Canadian Food Inspection Agency
MSX, Dermo Detected in Quebec Oysters
The Canadian Food Inspection Agency (CFIA) has confirmed the presence of the aquatic animal diseases multinucleate sphere unknown (MSX) and Dermo (also known as Perkinsosis) in oyster samples collected in Chaleur Bay, Québec.
MSX and Dermo do not pose risks to human health or food safety, but they can cause increased oyster mortality and decreased growth rates. These are the first confirmed cases of MSX and Dermo in Quebec.
To limit the spread of the diseases, the CFIA, Fisheries and Oceans Canada (DFO) and the province of Quebec are working together with partners to monitor the situation and take necessary action. These actions are part of the Government of Canada’s One Health approach to prepare for, detect, and manage animal diseases.
In addition to existing robust protective measures and increased animal surveillance, the CFIA, in collaboration with DFO and the province of Quebec, continues to conduct tracing activities and testing of oysters to gain insight into the presence of MSX and Dermo in the area.
Response measures include:
Quick Facts
https://www.canada.ca/en/food-inspection-agency/news/2025/07/detections-of-msx-and-dermo-in-oysters-in-quebec.html