The goal of this project was to understand the impact of PRRS infected pigs on neighboring herds that are negative. In the original design, we proposed to collaborate with regional PRRS control projects and use data being collected to address the objective. After starting the project, we realized that not enough data was available to address the objective. In 2011, we requested and received approval for a change in protocol. In this new protocol, we proposed a prospective study assigning growing pig sites to vaccinated / not vaccinated. We proposed to collect data on virus dissemination and determine whether vaccination might influence this dissemination. We have aggressively sought out sites to participate.

Unfortunately, there seems to be sufficient sentiment that negative pigs at high risk of becoming infected should be PRRS vaccinated and therefore, we were unable to find enough owners willing to leave pigs unvaccinated. Consequently, in 2012 we proposed a different approach to address this same objective. The proposal built on work recently reported by Dee (2012) where he reported detecting PRRS virus in up to 75% of air samples in the month of March outside selected sow barns. Unfortunately, this request was declined and we were asked to terminate the study. BobM@UMN.Edu