Publish Date: April 29, 2022
Clinical outbreaks characterized by severe reproductive losses, respiratory disease, reduced growth, and increased mortality appeared in the United States in 1987 and then Europe in 1990. In 1991, researchers in the Netherlands determined the cause to be a previously unrecognized virus which they named "porcine reproductive and respiratory syndrome virus" (PRRSV) (Terpstra et al., 1991; Wensvoort et al., 1991). Today, PRRSV is present in most swine-producing regions of the world. PRRSV typically enters herds by the introduction of infected animals, virus-contaminated semen, aerosol spread, or breaks in biosecurity. Once infected, PRRSV tends to circulate in the herd indefinitely. This process is driven by persistent PRRSV infections (carrier animals) and the availability of susceptible animals introduced into the population through birth or purchase. In Europe and North America, the cost of PRRSV was estimated at $6.25 to $15.25 USD per pig marketed (Holtkamp et al. 2013; Nathues et al. 2017). Thus, PRRSV has a major impact on swine health and productivity, but consistent control in the field is difficult.