Prioritization of pig farm biosecurity for control of Salmonella and hepatitis E virus infections; results of a European Expert Opinion Elicitation

AbstractBackground: In the literature, there is absent or weak evidence on the effectiveness of biosecurity measures to the control ofSalmonellaspp. and hepatitis E virus (HEV) on pig farms. Therefore, the present study aimed to collect, weigh, and compare opinions from experts on the relevance of several biosecurity measures. An online questionnaire was submitted to selected experts, from multiple European countries, knowledgeable on either HEV orSalmonella, in either indoor or outdoor pig farming systems (settings). The experts ranked the relevance of eight biosecurity categories with regards to effectiveness in reducing the two pathogens separately, by assigning a score from a total of 80, and within each biosecurity category they scored the relevance of specific biosecurity measures (scale 1–5). Agreement among experts was analysed across pathogens and acrosssettings. Results: After filtering for completeness and expertise, 46 responses were analysed, with 52% of the experts identified as researchers/scientists, whereas the remaining 48% consisted of non-researchers, veterinary practitioners and advisors, governmental staff, and consultant/industrial experts. The experts self-declared their level of knowledge but neither Multidimensional Scaling nor k-means cluster analyses produced evidence of an association between expertise and the biosecurity answers, and so all experts’ responses were analysed together without weighting or adaptation. Overall, the top-ranked biosecurity categories werepig mixing;cleaning and disinfection;feed, water and bedding; andpurchase of pigs or semen, while the lowest ranked categories weretransport,equipment,animalsandhumans.Cleaning and disinfectionwas ranked highest for both pathogens in the indoor setting, whereaspig mixingwas highest for outdoorsettings. Several (94/222, 42.3%) measures across all foursettingswere considered highly relevant. Measures with high disagreement between the respondents were uncommon (21/222, 9.6%), but more frequent for HEV compared toSalmonella. Conclusions: The implementation of measures from multiple biosecurity categories was considered important to controlSalmonellaand HEV on farms, and pig mixing activities, as well as cleaning and disinfection practices, were perceived as consistently more important than others. Similarities and differences in the prioritised biosecurity measures were identified between indoor and outdoor systems and pathogens. The study identified the need for further research especially for control of HEV and for biosecurity in outdoor farming.