SARS from horseshoe bats: history repeating itself?
As the story about the new coronavirus was coming out, many were struck by a sense of déjà vu. Because this has happened before, in 2002, with an epidemic caused by another coronavirus: the one that caused the original SARS, or “severe acute respiratory syndrome”. Disease ecologist Peter Daszak worked to try and curb the spread of these two viruses that came two decades apart. The new coronavirus is genetically quite similar to SARS, and there’s a lot we can learn from exploring the past here, because as he told Phil Sansom, that is far from the only similarity…
Peter - The original SARS outbreak began in south China, Guangdong province, where there are some really large cities, like the city of Guangzhou with very big wildlife markets. People in South China have a tradition of eating wildlife. It's very strong and still continues. And they have really large markets that bring incredible diversity of animals together. And these animals can be in the wildlife trade for weeks; so they're swapping viruses around between each other, they're picking up new viruses; and then when they get to the market, there are thousands of people that go in and out of these markets. And SARS, the original SARS outbreak, began in a wildlife market. It was very clear. The first cases were related. And we started working there at the end of the outbreak to say, well, if the market is where it began, which animal did it come from, and where in China was that animal first caught, because the virus could still be out there.
Phil - What did you find?
Peter - At the time, people were saying that civets, these small ferret- or badger-like animals, were the source of the virus; and what we found was that's not really the case, that bats are the real reservoirs, they're the animals that carry these viruses, and have done probably for millions of years in the wild. And then the virus got into other species of animals in the markets, in the wildlife trade, and then got into people. So we traced the virus back to rural China. And we ended up in Yunnan province, which is a really beautiful part of southwest China which has a lot of wildlife diversity, a lot of intact countryside. And it looks like they were picked up by people hunting bats and bringing them into markets, and the virus spread then through the trade.
Phil - That certainly sounds a lot like SARS-CoV-2, because we really think that came originally from bats, don't we?
Peter - Yeah, without a doubt, it's pretty clear that bats are the origin. Every relative of the whole SARS group of viruses is found in bats, and the closest known relatives to SARS-CoV-2 are from bats as well.