CIGUATERA


	Under Sea Adventurers Dive Club

CIGUATERA or Ichthyosarcotoxin

Ray McAllister

Ciguatera is a form of fish flesh poisoning, which is exactly what ichthyosarcotoxin means! It is grossly under reported in tropical areas of the world where it is often listed as "sick to one's stomach" or "gut flu", etc. Only in the really severe cases is it likely to be recognized as a potentially dangerous form of poisoning caused by eating the flesh of a variety of tropical fish, but particularly of barracuda.

The poison is apparently produced by a variety of tiny marine organisms, dinoflagellates, which typically grow on various marine algae. These include sargassum weed, sea lettuce, Dictyota, Caulerpa, spaghetti grass, peacock algae, etc. Here the dinoflagellates thrive under warm waters, particularly in summer and fall, and produce in their tissues a poison called ciguatoxin. The algae are often preferred foods for a variety of herbivorous fish which eat, not only the algae, but the associated dinoflagellates and their toxin. The fish appear not to be affected by the toxin, although how one would tell a nauseated or diarrheic fish, I'm not sure. It accumulates in the fatty tissues of the fish and remains there until a reef predator eats the herbivore and then it concentrates in the predator's fatty tissues. For predator you should read "barracuda, grouper, amberjack, snapper, etc." If the predator eats enough herbivores who have, in turn, eaten enough algae with attached dinoflagellates, a toxic dose of ciguatoxin is available for the members of the next trophic level (the critters-mostly man-that eat the predators!)

Now along comes a recreational or commercial fisherman and the predator ends up on someone's table. Again, depending upon the parts of the fish eaten and the amount eaten, ciguatera may manifest itself in a variety of ways.

While eating the same fish at the same table, a few folks will not be affected at all. A further few will report stomach problems and pass it off as "bad fish", while the unlucky ones will have severe stomach distress, and a variety of neurological symptoms such as aching joints, metallic or peppery taste, dryness in the mouth and throat, skin itches, dizziness and nausea and, very diagnostic, reversal of hot and cold sensation. It is reported that an ice cube touched to the tongue feels hot. Few will test a hot poker touched to the tongue, but I suppose it would feel cold. Apparently a few deaths have been reported by Dr. Jack Randall, mostly from eating significant amounts of large barracuda.

In Bermuda, there was a Warrant Officer at Kindley Air Force Base who liked to fish. He brought home a large barracuda one day and the family had this fine eating fish for supper. Then the symptoms started. Most of those listed above were present in the next few days. However, the symptoms persisted for weeks and eventually he and his family were sent back to the States on a medical transfer. I am told that 2 years later he still got dizzy when he stood up at his desk. This points up one of the other serious aspects of ciguatera. It apparently dissolves in fatty tissue in your body and is released over time as you metabolize this tissue, and the symptoms can persist for weeks to years. Yet some people seem not to be significantly affected.

There are no easy ways to tell if a particular fish is ciguatoxic. Many "old wives tales" exist but none are any good. DeSylva and Poli list a series of these tales and tell you THEY DO NOT WORK!

Silver does not discolor on contact with a ciguatoxic fish.
Flies are supposed to avoid landing on and eating toxic fish.
Ants wont feed on toxic fish.
Such a fish is "sick" and will not fight well when hooked.
Teeth of a toxic barracuda are dark in color and a safe barracuda has white teeth.

ALL FALSE!

I believe that the best way to tell is to fillet your fish, mark the packages with a death's head and feed the carcass to the neighbor's (dare I say it) cat! Watch the cat eat it! In a moment I'll tell you why this is important! If the cat eats a reasonable portion and is still OK the next day, scratch out the skull and eat the fish. While not foolproof, this appears to be an acceptable procedure for all but the neighbor and the neighbor's cat!

Recently a test for ciguatoxin in fish was reported. I understand it costs about $5.00 per fish, but with fish selling for $5/lb, ten lbs of fillets would be worth the price. The other preventative measure to insure that you don't get ciguatera is to eat only small marine carnivores. Many people say to eat fish weighing less that 10 lbs. Many years ago, one of the experts in the investigation of ciguatera (Mark Poli) told me on the telephone that he preferred 5 lbs and under. Yet even that is not totally dependable for Dr. Don DeSylva, of Miami's Rosensteil School of Marine and Atmospheric Sciences, reported several 4 lb barracuda which poisoned the consumers. Do not buy large, thick fillets which probably came from a large fish. Small snapper, grunts, etc are common and very tasty. Eat them.

The Atlantic Ocean occurrances are especially concentrated where medical services report possible poisoning, where large populations are concentrated and where folks eat a lot of fish. This means Florida, the Bahamas and Caribbean nations. Most of the English language literature naturally lists Florida and Bahamas occurrances.

Some authorities recommend injections of mannitol as soon as possible after symptoms occur. For more information on this I refer you to Dr. Donald De Sylva, Prof. of Marine Science, Rosensteil School, 4800 Rickenbacker Causeway, Miami 33149 (305) 350-7334.

There is another type of poisoning, called scombroid poisoning, which occurs if one eats a scombroid fish, particularly the mackerals and tunas, after they have been left in the sun and not iced. Some chemical in the outer flesh changes as the fish dries out and causes, in humans, very rapid pulse rates and severe reddening of the skin. It is very scary and couse conceivably cause death in a weak person. It is very different in symptoms and cause from ciguatera.

Now two anecdotes about ciguatera incidents (or non-incidents as the case may be.) While in Micronesia during Operation Stellaroid Control, looking for evidance of the Crown of Thorns Starfish depradations on the coral reefs of Truk, the Trukese native assisting us caught a doctorfish or tang on hook and line. He started to fillet it and give us all pieces as sashimi (raw fish). Dr. Bob Jones knocked it out of his hands telling him "Don't eat that. It is probably ciguatoxic." Tawn Paul, the native, said "no problem here, we eat these all the time!" Bob had just done his doctoral dissertation at the University of Hawaii on the association between the doctorfish of the same species and ciguatera. We tentatively ate a little raw doctorfish and had no ill effects but Dr. Jones would not touch it!

The last story is perhaps amusing now, but it was not at the time it happened. The Kindley Air Force Base Fishing Club held a large tournament offshore Bermuda and afterwards all met at one of the officer's house for a fish cookout. Late that night the last guest left and the lady of the house told her husband that she could not face all these fishy dishes in the morning so they set about cleaning up and putting dishes thru several fillings of the dishwasher. Early in the process she found a plate of uneaten barracuda and told her husband she'd put it out for the cat. She called the cat and left it eating the barracuda. When, much later, she went out to get the last plate, she found the dead cat next to the plate and she panicked. She called Colonel Frese, Kindley's head of the KAFB Hospital, who had been at the banquet, told him about the cat and asked what to do? Colonel Frese told her to organize a telephone network and get everyone who had been at the party to the hospital to have their stomachs pumped!

In the very wee hours of the morning, as she and her husband came back from the hospital, the neighbor's wife came over and told her "Honey, I did not want to spoil your party last night, but at 2AM when I drove my husband to the Base to fly a WB-50, I ran over your cat. Rather than spoil your evening I laid her at the door and figured to tell you this morning." The fish wife grabbed her by the throat and told her that, on the pain of sudden death, mention this to no one on the base. She said "Because of your kindness we pumped the stomachs of 40 couples and there are 80 unhappy officers and their wives who would get violent if they knew." I was told the story as the wife in question was leaving for the States and I think this is the first time a very good story has leaked out. So watch the cat eat the fish and keep track of it afterward so it doesn't get hit by a car!

By the way, I acknowledge the assistance now and in the past, of Dr. De Sylva, Dr. Mark Poli and Dr. Dan Baden, all of the Rosensteil School, who have given me papers, telephone interviews, etc.