Canadian Food Inspection Agency lab tests have confirmed the presence of the highly damaging mollusc disease dermo in oysters from P.E.I.’s Egmont Bay.
“This is the first confirmed case of dermo in P.E.I.,” the agency said in a news release issued Friday evening. “Dermo does not pose a risk to human health or food safety, but it can cause increased oyster mortality and decreased growth rates.”
In a separate email, CFIA also said that tests had confirmed the first cases of both dermo and MSX for the province of Quebec, in oyster samples collected in Chaleur Bay.
It’s been eight months since what was considered the first detection of dermo in Canadian waters, in oysters from Spence Cove, about five kilometres west of the Confederation Bridge in New Brunswick.
Dermo disease or Perkinsosis, caused by a parasite called Perkinsus marinus, had previously been detected in Atlantic waters between Mexico and Maine. It affects both cultured and wild American oysters (Crassostrea virginica).
More than 80 of the Island’s wild oyster harvesters had to find new places to fish after the MSX parasite forced the shutdown of Bedeque Bay last year. As CBC’s Nancy Russell reports, the pressure to find more oysters has meant some rivers are being fished out — and that could mean no catches next spring.
“Outbreaks of Perkinsosis usually occur with warm summer water temperatures above 20 C,” a British government fact sheet on the disease says. “Clinical signs may include pale digestive glands, gaping, shrinking of the mantle away from the outer edge of the shell and stunted growth.”
The CFIA news release said dermo “does not affect other bivalves in this area, including mussels, scallops or clams.”
Already dealing with MSX
News of the positive test results from Egmont Bay will be another blow to the Island’s oyster industry, which has been reeling from last July’s discovery of MSX, short for multinucleate sphere unknown.
That oyster disease was first detected in samples from P.E.I.’s Bedeque Bay, with more cases confirmed in other areas of the province in the months that followed. Like dermo, it affects only oysters and not the humans eating oysters from waters known to have MSX.
The Canadian Food Inspection Agency says the parasite that causes dermo is easily transmitted among oysters, mostly when they are between one and three years of age.
“Mortality rates are variable but are typically 50 per cent to 75 per cent,” the agency says in a factsheet on its website.
CFIA has power to limit movement
In a statement to CBC News last month, the Canadian Food Inspection Agency acknowledged that it had been asked to test P.E.I. oyster samples for dermo, but said it had no results to share at that time.
The agency did go on to outline what would happen if the samples did test positive.
If a product in a PCZ [primary control zone] is deemed to be a potential risk, its movement would be controlled.— Canadian Food Inspection Agency
“To prevent the spread of dermo or any other animal diseases, the CFIA may establish a primary control zone (PCZ) in areas where a disease is suspected to occur,” the statement said.
That kind of move would let the agency control how oysters are handled and shipped within and outside the zone.
“For example, if a product in a PCZ is deemed to be a potential risk, its movement would be controlled; this means that a permit from the CFIA would be required to move this product within, through and outside of the PCZ,” the statement said.
“Any new PCZs would be posted as soon as possible on CFIA’s website. When a new PCZ is put in place, the CFIA also notifies its provincial partners, stakeholders, Indigenous communities and industry through pre-existing communications channels.”
