Puffer poisoning deaths

The puffer fish is probably the best known neurotoxic fish. Several related species of fish, as well as other marine life, such as some frogs, starfish, octopus, and others, contain tetrodotoxin. Many people consider this fish a delicacy despite the occasional death from poor preparation. Tetrodotoxin is heat stable but water soluble, so careful preparation is necessary to limit neurological effects. Symptoms of poisoning include a rapid onset of numbness in the lips and mouth, which then extends to the fingers and toes, followed by general weakness, dizziness, and respiratory failure, leading to death. The mechanism of action is similar to that of saxitoxin and affects sodium channel permeability. 

Many fish species, over 700 species worldwide, are either directly toxic or upon ingestion are poisonous to humans. A classic example is the toxin produced by the puffer fishes (Sphaeroides spp.) called tetrodotoxin (TTX). Tetrodotoxin is concentrated in the gonads, liver, intestine, and skin, and poisonings occurs most frequently in Japan and other Asian countries where the flesh, considered a delicacy, is eaten as fugu. Death occurs within 5 to 30 minutes and the fatality rate is about 60%. TTX is an inhibitor of the voltage-sensitive Na channel (like saxitoxin) it may also be found in some salamanders and may be bacterial in origin. 

Tetrodotoxin, a complex natural product containing several six-membered rings joined together, is a poison isolated from the ovaries and liver of the puffer fish, so named because the fish inflates itself into a ball when alarmed. Eating fish tainted with trace amounts of this potent toxin results in weakness, paralysis, and eventually death. One step in the synthesis of tetrodotoxin involves forming a six-membered ring by a Diels-Alder reaction. 

Recently, several poisoning cases due to ingestion of, in addition to those of puffers, big and small gastropods have caused in Japan, Taiwan, and China. Especially small gastropods in China have caused many poisoning for a long time, resulting in many deaths and caused serious problems in public health. 

On the other hand, to ensure the safety of consumers in some other Asian countries where the puffer consumption has been increasing, a comprehensive toxicological study should be carried out to identify the toxic and nontoxic puffer fish. On the basis of the results, consumer awareness should be created through several media in order to reduce the poisoning cases. In Japan, as described before, the death number decreases to less than one order although food poisoning cases occur every year. 

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