Elida M. Bautista, BS; Robert B. Morrison, DVM, PhD; Sagar M. Goyal, DVM, PhD;James E. Collins, DVM, PhD; and Joseph F. Annelli, DVM, MS
Outbreaks of porcine reproductive and respiratory syndrome (PRRS) in the United States were first reported in 1987, peaked in 1989-90, and stabilized in 1991-92. Recent data from many laboratories indicate that subclinical infections with PRRS virus may also be common. Limited serological studies have indicated that PRRS virus is widespread across the United States.
The objective of this study was to determine the seroprevalence of PRRS virus in swine herds in the United States. For this purpose, we used sera collected in 1990 as part of the National Animal Health Monitoring System (NAHMS) survey of 412 randomly selected swine herds in 17 states. Blood samples from up to 10 sows and/or gilts were collected from each herd.The sera were tested for PRRS virus (VR-2332 strain) antibodies by an indirect-fluorescent antibody (IFA) test.
Sera from 123 herds were also tested for antibodies to the Lelystad strain of PRRS virus. The prevalence of seropositive herds ranged from 0% in Oregon, Pennsylvania, and Tennessee to 82% in Michigan.
The mean and median seroprevalence of herds within states was 33% and 29%, respectively.These data indicate that at the time of this serologic survey, PRRS virus infection was common in the United States