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Thirty years into Porcine Respiratory and Reproductive Syndrome (PRRS) in North America, the industry is confident it can get PRRSv out of herds predictably, but the challenge continues to be reinfection of the breeding herd, said Dr. Roger Main, director of the Veterinary Diagnostic Laboratory at Iowa State University.

Dr. Rodger Main, director of the Veterinary Diagnostic Laboratory at Iowa State University, speaks to ThePigSite's Sarah Mikesell at the North American PRRS Conference in Chicago. 

Looking at a PRRSv timeline:

• About 20 years ago the first modified live vaccine that was developed and introduced and is still in use today.
• About 15 years ago, PIC helped the industry understood how to eliminate PRRS from breeding herds cost effectively without depopulation, using a tool or management practice called herd closure.
• Over the last 10 years, research has focused on PRRSv routes of transmission. 

"The primary hurdle that we're still trying to get over is controlling reinfection back into breeding herds," Dr. Main said. "There are some things we should be thinking differently about or more aggressively regarding how we're managing PRRS virus in growing pigs."

Growing pigs represent about 90 per cent of pigs that are controlling the shed and spread of the virus, making then a reservoir for subsequent breeding herd infection. Unfortunately, there's no silver bullet solution. 

"I think it's a combination of biosecurity and immunity," said Dr. Main. "How do we look at that reservoir and say 'how can we better manage PRRS in this growing pig population', not only to control the disease in growing pigs but more over to reduce the risk of PRRS virus getting back into these breeding herds."

Dr. Main was a presenter at the North American PRRS Sysmposium, sponsored by Boehringer Ingelheim.