Ciguatera in Hawaii

Above is a map of fish ciguatera levels found in fish caught on the Big Island (courtesy Dr. Paul Bienfang of the oceanography department at the University of Hawaii in Honolului).  Although never seen at the high levels seen in the Caribbean such as South Florida, it's still a risk of seafood consumption here.

Ciguatera is a gastrointestinal, cardiovascular, and neurological illness which is caused by the eating of fish which have eaten other fish which have eaten a tiny free-swimming organism, the protozoan dinoflagellate called Gambierdiscus toxicus.

Gambierdiscus makes a toxin (ciguatoxin) which is not metabolized by fish, so that it is concentrated along its path in the food web.  Thus, eating large carnivorous fish such as large moray eels or barracuda are more likely to cause the illness. Unfortunately, unlike the more common bacterial food poisoning toxins, ciguatoxin is not broken down by cooking. The toxin causes increased permeability of the resting axon sodium channel, increasing depolarization and thus directly activating sensory and other peripheral and indirectly central nerve circuitry (though the toxin is excluded from the brain itself, since it does not cross the blood-brain barrier).

Symptoms of ciguatoxin poisoning include nausea and vomiting and diarrhea, symptoms typical of other types of food poisoning and gastroenteritis.  Unlike those conditions, the GI problems are accompanied or followed by numbness and tingling in face and extremities, often around the lips or mouth. A pathonogmonic complaint is reversal of hot and cold, so that hot objects feel cold and vice versa. Cardiovascular symptoms are due to autonomic dysfunction with bradycardia and hypotension which may cause syncope. Fatigue is common but actual weakness or paralysis is rare, unlike botulism.

Since ciguatoxin is stored in the fat depot of the body and not broken down, previous bouts of the poisoning may actually make future bouts more likely and lead to chronic nervous system symptoms in those with ongoing exposure. Fortunately, recovery is the rule once further toxin exposure is removed.

According to the University of Hawaii, ciguatera increases in times of higher water temperature in the late summer.  That's the next 3 to 4 months here.