Biosecurity vs PED
OKOBOJI – Nearly one year into the porcine epidemic diarrhea virus outbreak in the U.S., and now in Canada, there are still unanswered questions.
Producers know, however, that if they want to keep the disease out of their herds, extreme biosecurity measures must be in place both on the farm and while transporting pigs.
PED virus is a coronavirus similar to transmissible gastroenteritis.
The PED virus can affect pigs of all ages and causes severe diarrhea, with nearly 100 percent death loss in pre-weaned pigs, said Darin Madsen, of the Iowa State University Diagnostic Lab.
The virus renders them unable to absorb nutrients, so dehydration and diarrhea set in. There have been two strains identified, with a possible third being a deltacoronavirus, which has not been fully researched.
Mortality from dehydration in neonate pigs is about 50 percent, but after two weeks of age that number can be reduced significantly.
Madsen said producers can’t determine their herd is infected with PED virus just because they are vomiting. He said pigs need to be tested for it.
Madsen said PED virus can still be present in feces up to 14 days after diarrhea has stopped. He added the disease is known to be intestinal in nature, but there are reports that other tissues could be infected as well. Additional research needs to be done to prove that.
Speaking at a one-day swine conference at Okoboji, Madsen showed that there have been 3,528 new U.S. cases confirmed since the outbreak occurred in April 2013. Canada shows PED virus-infected herds in Ontario and are suspected in Manitoba and Prince Edward Island. Asian countries have been affected by the coronavirus for most of the last two decades.
Madsen said PED virus is only infectious to swine, and, at this point is not to humans or other species.
“We don’t think it’s air transmittable. There’s no proof of that yet,” said Madsen.
Transmission of the disease happens faster in cool weather because the enveloped properties of the virus stay intact in cooler weather, and he said transmission is most commonly done via oral contact with infected fecal matter.
Madsen said a common carrier of the PED virus are truck trailers that carry pigs, and he encouraged producers to be meticulous when it comes to washing trailers.
“The virus is killed by most disinfectants,” he said, adding that such biosecurity measures will go a long way toward keeping the virus from spreading.
He added that transporting show pigs has most likely been one contributing factor in spreading the disease to other states, since producers will drive their stock as far as a few states away to sell it.
The good news comes in the fact that the virus is from only one serotype – meaning that antibodies against PED will be effective against most PED strains – unlike PRRS, which needed various vaccines.
However, he said, vaccine production for the PED virus has been difficult because the disease immunity has to be understood in order to make the vaccine work. That will be difficult because the process to allow that to happen is complicated.
“That’s why none of the TGE vaccines ever worked,” Madsen said, “and it will be the same for PED.”
Madsen said ISU research showed viral shedding went on two weeks after the clinical signs of PEDV had stopped. In a boar study done at ISU, adult animals can do this up to 35 days.
Reinfection data for sow farms show nothing stating that the farms which did a good job of feedback eliminated the signs of PED and the ones that didn’t entered the endemic phase. But Madsen said researchers at ISU re-infected some pigs known to be negative, at 77 days after the first infection.
“They did get infected,” he said, “but for only two days. There was no diarrhea, they did shed the virus for two to three days and that was it.
Madsen said oral fluids can detect the virus just as effectively as fecal inspection. He said he’s not seen any hardcore data that proves feed sources are a transmitter of the PED virus, though could have the potential to be a risk factor.
Madsen said the bottom line – with the little certain information known – is that pig trailers must be washed with disinfectant regularly to help prevent the virus spread.
Research is still being conducted on the ways PED virus reached the United States, after being an issue in Asia for 20 years, Madsen said.
The swine conference was sponsored by ISU Extension, University of Minnesota Extension, Hubbard Feeds and Elanco.
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