A deadly pig virus has been discovered in Nebraska, making it the 20th state to be hit by Porcine Epidemic Diarrhea.

The disease had not been seen in North America until May when it was first discovered in the U.S. The disease has a high mortality rate among young piglets, with a 50 percent death rate on a farm infected with the virus common. However, USDA officials said in some cases the virus killed all the piglets on a farm.

Older pigs can be impacted by the disease but have a much lower mortality rate.

The National Pork Board has issued biosecurity guidelines to pork producers in an attempt to stop the epidemic. The spread of the virus is believed to be connected in some way with the trucking industry as most pigs are transferred via truck.

The deaths of piglets is leading market experts to see a steep decline in hog supplies through summer 2014.