aSegalab S.A., Rua de Recarei, Leça do Balio, 44566-734 Leça do Balio, Portugal bInstituto de Ciências Biomédicas Abel Salazar, Universidade do Porto. Porto
A study to evaluate BVDV-prevalence, recent -contact and -vaccine use in dairy herds in the “Entre Douro e Minho” (EDM) region in North Portugal was carried out in 124 dairy herds in 2003. Herds were visited to ascertain BVDV-vaccine use and to collect a bulk tank milk (BTM) sample and serum from 1268 cattle to analyse BVDV-antibodies using an NS2-3 ELISA. Fifty-three percent of farmers used inactivated BVDV-vaccines whilst the remaining farmers were not presently using BVDV-vaccines. BMT-antibody results included 35% positives, 25% negative and 39% inconclusive, and were similar in vaccinated and non-vaccinated herds (p > 0.05) and allowed estimating a 10% BVDV herd-prevalence from prior knowledge of the relationship between BMT-antibody results and probability of PI cattle in the herd. Overall individual seroprevalence was 27% and was 23% in non-vaccinated and 36% in vaccinated cattle (p < 0.05). Contact of the herd with BVDV was assessed according to seroprevalence in young and adult cattle in the herd and it was estimated that 35% of herds were infected or had recent contact with BVDV, 40% were not infected and did not have recent contact with BVDV and the BVDV-infection and -contact status of remaining herds was undetermined. The results from this study indicate BVDV is endemic and BVDV-vaccines are widespread in the dairy-cattle population in EDM region in Portugal.
This article was published in Preventive Veterinary Medicine, 72, J. Niza-Ribeiroa,b, Adelaide Pereiraa, João Souzaa, Helena Madeiraa, Abigaíl Barbosaa and Carla Afonsoa, Estimated BVDV-prevalence, -contact and -vaccine use in dairy herds in Northern Portugal, 81-85, Copyright Elsevier 2005.