Alberta PED test shows value of vigilant surveillance: expert

Alberta veterinary epidemiologist Julia Keenliside says zero is her favourite number. That is the number of porcine epidemic diarrhea cases found in Alberta pigs.

On Aug. 2, ongoing surveillance testing turned up PED on a livestock trailer, causing concern that the deadly virus had arrived in Alberta.

Keenliside said no pigs in the province have the disease, but the test showed the need for constant vigilance.

“We often say in surveillance that zeroes are good. As an epidemiologist, I love to see zeroes because it means we don’t have diseases and I think this shows the value of surveillance.”

PED virus is almost always fatal to young piglets. It has been found in four provinces, and most of the cases are in Ontario and Quebec. Manitoba has had 10 premises affected, and Prince Edward Island has had one.

The virus has also killed millions of piglets in the United States since it was first identified there in 2013.

Saskatchewan, British Columbia and Alberta remain free of PED infection in pigs, and surveillance testing and biosecurity on hog farms are needed to keep it that way, Keenliside said.

The Aug. 2 positive test was the first time PED had been found on a livestock trailer.

One other test, in 2014, found signs of it in an office. However, a positive test on surfaces does not mean infection of pigs.

“The detection of the virus on a truck was done by a PCR (polymerase chain reaction) test, and as you recall, PCR only detects the protein from the virus and doesn’t tell us if the virus is alive or dead. It only tells us that the virus was once there and it might still be there,” said Keenliside.

“It is a warning that the virus was there on this particular trailer.”

The trailer in question was used to deliver cull sows from Manitoba to the United States in late July. It was washed in Wisconsin before returning to Canada.

It then picked up a load of equipment unrelated to livestock and delivered it to Alberta.

Keenliside said once the test showed evidence of PED on the trailer, the trailer was washed, disinfected, dried and retested to ensure it was free of the virus.

“It’s really good to know that our transporters and our truck washes have their protocols in place in order to deal with this,” she said.

“They took it very seriously and did their utmost to ensure the trailer was clean before it went back into use again.”

She said that of the six swabs taken from the trailer for PCR testing, only one was positive and it was not a very strong positive at that.

Saskatchewan has had several positive PED tests on trailers in the past two years, as has Manitoba, where four hog barns were infected with the virus earlier this year.

The most recent case of barn infection there was June 4.

“We know that Manitoba has a lot of trucks directly going to and from the U.S. both with cull sows and isowean pigs,” said Keenliside.

“Saskatchewan has fewer trucks, but they’re more closely connected to that U.S. border crossing,” she said.

“Here we’re a lot more isolated because a lot of trucks that come here get washed in Manitoba first.”

Evidence of PED in Alberta, as shown through the positive tests, are a reminder to hog producers that strict biosecurity and vigilance are needed to protect their pigs and their business operations, Keenliside said.

Alberta and Saskatchewan pigs remain free of PED virus, but “I don’t think for a minute we should get complacent.… In fact, the opposite is true. These diseases are quite the risk for us.”

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