Question Period Note: MSX AND DERMO IN ATLANTIC CANADA

Q1 – What measures has the Government of Canada put in place to address the issue of MSX in Oysters from the Atlantic? Q2 – Does the Canadian Food Inspection Agency monitor for MSX and Dermo? Q3 – Does MSX or Dermo pose a health risk to humans? Q4 – What will the long-term impacts be on the oyster industry?

R.1 - Due to the widespread detections of MSX within oyster populations around Prince Edward Island, and the high volume of oyster movements in Atlantic Canada, the Canadian Food Inspection Agency has moved from Primary Control Zones to the Domestic Movement Control Program as Prince Edward Island is considered a declared area for MSX as of February 7, 2025. The Domestic Movement Control Program allows industry to operate without additional permitting requirements and prevents oysters from Prince Edward Island from entering waters where MSX has not been detected.

The Canadian Food Inspection Agency continues to engage industry by providing biosecurity advice and is working collaboratively with provinces to protect oyster health through its advisory role as part of the Introduction and Transfer Committee.

Additionally, for the other Atlantic provinces where MSX has been detected, response measures include:

• applying movement controls to oysters in specific Nova Scotia and New Brunswick areas;
• further investigating the potential source of the detection;
• engaging scientists, producers and harvesters to continue to monitor mollusc health, including notifying the Canadian Food Inspection Agency or Provinces of sick oysters or when decreased rates of growth or increased mortalities are observed; and
• ensuring that information regarding detection and movement control information is available to producers. R.2 - Through mandatory notifications, the Canadian Food Inspection Agency maintains real-time awareness of MSX and Dermo in all Canadian waters and responds to notifications according to our World Organisation for Animal Health obligations. The Canadian Food Inspection Agency leads this program with the support of the Department of Fisheries and Oceans Canada and Provincial Governments.

Canada Food Inspection Agency

• MSX and Dermo are reportable diseases in Canada. The Canadian Food Inspection Agency is the Competent Authority for aquatic animal health in Canada and responsible for developing disease response plans
• The goal is to prevent further spread of MSX/Dermo within Canada through surveillance, sampling and disease response which includes:
o Quarantine
o Primary Control Zones
o Permits for movement controls of animals and equipment that could spread the disease in or out of the Primary Control Zones
o Declared areas for MSX/Dermo

Fisheries and Oceans Canada

• Unique to Prince Edward Island, Fisheries and Oceans Canada manages shellfish aquaculture issuing and managing leaseholds on provincial seabed where shellfish aquaculture takes place.
• Fisheries and Oceans Canada is the lead in supporting and conducting research on reportable aquatic animal diseases – and provides funding to support research.
• Fisheries and Oceans Canada provides science support and laboratory diagnostic services.
• Fisheries and Oceans Canada also provides, at a local level and with the province, information pertaining to known oyster movements and historical trends in oyster culture and harvest practices.

Provincial Governments

• Key partner in engaging Industry.
• Intimate knowledge of industry needs and practices.
• Oversight of a shellfish health program (provincial mandate).
• Support industry through monitoring and sharing of information, through the prevalence trends of MSX in their waters and using it as part of the decision tree for proposed oyster movements.
• Management of endemic diseases within their provincial boundaries.

R.3 - This disease poses no risk to human health, nor does it pose a risk to food safety. R.4 - Control measures have been put in place to limit the spread of the disease. A permitting process has been established to allow industry activities to proceed under specific conditions. This includes permitting the movement of oysters to domestic and international markets. The long-term impacts are not clearly understood at this time; however, the Government of Canada departments and agencies are collaborating to ensure the proper supports are in place to aid the oyster industry in its recovery.

The Department of Fisheries and Oceans has made funding available to support scientific research into the disease and into finding resistant species.
 

MSX and Dermo are reportable disease in Canada according to the Health of Animals Act. Not all infected oysters show signs of disease. Diagnosis of an MSX and Dermo infections requires the identification of the disease through laboratory testing.

Multinucleate sphere unknown (MSX) is a serious disease of American oysters (Crassostrea virginica) that can cause significant mortality (up to 90-95%) and reduces the production and harvest of both cultured and wild oysters. It is impossible to eliminate MSX once found in the marine environment and the full life cycle of the parasite, including the intermediate host, remains unknown. While MSX prevents oysters from thriving, this disease is not a food safety concern as it poses no risk to human health and oysters remain safe to consume.

The economic impact of MSX is considerable. In 2023, oyster aquaculture in Canada was valued at $66 million—making it the most valuable shellfish sector in the country.

In July 2024, the Canadian Food Inspection Agency (CFIA) confirmed the presence of MSX in oyster samples collected in Bedeque Bay, Prince Edward Island (PEI). Subsequently, the presence of MSX was confirmed in New Brunswick in November 2024. MSX has been present in the Cape Breton East area of Nova Scotia since the early 2000s. To date, MSX has not been detected in Newfoundland and Labrador.

On February 7, 2025, the province of PEI was declared as an area where MSX is known or is highly likely to occur. The Domestic Movement Control Program allows industry to operate without additional permitting requirements and prevents oysters from PEI from entering waters where MSX has not been detected.

Perkinsus marinus (Dermo) is also a serious disease of American oysters (Crassostrea virginica) and is commonly found in populations of oysters that have MSX. Mortality rates are lower than MSX (can be up to 50-60%), but it restricts production of wild and cultured oysters at a younger age than MSX. It is impossible to eliminate Dermo once found in the marine environment and it is transmitted directly between oysters. Dermo poses no health risks to humans and Atlantic Canadian oysters are safe to consume.

In November 2024, the presence of Dermo was officially confirmed in New Brunswick for the first time in Canada. It was subsequently confirmed in Nova Scotia later that month and was confirmed in Newfoundland and Labrador on May 29, 2025.

To prevent the spread of Dermo in Canada, the CFIA has established primary control zones (PCZs) in areas where the disease has been detected or is suspected to exist. Dermo has been detected in three Atlantic provinces (New Brunswick, Nova Scotia, Newfoundland and Labrador) and a suspect detection in PEI.

• MSX and Dermo do not pose a threat to food safety.

• MSX and Dermo is having a devastating impact on Canada’s $66 million oyster industry.

• The Government of Canada in collaboration with the impacted provinces are working to ensure the proper supports are in place to aid the oyster industry in its recovery.

• The Canadian Food Inspection Agency is working with Fisheries and Oceans Canada, the provinces and industry to address these outbreaks and to control the spread of the disease.