Ciguatera Fish Poisoning (Toxin) Definition
- 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).
Ciguatera Fish Poisoning (Toxin) Symptoms
Eating ciguatera toxin contaminated fish result in the following symptoms:
- Symptoms generally begin 6 to 8 hours after eating the contaminated fish but can occur as early as 2 or as late as 24 hours after ingestion.
- Symptoms include nausea, vomiting, diarrhea, muscle pain, numbness, tingling, abdominal pain, dizziness, and vertigo. The classic finding of hot and cold sensation reversal is actually a burning sensation on contact with cold (allodynia).
- Teeth may feel loose and itching may be intense.
- Severe cases of ciguatera poisoning may result in shortness of breath, salivation, tearing, chills, rashes, itching, and paralysis. Bradycardia, coma and hypotension can occur. Death due to poisoning is rare (less then 0.5 %).
Ciguatera Fish Poisoning (Toxin) Treatment
There is no specific antitoxin available for ciguatera toxin.
- Some investigators have suggested vomiting should be induced if the victim is awake and alert and has eaten ciguatera toxin-containing fish within the last 3 to 4 hours. Ipecac, a substance that causes vomiting, was suggested as the medication to use, but many investigators now think ipecac causes too much dehydration. Currently some physicians recommend gastrointestinal decontamination with activated charcoal. Activated charcoal may absorb the toxin if done 3 to 4 hours after ingestion.
- Maintain hydration. Intravenous fluids may be necessary for uncontrollable nausea and vomiting.
- No specific antidote is available.
- Osmotic diuretics have been used to decrease symptoms (for example, mannitol [Osmitrol]).
- Amitriptyline (Elavil, Endep) and gabapentin (Neurontin, Gralise, Horizant) may help reduce neural pain symptoms
- Diphenhydramine (Benadryl) and hydroxyzine (Atarax, Vistaril) may help relieve itching.
- NSAID's and acetaminophen (Tylenol and others) may reduce pain
- Avoid alcohol, fish, nuts, and nut oils after exposure to ciguatera toxin because they may trigger recurrent symptoms.
When to Seek Medical Care for Ciguatera Toxin Poisoning
- Severe cases require hospitalization for intravenous fluids.
- Immediate medical attention is necessary for all cases because the symptoms may rapidly progress in a few patients.
- A doctor should be consulted about treatment with available medications. If necessary a doctor specializing in poisonings (toxicologist) can be consulted.
Ciguatera Toxin Detection
Although some tests report the ability to detect this toxin in food, there are no officially sanctioned tests for ciguatera toxin available. Research is ongoing; investigators are researching the possibility of using monoclonal antibodies to both detect the toxin and to use the antibodies to treat patients.