NAUI Master Scuba Diver 52 The Diving Environment “Ichthyosarcotoxism” is a term used for a type of poisoning identified with eating a fish contaminated with a specific poison type. Venomous animals are those creatures capable of producing a toxin in a highly developed secretory gland (venom sac) or group of cells and delivering this material (toxin) through a sting or bite. These are the animals that have fangs, claws, stingers, spines, or some other mechanism for delivering a toxin. Unlike the oral toxins, venoms are usually large molecules that are detoxified by heat or gastric juices. Toxins delivered by a venom apparatus are often called parenteral toxins. Oral Toxins Divers often gather things from the sea to eat, either by spearfishing, crabbing, or picking up shellfish. Paralytic shellfish poisoning (PSP) is caused by chemical agents known as saxitoxin and neosaxitoxin. These agents are synthesized in microscopic plants known as fire algae (Pyrrophyta), specifically dinoflagellates (Gonyaulax tamarensis or Gymnodinium breve) commonly found in the marine plankton. These toxic dinoflagellates occasionally increase their numbers tremendously, causing what has become known as a “red tide.” Shellfish such as clams, oysters, and mussels are filter feeders, ingesting large numbers of dinoflagellates and concentrating their toxins in the shellfish tissues. If you collect and eat the contaminated shellfish, you could be poisoned. This is a seasonal toxin and only occurs when there has been a dinoflagellate “bloom” or red tide, usually between May and October in the northern hemisphere, hence the time-old admonition not to eat oysters in months without an “R.” Paralytic shellfish poisons (saxitoxins) are neurotoxins which means they can cause you to stop breathing (respiratory arrest). The effective treatment is to keep the victim breathing for 24 hours following onset while the toxin is slowly destroyed in the body. Cardiopulmonary resuscitation (CPR) may be life-saving for the individual who has been exposed to a large dose of this phytotoxin. Getting the victim to a hospital respirator is essential. Fish are a high protein, low fat source of food for FIGURE 2-21. PUFFERFISH anyone following the American Heart Association guidelines for good nutrition. Most contain little or no cholesterol, and those present are primarily of the “good type.” There is increasing consumption of fish and shellfish world wide. Some of the more popular fish are becoming difficult to catch, and the supply is dwindling, so we find ourselves eating new species. Fortunately, we are simultaneously becoming more sophisticated in our tastes, but in some cases, the demand for seafood is outgrowing our scientific information about specific species. Fish can be rapidly transported by air to areas of the world where people never ate the species before. Along with this improved transport system, we are finding outbreaks of fish poisonings far from the sea, often to the surprise of the local health officials. Technologic improvements have also helped increase the harvesting of traditional seafoods and new species. All of these factors have contributed to a rise in the occurrence of illness resulting from fish toxins (ichthyosarcotoxism). Ciguatera fish poisoning is probably the most common ichthyosarcotoxism found world wide. It is a disease with both neurologic and gastrointestinal symptoms. Various reef dwelling fishes may transmit the poison or group of toxins known as ciguatoxin. Again, a dinofla-
20047TC
To see the actual publication please follow the link above