False positive means one less confirmed case of PEDv in province

A fifth hog barn once thought to contain the virus that causes PED has been cleared 
after an extensive investigation and further testing

pigs in a barn stall feeding

A fifth farm in Manitoba has not been infected with porcine epidemic diarrhea (PED) after all.

The province had issued a bulletin Oct. 1 indicating a nursery finisher barn had tested positive for the virus, but subsequent tests found no trace of porcine epidemic diarrhea at the farm.

“Really what it comes down to is that no test is ever perfect,” said chief veterinary officer Megan Bergman. “Unfortunately these things do happen.”

An initial sample taken from the farm was tested twice and returned positive results both times. However, further monitoring by both the province and a private veterinarian turned up no signs of PED, a disease that has caused producers across Canada to be on high alert for the last year.

The barn in question had not experienced high rates of mortality as was reported in the Manitoba Co-operator in the Oct. 9 issue and further observations showed no clinical signs of the disease in the herd, officials said. Earlier comments related to high mortality rates related to general effects of the disease on young pigs. Clinical signs of PED include diarrhea, fever, vomiting and piglet deaths.

Since PED monitoring in Manitoba began early this year 1,090 samples from 182 farms have been tested for the virus. Nearly 4,000 samples have also been submitted for testing from high-traffic sites in the province. Eight of those high-traffic sites have tested positive for the virus.

“It’s kind of unexplained as to how that first sample came in positive, we’re not exactly sure how that came about,” said Mark Fynn, an animal care specialist with the Manitoba Pork Council. “Whether there was some cross-contamination at some point not related to the farm, we don’t know. But there are no clinical signs on the farm and no samples from the pigs or from the environment have come up positive now.”

He added that further investigation has shown that the so-called fifth farm was also negative at the time the first sample tested positive.

“We’re doing some investigation and seeing what we can find out, see if we can identify the source of the positive, but at this point we don’t have an answer yet,” said Bergman.

However, four other farms in the province have been confirmed to have the PED virus — two sow barns and two finisher barns, all located in the southeast of the province.

The now-cleared fifth barn is also located in southeastern Manitoba, but outside of the five-km buffer zone around the two sow barns where PED was discovered last month, causing some to take a closer look at the results.

“Because this was outside of the five kilometres, it was another reason for us to go back and take a really close look,” said the chief vet.

The presence of PED can be easier to identify in sow barns, because newborn pigs are most susceptible to the disease. Some sow barns see piglet mortality rates in excess of 80 per cent.

However, adult swine show few clinical signs of the virus.

“Signs in a nursery finisher are pretty subtle,” said Fynn. “Usually you have the herd go through a bout of having some diarrhea for a couple of days and then the pigs are back to normal — they recover pretty well and you don’t see any increase in mortality or anything like that.”

But better to have a false positive than a false negative he said, adding he believes the protocols for detecting the disease in the province are working well.

Producers are reminded to stay vigilant when it comes to biosecurity protocols, but there is relief that the number of confirmed on-farm cases remains at four, not five.

“It’s back to business for this farm now,” Bergman said. “We’ve done some really extensive followup… and because we’re not seeing any clinical signs and there are no positive results we’re confident that the farm is negative.”

About the author

Reporter

Shannon VanRaes is a journalist and photojournalist at the Manitoba Co-operator. She also writes a weekly urban affairs column for Metro Winnipeg, and has previously reported for the Winnipeg Sun, Outwords Magazine and the Portage Daily Graphic.

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