Prevalence of bovine herpesvirus-1 in the Belgian cattle population

The national bovine herpesvirus 1 (BHV-1) seroprevalence (apparent prevalen ce) in the Belgian cattle population was determined by a serological survey that was conducted from December 1997 to March 1998. In a random sample of herds (N=556), all cattle (N=28 478) were tested for the presence of antib odies to glycoprotein B of BHV-1. No differentiation could be made between vaccinated and infected animals, because the exclusive use of marl;er vacci nes was imposed by law only in 1997 by the Belgian Veterinary Authorities. Twenty-one percent of the farmers vaccinated continuously against BHV-1. In the unvaccinated group, the overall herd, individual-animal and median w ithin-herd seroprevalences were estimated to be 67% (95% confidence interva l (CI)=62-72), 35.9% (95% CI=35.0-36.8) and 33% (quartiles=14-62), respecti vely. Assuming a test sensitivity and specificity of 99 and 99.7%, respectively, the true herd, individual-animal and median within-herd prevalence for the unvaccinated group of herds were estimated to be 65, 36 and 34%, respective ly. The true herd prevalence for dairy, mixed and beef herds were respectiv ely, 84, 89 and 53%; the true individual-animal prevalence for those types of herds were, respectively, 35, 43 and 31%; whereas, the true median withi n-herd prevalences were 36, 29 and 38%. (C) 2000 Elsevier Science B.V. All rights reserved.