In the United States, the clinical disease was first discovered and described in 1987–88 in North Carolina, Iowa and Minnesota. PRRS spread rapidly, both in Europe and North America. By the end of 1992, the disease was reported in Canada, Great Britain and several European countries.
The disease was first described as a syndrome and confused initially with several other diseases. It was referred to as swine mystery disease (SMD) or swine infertility and respiratory syndrome (SIRS), before porcine reproductive and respiratory syndrome (PRRS) became the generally agreed-upon name.
Since the PRRS virus is made up of RNA genetic material (instead of DNA), there is a lot of variation in the virus makeup, due to mutations. Two distinct strains, one identified in Europe (Type I) and one identified in the United States (Type II), have been characterized. Both strains can be found globally.
During the past 20 years, we’ve greatly improved our understanding of the PRRS virus and how to control it; however, there is still much to learn. Swine industry consolidation in the past 15 years has led to entire production systems being designed around strategies for controlling or eliminating this disease.
This analysis is developed as part of the National PRRS Incidence Project and shows both the change in PRRS incidence over time, as well as the seasonality of PRRS impact (virus incidence most commonly spikes in late fall/early winter).