An outbreak of tetrodotoxin poisoning following gastropod mollusc consumption

Tetrodotoxin, a violent neurotoxin, is present in puffer fish and may occur in a variety of marine animals. Outbreaks of human tetrodotoxin poisoning, following consumption of marine organisms other than puffer fish, has been rare. We here report an outbreak of tetrodotoxin poisoning following ingestion of gastropod molluscs and its clinical features are discussed. A 71-year-old woman was admitted with hypertension and other neurological symptoms developing after ingestion of some molluscs. A further 16 cases were also found to have typical symptoms of tetrodotoxication after mollusc consumption. Clinical features in these 17 cases were similar to those conventionally found in tetrodotoxin poisoning, except that there was hypertension in eight cases (47%). All except one case had mild poisoning and recovered well. The molluscs consumed comprised two different species: Nassarius castus and Nassarius conoidalis, both of which were shown to contain various amounts of tetrodotoxin. It is concluded that tetrodotoxin poisoning following mollusc consumption is a possibility. Hypertension, as an unusual feature in tetrodotoxication, is frequent in this outbreak, and should be looked for in future cases. The explanation of hypertension in tetrodotoxication may come either from an exaggerated response to sympathetic stimuli, or due to various responses of the vasomotor centre to a small dose of tetrodotoxin. Further studies are required to answer this question.