotic diseases from spilling over into people
At markets, the close proximity of shoppers and vendors to live and dead animals creates a prime breeding ground for zoonotic diseases.
"For cultural reasons in the region, people want to see the specific animals they're buying be slaughtered in front of them, so they know they're receiving the products they paid for," Emily Langdon, an infectious-disease specialist at the University of Chicago, wrote in an article. "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."
On January 22, authorities in Wuhan banned the trade of live animals at these markets. Officials also closed the seafood market where the coronavirus outbreak might have started. On February 3, the Chinese Communist Party announced a crackdown on illegal wildlife markets and trade across the country.
Many experts support this type of intervention to help prevent the spread of viruses.
"Governments must recognize the global public-health threats of zoonotic diseases," Christian Walzer, the executive director of the Wildlife Conservation Society's health program, said in a statement. "It is time to close live-animal markets that trade in wildlife, strengthen efforts to combat trafficking of wild animals, and work to change dangerous wildlife-consumption behaviors, especially in cities."
But according to Eric Toner, a senior scientist at Johns Hopkins University, more animal-to-human disease outbreaks are likely to arise, even without wet markets.
"I thought for a long time that the most likely virus that might cause a new pandemic would be a coronavirus," Toner told Business Insider. "We're in an age of epidemics because of globalization because of encroachment on wild environments."
Aria Bendix contributed reporting to this story.
- Read more about the Wuhan virus:
- Everything we know about the Wuhan virus sweeping across China
- Health experts issued an ominous warning about a coronavirus pandemic 3 months ago. The virus in their simulation could kill 65 million people.
- Wuhan, China, and at least 15 other cities have been quarantined as China attempts to halt the spread of the coronavirus.
- The Wuhan coronavirus has spread to at least 26 countries. Here's how to protect yourself while traveling.
