Looking for low doses of PRRS is critical for correctly identifying the source of infection in young pigs who were recently weaned. An outbreak of PRRS can have economic losses in finishing pigs. If any pigs are infected with PRRSv the group that the pig is with will likely suffer from the virus as well and put other herds of pigs at risk if they are all kept in a dense area. A way to detect low rats of PRRSv is needed to help producers handle their PRRS management, protect their bio-security investments, detect early any new PRRSv infections of their sow herd, monitor uninfected replacement gilts in isolation, and to optimize production planning. Low rates of PRRS in nursery pigs are possible because some gilts can carry the disease in utero and infect a small amount 0f litters in the herd. To detect low rates of infection in herds, large numbers of animals must be tested to detect at least one infected pig, 374 pigs would have to be tested to have 95% confidence. This study used a chew-rope which was hung in each pen of a PRRS infected nursery. It was hypothesized that sensitivity of detection could be increased with less labour cost. The rope chewing behavior provided valuable insight and data about PRRS infections of nursery-aged pigs. A least cost method for hanging rope has also been developed. This information is to be presented through various mediums in the future.