ABSTRACT
About 100 species of puffer fish use the powerful tetrodotoxin to discourage consumption by predators. Tetrodotoxin is found in all organs of the fish but is highest in liver, skin, and intestine. The origins of the toxin are not clear, but one possibility is that the fish come in contact with bacteria that produce tetrodotoxin. Puffer fish may also have elevated levels of saxitoxin, a neurotoxin responsible for paralysis in shellfish poisoning. Saxitoxin is produced by dinoflagellates (algae) and most often contaminates mussels, clams, and scallops. Both saxitoxin and tetrodotoxin are heat stable so cooking does not reduce toxicity. Tetrodotoxin causes paralysis by affecting sodium ion transport in both the central and peripheral nervous system. A low dose of tetrodotoxin produces tingling sensations and numbness around the mouth, fingers, and toes. Higher doses produce nausea, vomiting, respiratory failure, difficulty walking, extensive paralysis, and death. As little as 1 to 4 mg of the toxin can kill an adult. Saxitoxin has a very different chemical structure to tetrodotoxin, but similar effects on transport of cellular sodium; it produces similar neurological effects, but is less toxic that tetrodotoxin. Some people, particularly in Asia, consider the puffer fish a fine delicacy providing it is carefully prepared by experienced chiefs. The trick is to get just a small dose to feel mild tingling effects but not the more serious effects of the tetrodotoxin. In the United States tetrodotoxin poisoning is rare, but a recent report by the US CDC described several case studies of people catching and consuming puffer fish containing elevated levels of these toxins and suffering the ill effects (MMWR, 2002).
