The porcine epidemic diarrhea (PED) virus that devastated the US swine industry several years ago continues to persist, causing fewer pig deaths but curtailing pig growth.
“Some [farms] have been successful in eliminating PED from sow farms, but maybe not completely from farrow to finish,” reported Gene Nemechek, DVM, technical service, Zoetis.
“Although PED can continue to infect nurseries and finishing without killing a lot of pigs, it will set back [surviving pigs],” he added.
“Producers are going to have to try to decide whether they can eliminate [PED] and keep it out of their farms, or maybe live with it through inoculation of gilts or through vaccination programs,” he told Pig Health Today.
When weighing the option to eliminate PED, producers must scrutinize biosecurity practices.
“It’s really, can they prevent dragging [PED] back into the sow farms through biosecurity practices?” Nemechek said. “There are so many ways people can make a mistake.”
In pig-dense areas, the virus tends to circulate in finishing sites where there are plenty of places for contamination: truck washes, trailers, people. Plus, the virus lives longer in colder areas, increasing the risk of tracking it into a sow farm.
“When you have people coming and going into large sow units…multiple people entering every day, the opportunity is there for something to come in,” he added. “It might only be one chance in 100, but that’s all it needs.”
Feed is another biosecurity risk. PED can be spread through contaminated feed and feed byproducts as well as on the trucks and drivers transporting feed to the farms.
Managing herd immunity
Where PED elimination is not possible, inoculation of gilts with the virus or vaccination programs with a conditionally licensed vaccine will help manage herd immunity.
“The biggest thing is inoculating gilts and getting them exposed to PED before entering the sow farm,” Nemechek said. “Of course, that immunity doesn’t appear to be life-long so an older-sow farm could become exposed to the virus and show clinical signs…So vaccines can help in those cases.
“I think we’ve made some good progress [against PED],” he added. “We probably could make some improvements with preventative measures, maybe some with vaccines.
“And as an industry, we…haven’t put our heads together and decided what we need to do long term — either to eliminate it or live with it.”