Perkinsus marinus is not a risk to food safety or human health.
On this page
- Impact on oysters
- Susceptibility
- Clinical signs
- Diagnosis and treatment
- Transmission and spread
- Disease management
- Preventative measures
Impact on oysters
Perkinsus marinus can kill oysters and it usually infects them between 1 and 3 years of age. Mortality rates vary but are typically 50% to 75%.
Susceptibility
Species susceptible to Perkinsus marinus in Canada's natural environment include:
- Crassostrea virginica (American oyster)
Species susceptible to Perkinsus marinus not in Canada's natural environment include:
- Crassostrea ariakensis (Suminoe oyster)
- Crassostrea corteziensis (Cortez oyster)
- Saccrostea palmula (Palmate oyster)
Clinical signs
Perkinsus marinus causes Dermo disease in molluscs, which typically becomes clinically apparent in adult oysters that are more than 1 year of age. Infection with Perkinsus marinus is a chronic disease. Infected molluscs may show the following signs:
- behaviour
- gaping (shells are open when out of the water)
- no active feeding
- appearance
- shell valves are slow to close when molluscs are disturbed or removed from the water
- pale appearance of the digestive gland
- small mantle
- decreased growth and variation in size of animals typically begins to increase a few months prior to mortality
Susceptible species with the disease may show 1 or more of these signs; however, the disease may still be present even if no signs are observed.
Diagnosis and treatment
Not all infected oysters show signs of disease. Infection with this parasite can only be diagnosed through lab testing.
There is no treatment for Perkinsus marinus.
Transmission and spread
Perkinsus marinus is spread by the movement of:
- infected oysters
- contaminated water
- contaminated equipment
Disease management
Perkinsus marinus is a reportable disease in Canada. This means that anyone who owns or works with aquatic animals and knows of or suspects Perkinsus marinus in their molluscs, is required by law to notify us.
We have several programs in place to prevent the spread of this disease. This includes the Domestic Movement Control Program (DMCP), as well as responding to and investigating all suspected cases of Perkinsus marinus reported to us.
The following watersheds are declared infected for Perkinsus marinus:
- Atlantic Ocean
- New Brunswick
- Newfoundland and Labrador
- Nova Scotia
- Prince Edward Island
- Quebec
Confirmed cases of federally reportable aquatic animal diseases in Canada, like Perkinsus marinus, are reported monthly on our website.
Dermo is a World Organization for Animal Health (WOAH) listed disease.
Preventative measures
If you handle or work with oysters, we recommend the following precautions.
Do not import live molluscs or mollusc products into Canada without proper permissions
You might need an aquatic animal health import permit, zoosanitary certificate or other documentation to import aquatic animals into Canada. Consult the susceptible species of aquatic animals for guidance on import requirements.
You must follow the import permit conditions to prevent the introduction and spread of diseases. You can learn more on import requirements and countries approved to export to Canada in the Automated Import Reference System (AIRS).
Before bringing molluscs into Canada, check all federal and provincial or territorial requirements.
Do not introduce live molluscs or mollusc products from another country into the natural waters of Canada without proper permissions
People releasing molluscs into the natural waters or rearing facilities within Canada should check if federal, provincial, or territorial permissions are required.
Information on our import requirements can be found in the AIRS.
Do not use oysters as bait
Do not use molluscs that were bought in a grocery store as bait for catching fish or other aquatic animals.
Wash and disinfect gear and equipment
Wash and disinfect any gear you wore (for example, footwear, gloves, waders, etc.) after being on-site or handling oysters. Thoroughly wash and disinfect your gear (for example, tongs, cages, bins, etc.) and air dry them.
Take precautions after travelling
We recommend that you do not visit Canadian aquaculture sites, zoos or aquariums for 14 days if you have travelled to another country and visited an aquaculture site or had contact with molluscs.