The comparison of existing and alternative surveillance strategies to prove freedom of BHV1 in dairy herds: A case study within the RISKSUR project

This study aimed at the application of the RISKSUR surveillance design framework to describe and redesign the surveillance program of bovine herpesvirus type 1 (BHV1) as laid down by EU-legislation. Scenario-tree analyses were carried out to determine surveillance system sensitivities (and components thereof) and the monthly herd-level confidence of freedom with two different surveillance designs. At a within-herd design prevalence of 10%, the conventional (EU) design led to a varying probability of freedom between 99.6-100% in an endemic situation, compared to a constant probability of freedom of >99.8% in the alternative design. In a disease-free situation, both designs performed equally well. The RISKSUR surveillance design framework provided easy-to-use guidance to describe and redesign the BHV1 surveillance program, potentially contributing to a standardisation of surveillance documentation. The assessment of various surveillance designs could be highly useful to support decision-making towards a more risk-based approach of animal health surveillance.