Porcine reproductive and respiratory syndrome (PRRS) is characterized by reproductive failure of sows and respiratory problems of piglets and growing pigs.
The disease is caused by PRRS virus, currently classified as a member of family Arteriviridae, genus Arterivirus. The primary target cell of the virus is alveolar macrophage of pigs. Two major types of the virus exist, the European (EU) and the North America (NA) strain. The virus is primarily transmitted by contaminated feces, urine, semen and infected pigs. High level of sanitary management system is required because fomite infection is also possible.