date:Apr 28, 2014
od safety issue, the USDA says.
ORIGIN MYSTERY
Months of forensic research so far have turned up no clear evidence of how the disease entered the United States.
The virus is nearly identical to one that infected pigs in China's Anhui province, according to a report published in the American Society of Microbiology journal mBio. Researchers also are exploring whether the widespread use of pig-blood byproducts in hog feed might have introduced the disease.
There have been outbreaks in recent y