A study shows bats are responsible for killing 25,000 pigs in China. Based on genetic analysis, Chinese researchers determine horseshoe bat were responsible for spreading a new coronavirus.
Piglets mysteriously started having intense diarrhea, vomiting and death on farms in China’s southeastern Guangdong province in 2016. By May 2017, the disease had killed 24,693 piglets.
Until now, tests failed to pin the outbreak. Utilizing DNA from sick pigs, the researchers identify the new coronavirus- Swine Acute Diarrhea Syndrome (SADS-CoV) and the cause of the puzzling disease.
SADS-CoV began killing piglets on a farm near Foshan in Guangdong Province in late October 2016. Initially, it was suspected porcine epidemic diarrhea virus as the cause. Detection of PEDV ceased by mid-January 2017, yet piglets continued to die, suggesting a different cause.
Scientists confirmed the connection of SADS-CoV to bats by identifying the new virus in the small intestine of piglets from the outbreak. They determined the genetic sequence of SADS-CoV is like that of a bat coronavirus discovered in 2007 and looked for evidence of SADS-CoV in bat specimens collected from 2013 to 2016 in Guangdong Province. It shares 95% of its genetic code with another coronavirus, HKU2, detected in cave-dwelling horseshoe bats.
Interestingly, the research team found striking similarities between SADS-CoV and Severe Acute Respiratory Syndrome (SARS)– a highly infectious virus that killed humans in China in 2002 and 2003- in geographical, temporal, ecological and etiological settings. SADS-CoV came from horseshoe bats in a region near the origin of SARS.
Figure 1: Map of outbreak locations and sampling sites in Guangdong province, China and the co-circulation of PEDV and SADS-CoV during the initial outbreak on farm A. SADS-affected farms are labeled (farms A–D) with blue swine silhouettes following the temporal sequence of the outbreaks. Bat sampling sites are indicated with black bat silhouettes. The bat SADSr-CoV that is most closely related to SADS-CoV (sample 162140) originated in Conghua. The red flag marks Foshan city, the site of the SARS index case.
Evidence suggests these two coronaviruses share a common ancestor and that SADS-CoV jumped from bats to pigs, researchers report April 4 in Nature. While the first documented human cases of SARS emerged 60 miles from pig farms hit by SADS-CoV, the disease doesn’t appear to infect humans as indicated by no positive test for SADS-CoV found in farm workers.
This study highlights the importance of identifying coronavirus diversity and distribution in bats to mitigate future outbreaks that could threaten livestock, public health and economic growth. The researchers say the finding is an important reminder that identifying new viruses in animals and quickly determining their potential to infect people is a key way to reduce global health threats.
The research was a collaboration among scientists from EcoHealth Alliance, Duke-NUS Medical School, Wuhan Institute of Virology and other organizations, and was funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health. The research is published in the journal Nature.