Porcine reproductive and respiratory syndrome control in Saxony and Thuringia - Results of 2 voluntary regional programmes in the years 2011-2018

Abstract

The present study is intended to show the progress of voluntary porcine reproductive and respiratory syndrome (PRRS) control programmes in Thuringia and Saxony as well as to emphasize the importance of confirmation testing in the case of positive findings in unsuspicious herds. In order to present the progress of porcine reproductive and respiratory syndrome virus (PRRSV) elimination, the findings for the years 2011-2018 as well as data on the elimination programme, type and size of the farms, and use of PRRS vaccination were compiled. Each herd was assigned an antibody and PCR status for each year in order to analyze the relationship between status and year. Furthermore, the association between status and herd size as well as the use of PRRS vaccination were investigated. The relevance of confirmation testing is shown by the findings of the herds in the years following PRRSV elimination. In the majority of affected farms in Saxony, depopulation/repopulation was performed in order to eliminate PRRSV. In Thuringia, PRRSV elimination was frequently accomplished during ongoing production. A significant reduction of positive antibody and PCR findings was observed in both federal states during the investigation period. Higher antibody and PCR levels were evident in farms using PRRS vaccination. In the years following PRRSV elimination, positive PRRSV antibody findings occurred in individual PRRSV-unsuspicious farms. These were shown to be false-positive by use of confirmation tests. The proportion of PRRSV-positive herds in a region with low pig density can be reduced by voluntary control programmes with the eradication method playing a subordinate role. The use of vaccination against PRRSV or alternative control measures is to be considered carefully. In the case of positive findings in unsuspicious farms, confirmation testing is warranted in order to rule out any ongoing PRRS outbreak as well as to clarify the farm's status. Voluntary PRRS elimination and maintenance of the status of "PRRSV unsuspicious" is possible even when individual herds in the region do not participate in the control programme.