(Reuters) - Confirmed cases of Porcine Epidemic Diarrhea Virus increased by 296 in the week ended March 15, bringing the total number to 4,757, according to data released on Thursday by the U.S. Department of Agriculture's National Animal Health Laboratory Network (NAHLN).
The U.S. and Canadian hog industries have recently developed partnerships to research what role, if any, feed or feed ingredients have had in the transmission of PEDv, the National Pork Board said earlier this week. The report from USDA's NAHLN does not include test results from feed samples.
No new states reported cases leaving the affected states at 27, the group of animal researchers said.
While one case can represent an individual animal or an entire herd at a single site, hog industry analysts estimate PEDv has killed an estimated 5 million U.S. hogs since it was discovered in May 2013.
"Unfortunately it has spread rapidly this winter, especially here in Ohio," said Duane Stateler, Ohio Pork Council president and hog producer with a 7,200 head operation.
PEDv, which does not affect humans and is not a food safety risk, causes diarrhea, vomiting and severe dehydration in pigs. While older pigs have a chance of survival, 80 to 100 percent of piglets that contract it die.
"The smaller the pig the harder it is for them to recover and come back," Stateler said.
The U.S. hog industry has grappled with tactics to contain the spread of the highly contagious pig virus using strict biosecurity measures as its main line of defense.
The spread of the virus has already crimped market ready hog supply not only in the U.S. Midwest but also along the East Coast, forcing some pork packing plants to reduce slaughter operations.
There is talk in the hog industry of some Midwest pork packing facilities considering several operations of either cutting one day a week, trimming daily operating hours, or eliminating Saturdays and overtime in order to reduce total operating hours, hog dealers have said.
Last week, Smithfield Foods Inc. suspended hog slaughter on Friday at its Tar Heel, North Carolina, plant which has a slaughter capacity of 30,000 to 34,000 head as PEDv has tightened hog supplies, industry sources said.