Azaspiracids (AZA) are a group of polycyclic ether marine algal toxins produced by the small dinoflagellate Azadinium spinosum that can accumulate in shellfish and thereby cause illness in humans.

Similar to DSP toxins, human consumption of AZA-contaminated shellfish can result in severe acute symptoms that include nausea, vomiting, diarrhea, and stomach cramps.

[3][28][29] The absence of known DSP toxins okadaic acid and dinophysistoxin-2 led to the discovery and identification of a novel etiological agent, temporarily called Killary Toxin-3 before being renamed to AZA1.

Analysis of the shellfish revealed five AZA analogues, AZA1-5, with most of the toxin concentrated in the digestive glands[8][9] at levels exceeding 30 μg/g (estimated at 6 μg/g whole mussel meat).

[citation needed] In September 1998, mussels exported from Clew Bay, Ireland to Ravenna, Italy were consumed and ten people fell victim to AZP with typical gastrointestinal symptoms.

[citation needed] Also in September 1998, a large shipment of mussels from Bantry Bay, Ireland was sent to France, resulting in an estimated 20-30 human illnesses due to AZP.

[citation needed] In August 2000, between 12-16 people from various regions (Warrington, Alyesbury, Isle of Wight, Sheffield) of the United Kingdom were intoxicated following the consumption of frozen, pre-cooked mussels that originated from Bantry Bay, Ireland.

These mussels were also deemed safe for human consumption based on results from mouse bioassays; however, LC/MS analysis determined the presence of AZA1-3 in an uneaten portion from this same batch.

[32][33] The purported synthesized AZA1 structure was found to have a different chromatographic behavior and discrepancies in its nuclear magnetic resonance (NMR) spectrum compared to the compound isolated from natural sources.