Ciguatoxins and Ciguatera

Ciguatoxin is a large, heat stable, polyether toxin (Figure 1) produced by certain strains of Gambierdiscus toxicus found in tropical and subtropical waters around the world. Following blooms of the dinoflagellate, the toxin can accumulate up the food chain into large, predatory fish, some of which are eaten by humans. Species involved in Queensland include grouper, coral trout, narrow-barred Spanish mackerel, and Maori wrasse.

FIGURE 1

Ciguatoxin type 1 backbone

Ciguatoxin type 2 backbone

Ciguatera poisoning

Ciguatoxin is the toxin responsible for the poisoning syndrome known as ciguatera, which is characterised by numbness and tingling around the mouth, hands, and feet; joint and muscle pains with weakness or cramps; vomiting, diarrhoea, chills, itching, headache, sweating, and dizziness; and reversal of temperature sensation, where cold things feel hot and hot things feel cold. These symptoms all appear to arise because of ciguatoxin's ability to activate the sodium channels found in nerves and muscles.

Ciguatera usually begins several hours after eating ciguatoxin tainted fish and individuals are thought to become sensitised to the toxin, with the symptoms becoming more severe with repeated exposure. Ciguatera may continue for a week or more in mild cases, and up to several months or more in some more severely affected victims. The simplest thing to do for a victim is to provide symptomatic relief, although intravenous mannitol can be effective at relieving the symptoms in more severe cases. It is best that a person suffering from ciguatera avoid eating fish, fish products, and alcohol for up to 6 months, as these may cause a recurrence of symptoms. A small percentage of sufferers develop allergy-like reactions to a range of foods including, peanuts, chicken and pork. There is as yet no validated test available for the reliable detection of ciguateric fish.

Further reading

Ciguatera poisoning by Professor Hokama, University of Hawaii 

Ciguatera management by Dr. Richard Lewis, University of Queensland 

Lewis RJ (2001) The changing face of ciguatera. Toxicon 39, 97-106.

Lehane L (2000) Ciguatera update. Med J Aust. 172, 176-179.

Dechraoui MY, Naar J, Pauillac S, Legrand AM (1999) Ciguatoxins and brevetoxins, neurotoxic polyether compounds active on sodium channels. Toxicon 37, 125-143.

Fenner PJ, Lewis RJ, Williamson JA, Williams ML.A (1997) Queensland family with ciguatera after eating coral trout. Med J Aust. 166, 473-475.

Tosteson TR (1995) The diversity and origins of toxins in ciguatera fish poisoning. P R Health Sci J. 14, 117-129

Glaziou P, Legrand AM (1994) The epidemiology of ciguatera fish poisoning. Toxicon. 32, 863-873.

Lewis RJ, Holmes MJ. (1993) Origin and transfer of toxins involved in ciguatera. Comp Biochem Physiol C. 106, 615-628.

Scheuer PJ, Takahashi W, Tsutsumi J, Yoshida T (1967) Ciguatoxin: isolation and chemical nature. Science 155, 1267-1268.

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Page last updated - December 18, 2008

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