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