A mysterious outbreak in China that killed nearly 25,000 pigs has been traced to bats—an important reminder, researchers say, that identifying new animal viruses quickly and understanding the potential threat to humans are vital to thwarting global disease.
In late October 2016, pigs on farms in China’s Guangdong Province mysteriously started presenting with extreme diarrhea and vomiting. By May of the following year, the unidentified disease had killed nearly 25,000 piglets across 4 farms. The outbreak ceased, but initial tests failed to positively identify a common pig virus as the cause of the epidemic.
Now, that unknown killer has been identified as a new kind of coronavirus, swine acute diarrhea syndrome coronavirus (SADS-CoV). Research and evidence published in the April 4 issue of Nature indicate that the virus originated in bats, which have long been recognized as one of the most important hosts for emerging zoonotic viruses.
The authors of this study also note that the outbreak began in the same vicinity as the origin of the 2002 SARS pandemic that killed more than 750 people worldwide. “There were striking similarities between the SADS and SARS outbreaks in geographical, temporal, ecological and aetiological settings,” they wrote.
The researchers were able to pinpoint SADS-CoV and its origin by analyzing samples from sick piglets and piecing together a genetic blueprint of the virus. Through analysis, they discovered that the viral outbreak in the piglets shared large portions of its genetic code with the coronavirus HKU2, which was detected in cave-dwelling horseshoe bats. The evidence suggests these 2 coronaviruses share a common ancestor and that SADS jumped from bats to pigs.
The work was a collaboration among scientists from various organizations, including the New York—based EcoHealth Alliance, Duke-National University of Singapore Medical School, and Wuhan Institute of Virology in Wuhan, China. It was funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.
To date, no farm workers who had close contact with the infected pigs have tested positive for SADS-CoV, and the disease is not believed to infect humans.