Update on porcine epidemic diarrhea

orcine epidemic diarrhea virus (PEDV), a member of the Coronaviridae, is antigenically distinguishable from the other porcine coronaviruses, transmissible gastroenteritis virus (TGEV), and hemagglutinating encephalomyelitis virus (HEV).1,2,3 Diarrhea caused by PEDV is clinically difficult to distinguish from diarrhea caused by infection with TGEV.4,5 Transmissible gastroenteritis (TGE)-like outbreaks of acute diarrhea were first reported in feeder and grower pigs in England in 1971, but TGEV and other known enteropathogenic agents were ruled out as the cause. 6During these outbreaks, suckling pigs (less than 4 to 5 weeks of age) did not become sick.In 1976, other European countries reported similar disease outbreaks in pigs of all ages, including suckling pigs.4,7,8 The disease was named "epidemic viral diarrhea" (EVD) and the designates EVD type 1 (EVD1) and EVD type 2 (EVD2) were used to differentiate between the earlier outbreaks and those affecting pigs of all ages.7,8 In 1978, a coronavirus-like agent was demonstrated as the causative agent of EVD2 and probably the cause of EVD1 outbreaks, and the name "porcine epidemic diarrhea" "(PED)" was proposed.7,8 The reason for the different clinical presentations of EVD1 and EVD2 remains unknown.Since then, the disease has been recognized in a number of European countries, and more recently in China, Korea, and Japan.5,[9][10][11][12][13] In recent years, acute outbreaks have become rare in regions where the virus is widespread.Presently in Europe, diarrhea due to PEDV is most often seen in feeder and grower pigs and in young breeding animals, whereas suckling piglets are rarely affected.In Asia, however, severe epizootics with high mortality still occur in swine of all ages, and these outbreaks cannot be differentiated clinically from acute TGE.5,12,13 Editor's note: This article is the fourth in a series dedicated to foreign animal diseases.Although US swine veterinarians are unlikely to see these diseases in practice, awareness is vital to early detection.