Amnesic Shellfish Poisoning

Food Safety October 29, 2010 Print Friendly and PDF


About Amnesic Shellfish Poisoning

An FDA shellfish specialist (left) and an inspector from the New Jersey Department of Health (center) working to ensure the safety of our shellfish.

Amnesic shellfish poisoning is a rare syndrome caused by a toxin made by a microscopic red-brown salt-water plant or diatom called Nitzschia pungens. The toxin produced by these diatoms, domoic acid, is concentrated in some shellfish and causes disease when the contaminated shellfish are eaten.


Patients first experience gastrointestinal distress within 24 hours after eating the contaminated shellfish. Other reported symptoms have included dizziness, headache, disorientation, and permanent or short-term memory loss. In severe poisoning cases, seizures, focal weakness or paralysis, and death may occur.

Foods Associated with Illness

Mussels, clams, oysters, and scallops found in the coastal waters of the Pacific Northwest and the east coast of Canada.

Prevention of Amnesic Shellfish Poisoning

  • Check with local health officials before collecting shellfish.
  • Do not eat shellfish sold as bait. Bait products do not need to meet the same food safety regulations as seafood for human consumption.


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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.