Chapter 2- The Diving Environment The Diving Environment 53 gellate (Gambierdiscus toxicus) that generates the toxins finds itself in the food chain of many species of fish. The toxin does not seem to affect the fish, who eventually concentrate the material in their tissues and become poisonous to man. Generally, the larger the fish, the more toxic it can be. Symptoms usually develop 6 to 12 hours after eating the fish, but in some cases they may show within one hour after ingestion. The first signs of illness are usually gastrointestinal in nature: nausea, vomiting, cramps, and diarrhea. These are soon followed by neurological symptoms such as tiredness, itching, pain or weakness in the legs, painful joints (arthralgia), numbness around the mouth, hot and cold reversal of sensation, headache, muscle ache, chills, watery eyes, dizziness, tremor, sweating, and a red rash. Clinical signs vary from minor complaints to coma and death. With proper and prompt diagnosis, this can effectively be treated with drugs by a physician. Consumption of fish such as barracuda (sphyraeniadae), grouper (serranidae), red snapper (Lutjanus bohor), amberjack (Seriola dumerili), and surgeonfish (acanthuridae) can all transmit ciguatoxin. Eating any affected fish, whether it is cooked or raw, may result in poisoning. Another ichthyosarcotoxism is scombroid poisoning, which the Hawaiians refer to as mahi mahi (dolphinfish) flushing syndrome or saurine poisoning. Scombrotoxic poisoning generally results from eating fish from the families Scomberesocidae, Scombridae and Pomatomae, which include tuna, bonito, mackerel, and bluefish. Scombroid poisoning occurs when individuals eat fish that are partially decomposed, containing high levels of histamine as a result. Bacteria cause the breakdown of the tissue histidine into histamine and saurine at temperatures above 37°C (99°F). The spoiled fish frequently has a peppery or sharp taste, which to some people is not unpleasant. Signs and symptoms of scombroid poisoning usually occur within the first hour. The symptoms include diarrhea, hot flushed skin surface, bright red rash (face and trunk), sweating, nausea, headache (can be severe), stomach pain, vomiting, mouth-throat burning sensation, fever, dizziness, tight chest, swollen face, and respiratory distress. Cooking does not destroy the toxic substance in the fish flesh. Cimetidine (Tagamet®) has proved more useful therapeutically than antihistamines for treatment. Always eat fresh fish that has been well refrigerated. If you catch or spear fish, keep them well refrigerated until you can eat or freeze them. The most dangerous of all food poisonings is without a doubt those produced by tetrodotoxin, which is a very potent material found in the flesh of pufferfish (figure 2-21), globefish, blowfish, or swellfish - what the Japanese refer to as fugu. Many people worldwide risk death by eating species from the Tetradontiadae family. Some describe this as playing “Russian Roulette” with chopsticks. Eating these fish often produces a strange warming sensation, or tingling, over the entire body. In high concentrations, the tetrodotoxin can cause death in a few minutes by blocking the sodium channels of muscles and nerves. In other words, this is a potent neurotoxin that stops nerve functions, stops breathing, and causes death. The toxicity varies from species to species and from organ to organ. The liver and gonads are usually the most toxic parts of puffer fish. Puffer fish raised in aquaculture (an artificial environment) do not produce tetrodotoxin. In their natural environment, pufferfish feed on algae that are covered with a bacteria of the genus Alteromonas, which we now know produces tetrodotoxin. The northern puffer Spheroides maculatus, which is caught along the east coast of the United States, is consumed in large quantities during some years and appears safe to eat. This is probably because the levels of toxin are so low in their tissues. The symptoms of “fugu” or tetrodotoxin poisoning include: weakness, dizziness, pallor, tingling around the mouth, lips, tongue and throat, increased salivation, low blood pressure (hypotension), vomiting (severe and frequent), cyanosis, slow heart beat (bradycardia), difficulty breathing (dyspnea), and is followed by shock symptoms. The onset of symptoms is rapid - from 5 to 45 minutes - and death may occur suddenly without warning. Treatment includes CPR, oxygen, intravenous fluids, atropine, and saline stomach washes. Avoid eating box-
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