An epidemic of tetrodotoxin poisoning following ingestion of the horseshoe crab Carcinoscorpius rotundicauda.

At certain seasons of the year in Thailand, the horseshoe crab Carcinoscorpius rotundicauda may be toxic to human and fatal poisoning occasionally occur. Tetrodotoxin (TTX) and its derivatives were major toxins in the toxic eggs of the horseshoe crab. An epidemic of poisoning by eating toxic eggs of the horseshoe crab affected 71 persons in Chon Buri which located in the eastern coast of Thailand. Patients generally presented with neurologic symptoms such as paresthesia, vertigo, weakness, respiratory paralysis, altered consciousness with unreactive dilated pupils in addition to gastrointestinal symptoms such as nausea and vomiting. Nineteen patients required artificial ventilation and there were two deaths. This is the first large outbreak of tetrodotoxin poisoning recognized in Thailand.