(Reuters) - North Dakota is the latest state to confirm a case of a deadly pig virus which has killed an estimated 4 million pigs in the United States since its discovery in the spring of 2013.
The first North Dakota case of Porcine Epidemic Diarrhea virus, or PEDv, was confirmed in the eastern part of the state this week, the North Dakota State University Extension Service said in a statement on Thursday.
Confirmed PEDv cases increased by 304 in the week of February 16 week bringing the total number of confirmed cases to 3,856 in 25 states, according to data released on Thursday from the USDA's National Animal Health Laboratory Network. The data did not include the North Dakota case.
The virus does not affect humans and is not a food safety risk.
Four Canadian provinces have also confirmed cases of the virus, which 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.
"Farms impacted by PEDv can see high mortality rates in piglets for three to five weeks, typically," said David Newman, swine specialist at North Dakota State University.
The U.S. hog industry expected to see tightening pig supplies in the spring and summer of 2014, but the virus has spread quickly, constricting the supply of slaughter-ready hogs and increasing costs of pork packers, Midwest hog dealers say.
Several U.S. states, including North Dakota, Washington and Oregon, now require imported pigs to have a certificate of health verified by a veterinarian that the animals do not have PEDv and have not been exposed to PEDv.(Reporting By Meredith Davis in Chicago; Editing by Grant McCool)