Protecting Shellfish Health: RPC’s Role in Diagnosing MSX, Dermo and SSO

Written By Amy Brown

Shellfish play an important role in Atlantic Canada’s coastal ecosystems and economies. Like other marine organisms, they are susceptible to disease, and one of the more serious threats to oyster populations is MSX (Multinucleated Sphere Unknown), a parasitic condition caused by Haplosporidium nelsoni.

RPC provides diagnostic testing for MSX, along with other notable shellfish pathogens including Dermo (Perkinsus marinus) and SSO (Haplosporidium costale). These services support aquaculture operations, regulatory agencies, and research initiatives focused on shellfish health and disease management.

Understanding MSX

MSX primarily affects Eastern oysters (Crassostrea virginica) and has been associated with significant mortality in infected populations, particularly in warmer waters. While not harmful to humans, its impact on oyster health can be substantial, influencing both wild stocks and farmed operations.

The disease was first detected in Canada in 2002; however, no further detections were reported through provincial surveillance programs until July 2024, when new cases were identified in Prince Edward Island and New Brunswick (DFO, 2024).

Diagnostic Capabilities at RPC

RPC uses molecular tools such as Multiplex Real Time Quantitative PCR (qPCR) to detect MSX, Dermo, and SSO from a single sample. This approach enables:

  • Early detection of infections

  • Simultaneous screening for 3 targeted pathogens

  • Support for surveillance and management programs

Singleplex and Duplex qPCR options are also available for targeted testing, depending on the specific needs of clients.

Sample Submission Guidelines

RPC accepts both whole organisms and tissue sections for diagnostic testing. If your site is located within a Primary Control Zone (PCZ), a permit issued by Fisheries and Oceans Canada (DFO) is required for sample movement. Submission options include:

  • Live/dead oysters shipped in insulated leak proof containers with ice packs

  • Tissue samples preserved in 95% ethanol for DNA extraction

Guidance is available to ensure proper targeted tissue sections are sampled and stored safely.

RPC’s Role in Shellfish Health Monitoring

With extensive experience in aquatic diagnostics, RPC contributes to shellfish health monitoring through accurate, timely testing and data generation. Our Fredericton-based laboratory is equipped with advanced molecular tools and staffed by professionals familiar with the needs of Atlantic Canada’s aquaculture and fisheries sectors.

Learn More

For more information about RPC’s shellfish health diagnostics, visit https://www.rpc.ca/shellfishhealthdiagnostics or contact us at info@rpc.ca.

Amy Brown https://rpc.ca
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