Amnesic shellfish poisoning
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Amnesic shellfish poisoning (ASP) is one of the four recognised syndromes of shellfish poisoning (the others being neurotoxic shellfish poisoning [1], diarrhetic shellfish poisoning [2] and paralytic shellfish poisoning). All four syndromes share some common features and are primarily associated with bivalve mollusks (such as mussels, clams, oysters and scallops). These shellfish are filter feeders and, therefore, accumulate toxins produced by microscopic algae in the form of dinoflagellates and diatoms.
ASP results from consumption of domoic acid. In the brain, domoic acid especially damages the hippocampus and amygdaloid nucleus. It damages the neurons by activating AMPA and kainate receptors, causing an influx of calcium. Although calcium flowing into cells is a normal event, the uncontrolled increase of calcium causes the cell to degenerate.
The chemical can bioaccumulate in marine organisms that feed on the phytoplankton, such as shellfish, anchovies, and sardines. In mammals, including humans, domoic acid acts as a neurotoxin, causing permanent short-term memory loss, brain damage, and death in severe cases. Red tides are associated with the phenomenon of ASP.
[edit] Discovery
ASP was first discovered when, in late 1987, a serious outbreak of food poisoning occurred in eastern Canada. Symptoms of the poisoning included vomiting and diarrhea, followed in some cases by confusion, memory loss, disorientation, and coma. Three elderly patients died and other victims suffered long-term neurological problems. Because of the memory loss problem, the term amnesic shellfish poisoning (ASP) is used to refer to this clinical syndrome [M. A. Quilliam, J. L. C. Wright, Anal. Chem., 61 (1989) 1053A]. The story made front-page newspaper headlines.
Epidemiologists from Health Canada quickly linked the illnesses to restaurant meals of cultured mussels harvested from one area in Prince Edward Island, a place never before affected by toxic algae. Mouse bioassays on aqueous extracts of the suspect mussels caused death with some unusual neurotoxic symptoms very different from those of paralytic shellfish poison and other known toxins. On December 12, 1987, a team of scientists was assembled at the National Research Council of Canada laboratory in Halifax, Nova Scotia. Integrating bioassay-directed fractionation with chemical analysis, the team identified the toxin on the afternoon of December 16, just 4 days after the start of the concerted investigation.
[edit] Possible animal impacts
On June 22, 2006, a California brown pelican, possibly under the influence of domoic acid, flew through the windshield of a car on the Pacific Coast Highway. The acid is found in the local seas.
Domoic acid poisoning was the most likely cause of a 1961 invasion of thousands of frantic seabirds in Santa Cruz, California. Director Alfred Hitchcock heard about this invasion while working on his adaptation of Daphne du Maurier novella "The Birds" for his feature film The Birds (1963).
