Amnesic Shellfish Poisoning

Causative organisms: Pseudo-nitzschia spp.

Toxin produced: Domoic Acid

Amnesic Shellfish Poisoning (ASP) can be a life-threatening syndrome that is characterized by both gastrointestinal and neurological disorders. Gastroenteritis usually develops within 24 hours of the consumption of toxic shellfish; symptoms include nausea, vomiting, abdominal cramps, and diarrhea. In severe cases, neurological symptoms also appear, usually within 48 hours of toxic shellfish consumption. These symptoms include dizziness, headache, seizures, disorientation, short-term memory loss, respiratory difficulty, and coma. In 1987, four victims died after consuming toxic mussels from Prince Edward Island, Canada. After that incident  Canadian authorities began monitoring the water column for the presence of the causative diatom and shellfish for the presence of the toxin, domoic acid. Shellfish beds are closed to harvesting when the domoic acid concentration reaches 20 µg/g shellfish meat. However, since fish and crab viscera can also contain domoic acid, the risk to human consumers and animals in the marine food chain is more significant than previously believed.

U.S. Finfish, Shellfish and Wildlife Affected by ASP
Harmful Algal Species
Geographic Area
Affected Organisms*
Pseudo-nitzschia pungens f. multiseries Gulf of Maine
Puget Sound, WA
Bay scallops+
Sea scallops+
P. australis California Anchovies
Sea birds
P. australis Washington
Dungeness crabs+

*Found to contain algal toxins, or to be adversely affected by toxic or harmful marine algae.
+Causative algae implicated, not confirmed.

Medical Community
ASPAmnesic Shellfish Poisoning
Additional Information on ASP including: Background, Clinical Presentation, Diagnosis, Management and Treatment, Chemical Structure, and Molecular Mechanism of Action.

Last updated: July 31, 2012