Herd closure as a strategy to eradicate PRRSV not always a success in large sow herds

Understanding the dynamics of PRRSv persistence is essential for the development of successful PRRS control and eradication programs1. Among these, “Herd Closure” – a months long closure of the sow herd – is considered to be one of the most successful. It relies on consistent natural exposure that should provide a “sterilizing immunity” to all breeding stock on the farm leading to the natural disappearance of the virus by replacement of positive animals over