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Self-harvested shellfish may cause illness, say BCCDC experts

If you’re hoping to dig for clams this weekend, be vigilant—warm weather can lead to higher risk of shellfish poisoning.
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The BC Centre for Disease Control is warning the public that there is an increased risk of illness associated with harvesting shellfish such as oysters, clams, mussels, scallops, and other animals such as crabs. Shellfish can accumulate toxins in seawater that can cause paralytic shellfish poisoning, amnesic shellfish poisoning or diarrhetic shellfish poisoning. 

“It’s important to remember that even cooking does not destroy these toxins, and that the shellfish won’t look or smell spoiled,” said Lorraine McIntyre, a food safety specialist at the BCCDC. “The best way reduce your risk is to make sure the area you’re harvesting from is open, harvest when the tide is going out, and keep your shellfish cold.”

Shellfish can also contain viruses such as norovirus, as well as bacteria such as Vibrio parahaemolyticus, which is a greater concern in the summer months. These bacteria are present in higher concentrations when water temperatures are warmer.

In recent weeks, the Poison Control Centre has received calls about illnesses from self-harvested shellfish. Paralytic shellfish poisoning, or PSP, can be serious. Symptoms include tingling and numbness, difficulty breathing, and paralysis. 

Taking the following precautions can reduce the risk of all shellfish-related illnesses.

When self-harvesting:

  • Check whether a shellfish area is open before harvesting.  Call the Department of Fisheries and Oceans toll-free at 1-866-431-3474, or check posted openings and closures online
  • Harvest only on a receding tide.
  • Once you’ve harvested your shellfish, put them into a chilled cooler and keep them cold to prevent bacteria from growing.
When preparing shellfish:

  • Eat only cooked shellfish. Cooking will destroy viruses and bacteria and decrease the risk of gastrointestinal illness. Test oysters with a probe thermometer and make sure the temperature reaches 90°C for 90 seconds.  
  • Do not cook crabs whole.  Split them first and remove the gut contents before boiling them.  This will prevent toxins that may be present from contaminating the muscle flesh.  
  • Keep cooking areas clean.  Separate raw and cooked seafood to prevent cross-contamination, and clean and sanitize knives and cutting boards.  Wash your hands frequently. 
At the first sign of poisoning symptoms, call the Poison Control Centre at 18-800-567-8911. See a physician if your symptoms persist or become severe. You can also call a nurse 24/7 by calling 8-1-1.

Learn more:

BC Centre for Disease Control



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