Porcine epidemic diarrhoea virus in the USA: Lessons learned from the 2013 outbreak

Porcine epidemic diarrhoea virus (PEDV) was detected in the USA in May of 2013 and is believed to have come from China. During the US outbreak, signs began with lethargy, vomiting and 12-36 h later a profuse watery diarrhoea in affected herds. Mortality is effectively 100% within 72 h in pigs less than 7 days of age. In pigs greater than 30 kg or 10 weeks of age, only transient diarrhoea, develops with a minor reduction in feed intake but there is a subsequent reduction in feed conversion. In one study median losses from PEDV were 2403 pigs per 1000 sows which represented an approximately 9% reduction of the total annual output of the farm. It appears that the development of lactogenic immunity takes approximately 14 days reach levels to afford protection to piglets. Control methods have focused on rapid exposure of all animals in infected herds and dramatically increasing hygiene. Spread between herds has been by trucks, people, equipment and supplies. Industry structure likely played a key role in the rapid spread of PEDV in the USA.