Porcine epidemic diarrhea: A retrospect from Europe and matters of debate

A retrospect is given on the emergence of porcine epidemic diarrhea (PED) during the early seventies inEurope. While, at first, it appeared as a disease affecting feeder pigs, fattening- and adult swine, it lateralso became pathogenic for neonatal and suckling pigs hereby drastically increasing its economic impact.Isolation of the causative virus revealed a new porcine coronavirus, the origin of which has never beenclarified. Pathogenesis studies with the prototype strain CV777 showed severe villous atrophy in neonatalpigs and the virus-animal interactions showed many similarities with transmissible gastro-enteritis virus(TGEV), another porcine coronavirus. Disease patterns in field outbreaks showed muchvariation but,while farm related factors played a role, possible genetic variations of virus strains in Europe have notbeen examined and are thus unknown. CV777 in experimental pigs caused diarrheal disease and mortalityrates similar to those later encountered in Asia and more recently with the “original” US strains eventhough genomic typing of the prototype European strain have shown that it belongs to the S-INDELstrains. In Europe, PED has become endemic during the eighties and nineties and subsequently regressedso that, after 2000, swine populations in many countries have largely become seronegative. Sporadicoutbreaks have recently reappeared showing a large variety of clinical outcomes.