Ciguatera is a foodborn illness (food poisoning) caused by eating fish that is contaminated by ciguatera toxin. Ciguatera toxin is a heat-stable lipid soluble compound, produced by dinoflagellates and concentrated in fish organs, that can cause nausea, pain, cardiac, and neurological symptoms in humans when ingested.
The toxin may be found concentrated in large reef fish, most commonly barracuda, grouper, red snapper, eel, amberjack, sea bass, and Spanish mackerel.
These fish live in coral reef waters and accumulate the toxin when they eat smaller reef fish which feed on the dinoflagellates.
The area of concern include the Caribbean Sea, Hawaii, and coastal Central America.
With fish from ciguatera endemic areas being shipped nationwide, poisonings can potentially occur in any areas in the United States.
Ciguatera toxin tends to accumulate in large predator fish (weight over 2 Kg or about 4.5 lbs), such as the barracuda and other carnivorous reef fish, because they eat other fish that consume toxin-producing algae (dinoflagellates), which live in coral reef waters. The toxin has highest concentrations in fish visceral and sex organs.
Ciguatera toxin is harmless to fish, but poisonous to humans.
The toxin is odorless and tasteless, and cooking does not destroy the toxin.
Eating ciguatera-contaminated tropical or subtropical fish is the main way that humans are exposed to the toxin.
The toxin activates voltage-dependent sodium channels causing symptoms in human (and other mammals) gastrointestinal, cardiac, and nerve tissues.
There are about 50,000 reported poisonings worldwide per year, but rarely cause death; children have more severe symptoms (see below).