A lawsuit filed by an Indiana pork producer potentially threatens the progress of the porcine reproductive and respiratory syndrome (PRRS) regional control projects.

The lawsuit alleges that employees at one farm intentionally infected pigs with the PRRS virus and that infection accidentally infected a neighbor’s swine.

The farm owner denies the procedure was connected with the neighbor’s outbreak and has sought dismissal of the suit.

Wilhoite Family Farms, which operates farms in Boone and Tippecanoe counties in west central Indiana, is suing Dale Johnson, who operates a farm near Wilhoite’s Tippecanoe County operation, and TDM Farms, which owns pigs at Johnson’s farm. Whilhoite alleges his pigs became infected with the PRRS virus through airborne transmission or other means following infection of TDM pigs. TDM and Johnson have denied the pigs were the source of the strain that infected the Wilhoite pigs.

Intentional infection is a widespread practice, and if the lawsuit is successful, it could affect regional PRRS virus elimination projects being developed nationwide, says Derald Holtkamp, DVM, a professor at Iowa State University. He is also director of the American Association of Swine Veterinarians Production Animal Disease Risk Assessment Program.

The regional projects vary from a single county to multiple counties and rely on sharing information and working collaboratively, he says.

“All of those rely on trust, working together and sharing information that could potentially be used against them in a case like this,” Holtkamp explains.

He adds that figures from a pending study clearly show that PRRS is causing more economic harm to pork producers than the $560 million annually estimated in a previous study.

Increased prevalence of the disease and increased pathogenicity of some of the current strains add to economic costs, despite improved ability to manage outbreaks, Holtkamp says. The PRRS virus is widespread, easily transmitted over long distances and able rapidly develop new strains in the absence of widely effective control strategies that have hurt eradication efforts.

This report will appear in the May 1, 2011 issue of the Journal of the American Veterinary Medical Association.