Eradication of PRRS is possible on an individual farm basis, however; re-infection via local spread of the virus is a frequent event. Proof of knowledge on the routes of PRRSV transmission and biosecurity is necessary before large-scale eradication efforts can begin. The specific aims of this study are to assess the efficacy of three levels of biosecurity on reducing the risk of PRRSV transmission to naïve pig populations; to evaluate the role of season on PRRSV area spread; to estimate the frequency and significance of observed routes of PRRSV transmission and to compile a bilingual PRRSV-biosecurity manual summarizing routes, intervention and monitoring protocols for use on commercial farms. After five replicates the preliminary results for the high level facility is that all samples collected remained negative. The results from the medium level facility confirmed evidence of RNA in aerosols with subsequent infection of pigs. In the low level facility evidence was confirmed of RNA in marked flies with subsequent infection in pigs and there was no evidence of RNA in externally collected samples and no infection of pigs. Other preliminary results conclude that during the cool weather in June there was an outbreak of the PRRS virus; however, there was minimal spread during the hot weather in July. The next studies to be conducted will be large-scale, long-term demonstration projects under controlled field conditions.