Prevalence of herds with young sows seropositive to pseudorabies (Aujeszky's disease) in northern Belgium

In Belgium, pseudorabies in swine has been the subject of a mandatory eradi cation programme since 1993, From December 1995 to February 1996, a survey was conducted in the five provinces of northern Belgium to estimate the pro vincial pseudorabies virus (PRV) herd seroprevalence. Seven hundred and twe nty randomly selected herds were included in this survey. To detect recentl y infected animals, only young sows were sampled. The results show that 44% of these herds had an important number of PRV-seropositive young sows. The highest herd seroprevalence was observed in West Flanders (68%), followed by Antwerp (60%), East Flanders (43%), Limburg (18%), and Flemish Brabant ( 8%), Assuming a diagnostic test sensitivity and specificity of 95% and 99%, respectively, and a true PRV within-herd prevalence of 43%, the overall tr ue PRV herd prevalence was estimated to be 35%. A logistic multiple-regress ion revealed that the presence of finishing pigs was associated with a two- fold increase in odds of a herd being seropositive (odds ratio (OR)=2.07, 9 5% confidence interval (CI)=1.31-3.26); a breeding herd size greater than o r equal to 70 sows was associated with a four-fold increase in odds of a he rd being seropositive (OR=4.09, 95% CI=2.18-7.67); a pig density in the mun icipality of greater than or equal to 455 pigs/km(2) was associated with a 10-fold increase in odds of a herd being seropositive (OR=9.68, 95% CI=5.17 -18.12). No association was detected between the PRV herd seroprevalence an d purchase policy of breeding pigs (purchased gilts , or use of homebred gi lts only). (C) 1999 Elsevier Science B.V. All rights reserved.