Ciguatera

[Owly055]

Anybody who sails in tropical regions and catches and eats reef fish needs to be concerned about this neurotoxin produced by dinoflagellates living in reefs in many places, and consumed by reef fish, concentrated up the food chain.   

I would assume everybody already knows all about ciguatera, but here's one of many articles you should read if you are not familiar with it.

There is no antidote, no effective treatment, no cure for it's effects.  It's a poisoning, not a disease, and the neurological effects can last for many years.  There is a test kit, which is expensive, and often shows ambiguous results to the point that few people use it.   

Ciguatera poisoning is not rare at all.  The best prevention is to stick to deep sea type fish and avoid reef fish.

The best protection seems to be to take a cat with you.... if the cat shows signs of poisoning within a few hours of eating the fist......... don't eat it.   I would be happier using rats however.  They are more compact and they are "easy keepers", though I wonder how the customs folks would react when they heard you had a bunch of white lab rats on board ;-)

                                                   H.W.

[maxiSwede]

Having pet rats on board would probably be an interesting experience clearing in....


First time we ever encountered ciguatera was here in FrPol. In the Gambiers, where we spent 14 months, living on fish if not entirely so at least regularly, like 2-3 days a week.

There were, according to the local friends, only 3 species you could eat in the lagoon!  Never have I seen so many huge Arrot fish, Napoleons and more....

The most interesting thing was that one species, Ume Tare, was fine toe  at in one bay but not inthe next one a few hundred yards/meters away. A bit hard to grasp if you're inclined to scientifically and/ or logical explanations  8)

We never went against the locl advice, other cruisers did, and got sick. Some quite sick indeed.

Here in Tahiti, and the rest of the Societies, there are fewer species carrying the toxin, OTOH Tahiti is quite crowded relatively speaking, so we do not see much fish of enable size at all in the lagoon. Methinks the habit of fishing at night with strong lights and spearguns is detrimental to the sensitive ecosystem. pelagic fish are normally fine, though a friend of us told a story of an American cruiser who got sick by eating a big tuna caught at sea for several days in a row on passage. He got so bad he had to quit cruising and sold the boat - to the friend who passed on this story. Perhaps he had already built up toxin in his body earlier....

[Owly055]

     Unfortunately there is a lot of superstition regarding ciguatera.  That renders local advice possibly questionable in some places.  "If the flies land on it, it's OK".... If you get a tingling sensation when you touch it to your lips, throw it away, etc.    It would be nice to think that mahi mahi and tuna were "safe", but the truth is that they are high up on the food chain.  Of caught mid ocean, they are probably pretty safe............but how far have they traveled?   How cumulative is ciguatera?   Where is the toxin stored?   How can it be flushed from your system?    How individual is it?   I'm reminded of rattlesnake venom, and honeybee venom, almost identical.   Some people develop resistance, others develop sensitivity.  I know people who go into anaphylactic shock from a bee sting and will die if they don't get immediate treatment.  They are going to die from a rattlesnake bite.  On the other hand my girlfriend plucked 42 stingers out of me after I made a mistake capturing a swarm many years ago.   I had to cling to the tree as they stung me relentlessly, and climbed down and finished the job (wardrobe malfunction).   The only reaction was a touch of nausea for about 15 minutes.  A girlfriend of mine in the early 70's sat under a Juniper tree in the Deschutes canyon for 3 days after a snake bite, and then walked 3 miles to the cabin she was staying in, and drove herself to the hospital in Madras.  They gave her antibiotics to prevent infection.   Nothing more.  It might have killed the next person, but not Heather!  That was a girl with balls!!!
     The point is that it is probably highly individual as well as cumulative.

                                                                                   H.W.

Having pet rats on board would probably be an interesting experience clearing in....


First time we ever encountered ciguatera was here in FrPol. In the Gambiers, where we spent 14 months, living on fish if not entirely so at least regularly, like 2-3 days a week.

There were, according to the local friends, only 3 species you could eat in the lagoon!  Never have I seen so many huge Arrot fish, Napoleons and more....

The most interesting thing was that one species, Ume Tare, was fine toe  at in one bay but not inthe next one a few hundred yards/meters away. A bit hard to grasp if you're inclined to scientifically and/ or logical explanations  8)

We never went against the locl advice, other cruisers did, and got sick. Some quite sick indeed.

Here in Tahiti, and the rest of the Societies, there are fewer species carrying the toxin, OTOH Tahiti is quite crowded relatively speaking, so we do not see much fish of enable size at all in the lagoon. Methinks the habit of fishing at night with strong lights and spearguns is detrimental to the sensitive ecosystem. pelagic fish are normally fine, though a friend of us told a story of an American cruiser who got sick by eating a big tuna caught at sea for several days in a row on passage. He got so bad he had to quit cruising and sold the boat - to the friend who passed on this story. Perhaps he had already built up toxin in his body earlier....

[Owly055]

     There is a lot of active research on Ciguatera, but it seems to be confined to risk assessment and treatment.  As the ocean warms, the risks increase.  French Polynesia, The Caribbean, Florida, Hawaii, Guam, Fiji, Tonga, etc, are all seeing rapid increases in cases.   The only truly safe fish are pelagic fish like Mahi Mahi, Tuna, Dorado, etc, and fish from northern waters.  Those fish are all predator fish of course, and of course the ones that venture in to tropical waters could easily develop an accumulation of the toxin, as it builds up in the flesh, internal organs, and skin.   An organization called Ciguatera Online located in Papeete offers the advice at the bottom of the page, which is pretty universal.   
     Ciguatoxin is a basic hydrocarbon, and one would think that breaking it down in processing would not present an insuperable challenge........ Heat, time, and an inexpensive non toxic catalyst..........  A "pickling process" of some sort.   Obviously from what is written, heat alone will not break it down at normal cooking temps.  It seems to me that the right catalyst in a "marinade", followed by cooking to a suitable temp for a suitable time should allow a chemical breakdown or transformation, but of course if the breakdown product is toxic, or the catalyst is toxic, or expensive, or it requires 8 hours at 600F, it's a useless effort.   
      The populations of French Polynesia, Fiji, Tonga, Samoa, and other island nations such as the Caribbean  are heavily dependent of fishing, many of them like the people of the Taumotos and Kiribati have little else but coconuts, and a few fruit products, no land to speak of for raising livestock.  The populations of such places will become "unviable", and even more dependent on the outside world than they now are.   It also means that those of us who choose to travel to these places will be wedded to canned foods, and expensive imported foods, fruits, and a few locally produced meats...... if they are available at all.  Not a pretty picture!!

(after post edit):    I just ran across the information that Mahi Mahi, Dorado, & Tuna are not recognized as carriers.   Also that a product called Mannitol, which is a poorly digestable sugar often used in diabetic products, made by hyrogenation of sucrose over a nickel catalyst, is given IV to sufferers of ciguatera, as it breaks the toxin down.   This suggests the possible "marinade", which is widely found in nature.  Ironically it is most commonly extracted from seaweed in China at about 20% concentration, and the plane tree at about 90%, saw palmetto, etc (based on Wikipedia).   
     The "mannitol marinade" could possibly be a solution........but so far I've run across nothing suggesting such a thing.  Mannitol is alcohol soluble, and ciguatoxin is not water soluble.  I could see an alcohol infusion of plane or saw palmetto being a  marinade for fresh caught fish................  But who knows until someone tests it??  This is NOT the direction research is going.  It's common in Florida, Georgia, Mississippi, etc.... We've all probably seen it.   I would expect it to do well in French Polynesia or the Caribbean...... Pure speculation, but the solution may be right under our noses.

    Second addition:  Mannitol is available online quite cheaply.......... 500G (about a pound) for only about $12 as a bulk powder.

                                                 H.W.

A toxic fish cannot be distinguished from a nontoxic one, as toxins are tasteless, odorless and colorless. Als o, methods of preparation of the fish (raw, cooked, salted, dried ...) does not eliminate ciguatoxins from the fish tissue or make them less potent.     
However, it is possible to avoid and/or reduce the severity of poisoning by applying a few basic rules:

1- Seek advices from the town/island fishermen. They have, most of the time, very good knowledge of the areas and fish to avoid;

2- See our cartographysection, which report toxic areas as well as toxic fish or ask the local health authority in cha rge of your country's surveillance network;

3- Avoid eating the head and viscera, where toxins are mostly concentrated;

4- If any doubts, only eat a small amount of fish.

[Owly055]

In more reading I discovered that Mannitol is not used to break down the toxin, but to treat the neurological symptoms.  That said, it is amazing to me that with the increasing extent of this problem, and it is very widespread, and economically damaging as well as physically damaging, that there seems to be no body of research beyond treatment and avoidance of possibly toxic fish.   It's obviously a minor blip on the screen compared to heart disease and cancer, and other dramatic health issues, but it is very up close and personal to the people in the areas where it is a problem.  It simply is NOT a priority.  Logically it would seem that enzymes or catalysts and processing protocols should be able to be developed, but the focus is 100% on avoidance and treatment.  A  hemmoragic fever like Ebola, that effects a fairly small number of people (usually fatal), or Zika that  results in grotesque brain deformities is dramatic, and commands far more resources.  Few people die of ciguatera, but many are sickened, and entire industries brought down..... Try selling fish from Samoa in Hong Kong............  Like BSE and the cattle industry, this is no small matter......... but it isn't "dramatic".
                                                                                         H.W.