Ciguatera Poisoning

Ciguatera poisoning occurs after eating reef dwelling fish that have fed on toxic plankton. Symptoms include diarrhea and neurological signs

This can occur sporadically in the Pacific and Caribbean. 

This toxic plankton proliferates in dead and dying coral reefs and is becoming more common. This is especially noted in Pacific islands where nuclear radiation has damaged the coral atolls increasing the incidence of ciguatera.

Affected fish cannot be distinguished by inspection, smell or taste, and cooking does not neutralize the toxin. Commercial tests to screen for Ciguatera are being developed.

I recently met a Cook islander who explained while eating the same plate of fish his wife became very ill while he did not as individual effects are variable. Evidence points that past nuclear testing in French Polynesia was now influencing the ciguatera levels on his island.

The best way to avoid during outbreaks is to avoid eating large predatory - type reef dwelling fish that are more likely to bio-accumulate the toxin. The toxin is more concentrated in the head, liver, and gut of these fish. Examples of some commonly affected species include: red snapper, grouper, barracuda, coral trout, cod and amberjack.

Symptoms usually occur after 1-6 hours (but have been up to 30 hours) after eating. Most people are mildly affected with gastrointestinal symptoms (diarrhea, vomiting, and abdominal pain) but neurological symptoms can also occur (muscle aches, weakness, blurry vision and burning). Ciguatera poisoning also has particularly bizarre symptom in that some will report a reversal of hot and cold sensations. Symptoms usually last less than 2 weeks.

Cruise passengers should consume fish that is acquired through either the Cruise ship restaurant or local well-established shore restaurants that work with local licensed fishermen. In the event of suspected food poisoning, report to the infirmary as this can aid you immediately and help the ship’s doctor and cook determine if a food bourne illness is present and prevent others from being sick.

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Ciguatera poisoning has resulted in some neurological problems persisting for weeks, and in rare cases, even years. Symptoms have sometimes returned after eating contaminated fish a second time. Several years ago there was a case of imported swordfish into Canada that was responsible for several poisonings.

Diagnosis is based on history. Treatments involve Antihistamines and sometimes administering Mannitol (a medication that may be useful as a partial antidote).

Mannitol is a drug used for decreasing head injury and was first used in 2 ciguatera victims who were believed to also had head injuries and improved their neurological symptoms. Although not a routine treatment is show some promise for possible use in reversing the bizarre neurological effects of the ciguatera toxin.

Often many local island fishermen have used their knowledge of tidal patterns, locations to fish and species not to fish to choose fish that do not have ciguatera.