Descriptive analysis of national bovine viral diarrhoea test data in England.

Background: Bovine viral diarrhoea virus (BVDV) causes substantial economic losses to cattle herds; however, control and eradication can be achieved by identifying and removing persistently infected cattle. Each UK nation has separate control programmes. The English scheme, BVDFree, started in 2016 and is voluntary. Methods: We analysed the test results submitted to BVDFree from 5,847 herds from 2016 to 2020. Results: In 2020, 13.5% of beef breeder herds and 20.0% of dairy herds had at least one positive test result. Though lower than in previous years, there was no clear trend in the proportion of positive tests over time. In antigen testing herds, 1.5% of tests from antigen positive herds were positive, which was 0.4% of tests from all antigen testing herds. Dairy herds and larger herds were more likely to join BVDFree and dairy herds were also more likely to antigen test than beef breeder herds. Larger herds, herds that used individual antigen testing and herds that had BVD positive test results were more likely to continue submitting tests to BVDFree. Conclusions: The findings provide a benchmark for the status of BVD control in England; continued analysis of test results will be important to assess progress towards eradication.