Campbell, EmmaMcConville, JamesClarke, JoeDonaghy, AoibheannMoyce, AsaByrne, Andrew W.Verner, SharonStrain, SamMcKeown, Ignatius M.Borne, PaulGuelbenzu-Gonzalo, Maria2021-02-032021-02-032021-01-12Campbell, E., McConville, J., Clarke, J., Donaghy, A., Moyce, A., Byrne, A. W., Verner, S., Strain, S., McKeown, I. M., Borne, P. and Guelbenzu‐Gonzalo, M. (2021) ‘Pestivirus apparent prevalence in sheep and goats in Northern Ireland: A serological survey’, Veterinary Record. Wiley, 188(1), pp. 42–48. doi: 10.1002/vetr.1.0042-4900https://doi.org/10.1002/vetr.1Publication history: Accepted - 30 October 2020; Published - 12 January 2021.Background: Bovine viral diarrhoea virus (BVDV) and border disease virus (BDV) can cause significant health problems in ruminants and economic impacts for farmers. The aim of this study was to evaluate pestivirus exposure in Northern Ireland sheep and goat flocks, and to compare findings with a previous study from the region. Methods: Up to 20 animals were sampled from 188 sheep and 9 goat flocks (n = 3,418 animals; 3,372 sheep and 46 goats) for pestivirus antibodies. Differentiation of the causative agent in positive samples was inferred using serum neutralisation. Abortion samples from 177 ovine cases were tested by BVDV reverse-transcription polymerase chain reaction and antigen ELISA. Results: Apparent animal and flock (one antibody positive animal within a flock) prevalence was 1.7% and 17.3%, respectively, a statistically significant drop in apparent prevalence since a survey in 1999. 52.6% of samples testing positive had higher antibody titres to BVDV than to BDV. Of the ovine abortion samples, only one positive foetal fluid sample was detected by ELISA. Conclusion: The present study found that, since 1999, there has been a decrease in apparent animal and flock prevalence of 3.7 and 12.8 percentage points respectively, suggesting pestivirus prevalence has decreased across Northern Ireland between 1999 and 2018.en© 2021 The Authors. Veterinary Record published by JohnWiley & Sons Ltd on behalf of British Veterinary Association. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.Bovine Viral DiarrhoeaBorder DiseasePestivirusNorthern IrelandEradicationArticle