Or something like that. Scientific American looks at how Shi Zhengli’s kind of obscure area zoological research – looking at how bats contract viral diseases – suddenly became super important – for this pandemic, and possibly the next dozen… or 5,000:
“It’s incredibly important to pinpoint the source of infection and the chain of cross-species transmission,” says disease ecologist Peter Daszak, president of EcoHealth Alliance, a New York City–based nonprofit research organization that collaborates with scientists, such as Shi, around the world to discover new viruses in wildlife. An equally important task, he adds, is hunting down other related pathogens—the “known unknowns”—in order to “prevent similar incidents from happening again.”
Before SARS, the world had little inkling of coronaviruses—named because, seen under a microscope, their spiky surface resembles a crown—says Linfa Wang, who directs the emerging infectious diseases program at Singapore’s Duke-NUS Medical School. Coronavirues were mostly known for causing common colds. “The SARS outbreak was a game changer,” says Wang, whose work on bat-borne coronaviruses got a swift mention in the 2011 Hollywood blockbuster Contagion. It was the first time a deadly coronavirus with pandemic potential emerged. This discovery helped to jump-start a global search for animal viruses that could find their way into humans.
Shi was an early recruit of that worldwide effort, and both Daszak and Wang have since been her long-term collaborators. But how the civets got the virus remained a mystery. Two previous incidents were telling: Australia’s 1994 Hendra virus infections, in which the contagion jumped from horses to humans, and Malaysia’s 1998 Nipah virus outbreak, in which it moved from pigs to people. Both diseases were found to be caused by pathogens that originated in fruit-eating bats. Horses and pigs were merely the intermediate hosts.
In those first virus-hunting months in 2004, whenever Shi’s team located a bat cave, it would put a net at the opening before dusk—and then wait for the nocturnal creatures to venture out to feed for the night. Once the bats were trapped, the researchers took blood and saliva samples, as well as fecal swabs, often working into the small hours. After catching up on some sleep, they would return to the cave in the morning to collect urine and fecal pellets.
But sample after sample turned up no trace of genetic material from coronaviruses. It was a heavy blow. “Eight months of hard work seemed to have gone down the drain,” Shi says. “We thought coronaviruses probably did not like Chinese bats.” The team was about to give up when a research group in a neighboring lab handed it a diagnostic kit for testing antibodies produced by people with SARS.
There was no guarantee the test would work for bat antibodies, but Shi gave it a go anyway. “What did we have to lose?” she says. The results exceeded her expectations.
Three years earlier, Shi’s team had been called in to investigate the virus profile of a mineshaft in Yunnan’s mountainous Mojiang County—famous for its fermented Pu’er tea—where six miners suffered from pneumonialike diseases (two of them died). After sampling the cave for a year the researchers discovered a diverse group of coronaviruses in six bat species. In many cases, multiple viral strains had infected a single animal, turning it into a flying factory of new viruses.
“The mineshaft stunk like hell,” says Shi, who went in with her colleagues wearing a protective mask and clothing. “Bat guano, covered in fungus, littered the cave.” Although the fungus turned out to be the pathogen that had sickened the miners, she says it would only have been a matter of time before they caught the coronaviruses if the mine had not been promptly shut.
With growing human populations increasingly encroaching on wildlife habitats, with unprecedented changes in land use, with wildlife and livestock transported across countries, with their products transported around the world, and with a sharp increase in both domestic and international travel, new disease outbreaks of pandemic scale are a near mathematical certainty. This had been keeping Shi and many other researchers awake at night—long before the mysterious samples landed at the Wuhan Institute of Virology on that ominous evening last December.
About a year ago, Shi’s team published two comprehensive reviews about coronaviruses in Viruses and Nature Reviews Microbiology. Drawing evidence from her own studies—many of which were published in top academic journals—and from others, Shi and her co-authors warned of the risk of future outbreaks of bat-borne coronaviruses.
By January 7 the Wuhan team determined that the new virus had indeed caused the disease those patients suffered—a conclusion based on results from polymerase chain reaction analysis, full genome sequencing, antibody tests of blood samples and the virus’s ability to infect human lung cells in a petri dish. The genomic sequence of the virus—now officially called SARS-CoV-2 because it is related to the SARS pathogen—was 96 percent identical to that of a coronavirus the researchers had identified in horseshoe bats in Yunnan, they reported in a paper published last month in Nature. “It’s crystal clear that bats, once again, are the natural reservoir,” says Daszak, who was not involved in the study.
On February 24 the nation announced a permanent ban on wildlife consumption and trade except for research or medicinal or display purposes—which will stamp out an industry worth $76 billion and put approximately 14 million people out of jobs, according to a 2017 report commissioned by the Chinese Academy of Engineering. Some welcome the initiative, whereas others, such as Daszak, worry that without efforts to change people’s traditional beliefs or provide alternative livelihoods, a blanket ban may push the business underground. This could make disease detection even more challenging. “Eating wildlife has been part of the cultural tradition in southern China” for thousands of years, Daszak says. “It won’t change overnight.”
In any case, Shi says, “wildlife trade and consumption are only part of problem.” In late 2016 pigs across four farms in Qingyuan county in Guangdong—60 miles from the site where the SARS outbreak originated—suffered from acute vomiting and diarrhea, and nearly 25,000 of the animals died. Local veterinarians could not detect any known pathogen and called Shi for help. The cause of the illness, called swine acute diarrhea syndrome (SADS), turned out to be a virus whose genomic sequence was 98 percent identical to a coronavirus found in horseshoe bats in a nearby cave.
[via Jane Qiu]