[Association between management factors and herd status regarding Porcine Reproductive and Respiratory Syndrome virus infection - An analysis in the course of a voluntary PRRSV control program in Saxony and Thuringia]. / Beziehungen zwischen Managementfaktoren und Bestandsstatus bezüglich Infektion mit dem Virus des Porzinen Reproduktiven und Respiratorischen Syndroms.

OBJECTIVE: In Saxony and Thuringia, federal states of Germany with a low density of commercial pig farms, a voluntary program aims at controlling porcine reproductive and respiratory syndrome virus (PRRSV) infection. This targets the eradication of the infection on a herd level which has previously been achieved in a subset of herds. The presented study aimed at identifying management factors related with a positive or a negative PRRSV antibody (AB status) or PRRSV genome status (PCR status) on a herd level. MATERIAL AND METHODS: Data were collected in 82 farms in a region implementing a voluntary PRRSV control program. The test findings for the years 2011 to 2018 were compiled for each year and associated with the interrogated parameters. A generalized linear mixed model was used to identify factors associated with the AB and PCR status. RESULTS: The variables "separation of contaminated and non-contaminated areas on the loading ramp" (p = 0.012), "separation of gilts and sows" (p = 0.017) and "recording of visitors in a book" (p = 0.046) were negatively associated with the PCR status. In contrast, "separation of gilts and finishers" (p = 0.044) as well as the existence of "separated alleyways" (p = 0.042) were positively related to the PCR status. "Vaccination against PRRSV" was positively associated with the AB status and the PCR status (p = 0.005 and p = 0.001, respectively). In numerous variables, a low variability was observed. CONCLUSION: Certain biosecurity measures to control the movement of animals (separation of contaminated and not contaminated areas on the loading ramp) or people (recording of visitors) contribute to a successful reduction of PRRSV infections and a negative herd status. CLINICAL RELEVANCE: A combination of different measures may reduce PRRSV spread within pig herds. Breaking the infection cycle in gilts, either by separation of gilts from older sows or immunization, may be considered as a key aspect, presumably additionally supported by keeping gilts together with fattening pigs.

[Porcine reproductive and respiratory syndrome control in Saxony and Thuringia - Results of 2 voluntary regional programmes in the years 2011-2018]. / Bekämpfung des Porzinen Reproduktiven und Respiratorischen Syndroms in Sachsen und Thüringen.

OBJECTIVE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. CLINICAL RELEVANCE: 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.