Identification of pseudorabies virus-infected swine herds by evaluating the serostatus of boars or finishing pigs.

Data were collected from 39 Minnesota swine farms quarantined for pseudorabies virus (PRV) infection. Each herd was serologically evaluated for antibodies to PRV in the sows, boars, and finishing pigs. To identify PRV-seropositive swine herds, the Kappa statistic was used to estimate the effectiveness of evaluating the PRV serostatus of boars or of finishing pigs. Using the serostatus of all herd boars, the sensitivity (with 95% confidence interval) of identifying PRV-infected herds was 58 +/- 22%, and the specificity was 100 +/- 0%; Kappa statistic was 0.55. Using the serostatus of a representative sample of finishing pigs, the sensitivity of identifying PRV-infected herds (with 95% confidence interval) was 63 +/- 22%, and specificity was 87 +/- 23%; Kappa statistic was 0.40. The PRV serostatus of herd boars or of a representative sample of finishing pigs did not accurately reflect the PRV serostatus of the herd.