ABSTRACT

The diarrhetic shellfish poisoning (DSP) toxins belong to three different structural classes: (1) okadaic acid (OA) and its analogues, (2) pectenotoxins, and (3) yessotoxins. Major toxic incidents resulting from the ingestion of shellfish in which the predominant human symptom was diarrhea occurred in Japan in 1976 when 42 people suffered food poisoning after eating mussels from the Sanriku coast. Similar incidents occurred in the Tohoku District in 1977 but with a larger number of intoxications (1) from the ingestion of clams, scallops, and mussels. As no pathogenic microorganisms were found in leftover foods, it was presumed that an unknown toxin was responsible. In Europe, the first report of similar toxic incidents from the ingestion of mussels occurred in the Netherlands, although no toxin was identified (2). The main toxic symptoms were diarrhea (92%), nausea (80%), vomiting (79%), and abdominal pain (53%) and the syndrome was termed diarrhetic shellfish poisoning (DSP). Symptoms occurred between 30 mins to a few hours after shellfish consumption and lasted for a maximum of 3 days. The dinoflagellate Dinophysis fortii was abundant in the marine shellfish cultivation areas in Japan around the time of toxicity, and this was subsequently confirmed to be the toxin-producing organism. The toxin responsible was isolated and identified as 35-methylokadaic acid (3, 4) and was named dinophysistoxin-1 (DTX-1).