A description and qualitative comparison of the elements of heterogeneous bovine viral diarrhea control programs that influence confidence of freedom

摘要

For endemic infections in cattle that are not regulatedat the European Union level, such as bovine viraldiarrhea virus (BVDV), European Member States haveimplemented control or eradication programs (CEP)tailored to their specific situations. Different methodsare used to assign infection-free status in CEP; therefore,the confidence of freedom associated with the“free” status generated by different CEP are difficult tocompare, creating problems for the safe trade of cattlebetween territories. Safe trade would be facilitated withan output-based framework that enables a transparentand standardized comparison of confidence of freedomfor CEP across herds, regions, or countries. The currentpaper represents the first step toward developmentof such a framework by seeking to describe and qualitativelycompare elements of CEP that contribute toconfidence of freedom. For this work, BVDV was usedas a case study. We qualitatively compared heterogeneousBVDV CEP in 6 European countries: Germany,France, Ireland, the Netherlands, Sweden, and Scotland.Information about BVDV CEP that were in placein 2017 and factors influencing the risk of introductionand transmission of BVDV (the context) were collectedusing an existing tool, with modifications to collectinformation about aspects of control and context. Forthe 6 participating countries, we ranked all individualelements of the CEP and their contexts that could influencethe probability that cattle from a herd categorizedas BVDV-free are truly free from infection. Manydifferences in the context and design of BVDV CEPwere found. As examples, CEP were either mandatoryor voluntary, resulting in variation in risks from neighboringherds, and risk factors such as cattle density andthe number of imported cattle varied greatly betweenterritories. Differences were also found in both testingprotocols and definitions of freedom from disease. Theobserved heterogeneity in both the context and CEPdesign will create difficulties when comparing differentCEP in terms of confidence of freedom from infection.These results highlight the need for a standardizedpractical methodology to objectively and quantitativelydetermine confidence of freedom resulting from differentCEP around the world.