Amnesic shellfish poisoning

Lore & Background

Amnesic shellfish poisoning was first identified in humans in late 1987 during a serious outbreak of food poisoning in eastern Canada. Three elderly patients died, and other victims suffered long-term neurological problems, particularly memory loss, which gave the condition its name. Epidemiologists from Health Canada linked the illnesses to restaurant meals of cultured mussels harvested from one area in Prince Edward Island, a location never before affected by toxic algae. Mouse bioassays on extracts of the suspect mussels caused death with unusual neurotoxic symptoms distinct from those of paralytic shellfish poisoning and other known toxins. On December 12, 1987, a team of scientists assembled at the National Research Council of Canada laboratory in Halifax, Nova Scotia, and using bioassay-directed fractionation with chemical analysis, identified the toxin on December 16, only four days after the start of the investigation.

Reader's Guide

Amnesic shellfish poisoning represents a significant public health and ecological concern due to its severe neurological effects and increasing incidence. The toxin domoic acid damages the hippocampus and amygdaloid nucleus by overactivating AMPA and kainate receptors, leading to uncontrolled calcium influx and neuronal degeneration. Although human illness has only been associated with shellfish, the toxin can bioaccumulate in other marine organisms such as anchovies and sardines. The incidence of problems associated with toxic algae is generally accepted to be increasing, possibly due to natural mechanisms like currents and tides, as well as human-related factors including nutrient enrichment from agricultural runoff, climate shifts, and transport of algae via ship ballast water. The 1987 Canadian outbreak led to rapid identification of the toxin and established the term 'amnesic shellfish poisoning.' The condition has also been linked to unusual animal behavior, such as a 2006 incident where a California brown pelican possibly under the influence of domoic acid flew through a car windshield, and may have caused a 1961 invasion of frantic seabirds in Capitola and Santa Cruz, California, which inspired Alfred Hitchcock's film 'The Birds.'

Did You Know?

• The toxin domoic acid is produced naturally by marine diatoms of the genus Pseudo-nitzschia and the species Nitzschia navis-varingica.
• In the brain, domoic acid especially damages the hippocampus and amygdaloid nucleus by activating AMPA and kainate receptors, causing an influx of calcium.
• The first human outbreak of amnesic shellfish poisoning occurred in eastern Canada in late 1987, with three elderly patients dying and others suffering long-term neurological problems.
• A 1961 invasion of thousands of frantic seabirds in Capitola and Santa Cruz, California, may have been caused by domoic acid poisoning, and director Alfred Hitchcock used news reports as research for his film 'The Birds.