Descriptive analysis of national bovine viral diarrhoea test data in England (2016-2020)

Abstract

Background: Bovine viral diarrhoea virus (BVDV) causes substantial economic losses to the cattle industry; however, control and eradication can be achieved by identifying and removing persistently infected cattle from the herd. 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 5847 herds between 2016 and 2020.

Results: In 2020, 13.5% of beef breeders and 20.0% of dairy herds that submitted tests had at least one positive (virus/antibody) test result. Although lower than in previous years, there was no clear trend in the proportion of positive tests over time. In virus testing herds, 0.4% of individual tests were positive in 2020, and 1.5% of individual tests were positive in BVDV-positive virus testing herds. Dairy herds and larger herds were more likely to join BVDFree, and dairy herds were also more likely to virus test than beef breeder herds. Larger herds, herds that used virus testing and herds that had BVDV-positive test results were more likely to continue submitting tests to BVDFree.

Conclusions: The findings provide a benchmark for the status of BVDV control in England; continued analysis of test results will be important to assess progress towards eradication.

Keywords: BVDFree England; antibody testing; bovine viral diarrhoea; disease eradication scheme; virus testing.

FIGURE 1

Number of holdings recruited to BVDFree for the first time (recruited) and total number of holdings submitting test results to BVDFree (tested) per calendar year. There are 5611 holdings in total

FIGURE 2

Locations of 5611 herds submitting tests to BVDFree each year for 2016–2020

FIGURE 3

Percentage of antibody or virus testing beef breeder herds (red circles) or dairy herds (blue triangles) positive for bovine viral diarrhoea antibody or virus with binomial 95% confidence interval error bars

FIGURE 4

Proportion of beef breeding and dairy herds in each region of England testing positive for bovine viral diarrhoea (BVD) virus or antibody in 2019 and 2020, with binomial 95% confidence intervals below. Darker red shading corresponds to a higher proportion of herds testing positive for BVD virus or antibody

FIGURE 5

Percentage of individual bovine viral diarrhoea virus tests returning a positive result for all virus testing herds (red triangles) and virus‐positive herds (blue circles) each calendar year. Error bars represent the binomial 95% confidence interval

FIGURE 6

Percentage of individual bovine viral diarrhoea antibody tests returning a positive result for all antibody testing herds (red triangles) and antibody‐positive herds (blue circles) each calendar year. Error bars represent the binomial 95% confidence interval