A new strain of the Porcine Reproductive and Respiratory Syn­­drome (PRRS) virus is hitting farms in Iowa and Minnesota with unusually high piglet mortality and abortion in sows.

“Producers for years have developed strategies to deal with PRRS and PRRS outbreaks,” said Iowa’s State Veterinarian Jeff Kaisand. “But somehow the change in the virus this time … it’s causing severe clinical signs and high mortality.”

Named 1-4-4 L1C, the new variant was first identified last year in Minnesota. Since then, outbreaks have occurred in as many as 20% of the breeding herds in Minnesota and about 4% ...