Virginia pork producers are closely watching their herds for signs of a deadly virus after the illness cropped up on farms in North Carolina.

Experts say there is no risk to humans who consume pork, even if the animal was infected with Porcine Epidemic Diarrhea Virus. About 430 farms in the United States — mostly in the Midwest — are affected, and measures have been instituted to help prevent the further spread of illness, officials say.

As its name suggests, the disease causes acute diarrhea in pigs and kills a majority of piglets. Adult pigs are better able to handle the effects of the disease.

The disease was first recognized in 1971 in Great Britain and since has spread throughout Europe and Asia, according to Mark Estienne, the swine extension specialist at Virginia Tech’s Tidewater Agricultural Research and Extension Center on Holland Road. However, the first known case of it in the United States was in May of this year.

Most recently, some farms in North Carolina owned by Smithfield Foods supplier Murphy-Brown have been infected, Murphy-Brown spokesman Don Butler said on Wednesday.

“We have had a very small number of farms affected by it and have implemented a lot of security,” Butler said. “We have a robust biosecurity program already, but in a situation like this we redouble our efforts.”

The company is restricting visits to farms from anyone other than necessary personnel, he said.

“We’ve put in a lot of additional measures to sanitize vehicles that deliver animals and feed,” he added.

The virus is spread via fecal-to-oral transmission, so any route by which even a small amount of fecal matter from an infected farm could make its way to an unaffected facility would spread the disease.

“It behaves similar to other diseases we’re aware of, and those diseases tend to die out in hot weather,” Butler said. “We’re hopeful the onset of warmer weather will help us stamp out this disease.”

Estienne reiterated that the disease is not a concern for human health or food safety.

“It’s a production concern,” he said. “The best way to deal with it is to keep it out of the farm. You don’t want visitors that have just come from another hog farm.”

Estienne said the pigs at the Holland Road research station have not shown any signs of the disease, nor has it been found anywhere else in Virginia.

Elaine Lidholm, director of communications for the Virginia Department of Agriculture and Consumer Services, is thankful for that.

“There were a couple or three cases in North Carolina,” she said. “They seem to have kept it confined to those three farms, so it may be that enhanced biosecurity is keeping it from spreading any more.”

Those three farms do not have any known connections to any in Virginia, such as common owners, so Lidholm said producers remain hopeful pigs in the commonwealth will not be affected.

“Most people have a high level of biosecurity anyway, but it certainly can’t hurt to take a look at it,” she said, recommending cleaning truck tires and dipping boots in antiseptic baths as good ways to avoid spreading the virus.