Piglets_Reuters

A swine virus deadly to young pigs, one never before seen in North America, is spreading rapidly across the United States and proving harder to control than previously believed.

The virus now has spread to 13 states – with more than 100 positive cases to date – since it was first diagnosed in the United States last month, said Montserrat Torremorell, the Allen D. Leman Chair in Swine Health and Productivity at the University of Minnesota’s College of Veterinary Medicine.

While the virus has not tended to kill older pigs, mortality among very young pigs infected in U.S. farms is commonly 50 percent, and can be as high at 100 percent, say veterinarians and scientists who are studying the outbreak.