MARKED REDUCTION OF THE PREVALENCE OF PSEUDORABIES VIRUS-INFECTED PIGS IN PIG DENSE REGIONS OF THE NETHERLANDS DURING THE FIRST YEAR OF A NATIONWIDE VACCINATION CAMPAIGN

The breeding and finishing pig populations in four Animal Health Servi ce regions in the Netherlands were monitored with respect to pseudorab ies virus (PRV) seroprevalence. Analysis of data of the seroprevalence survey of 1994 indicated that two samples per herd was sufficient to estimate the seroprevalence in both the sow and finishing pig populati ons. In the northern, eastern, southern, and western regions, 115, 645 , 940, and 218 sow herds and 114, 1036, 954, and 323 pig finishing her ds were sampled, respectively. In the breeding pig population, the PRV -seroprevalence decreased from 27% to 17% in the eastern region, from 32% to 17% in the southern region, from 18% to 12% in the western regi on, and from 10% to 6% in the northern region. In the finishing pig po pulation, the PRV-seroprevalence decreased from 15% to 6% in the easte rn region, from 19% to 6% in the southern region, and from 12% to 5% i n the western region. There was no significant difference in PRV serop revalence in finishing pigs in the northern region between the survey of 1994 and 1995.