Ciguatera Fish Poisoning - Causes, Symptoms, Risk, Treatment and Prevention

What Is Ciguatera Fish Poisoning?

Ciguatera fish poisoning occurs due to the ingestion of ciguatoxins (CTX) and maitotoxins (MTX), and it is considered to be a food poisoning or food-borne illness. It is also known as ciguatera, and it is caused by eating fish contaminated with the ciguatera toxin. These ciguatera toxins and maitotoxins are heat-stable lipid-soluble compounds produced by the microscopic sea plants known as dinoflagellates. Dinoflagellates are single-celled marine organisms that cause symptoms by interfering with sodium and calcium channels on the cell membrane, disrupting the signals between the nerves and muscles. The ciguatera toxins may be found concentrated in:

1. Tropical reef fish and the most common ones are,

• Grouper.

• Red snapper.

• Barracuda.

• Amberjack.

• Eel.

• Spanish mackerel.

• Sea bass.

2. Inshore habitat fish species.

Where Is the Risk of Ciguatera Fish Poisoning Greatest?

Ciguatera fish poisoning is more common in tropical and subtropical reef waters. Ciguatera toxin mainly accumulates in large predator fishes of more than two kilograms or about 4.5 lbs, such as red snapper and other predatory reef fish. This is because these giant fishes eat other smaller fishes that consume toxin-producing algae, which live in coral reef waters. The toxin-producing causative organisms that are fed by the above-mentioned fishes are:

• Dinoflagellates (benthic dinoflagellates).

• Algae.

• Gambierdiscus toxicus.

• Prorocentrum spp.

• Ostreopsis spp.

• Coolia monotis.

• Candinium spp.

• Amphidinium carterae.

When the fish from the ciguatera endemic areas are being shipped worldwide, poisoning is potentially more common in any area. The greatest threats are posed in the,

• Caribbean sea.

• West Indies.

• Hawaii.

• Pacific ocean.

• Indian ocean.

• Texas.

• California.

• Guam.

• The virgin islands.

• Coastal Central America.

What Are the Causes of Ciguatera Fish Poisoning?

It occurs due to the intake of ciguatera toxin. Ciguatera toxin is a tasteless, odorless substance that cannot be destroyed in cooking. This toxin is harmless to fish but is poisonous to humans. The only way humans get exposed to this toxin is by eating the ciguatera-contaminated tropical or subtropical fish. It causes symptoms in the gastrointestinal, cardiac, and nerve tissues in humans and other mammals due to the activation of voltage-dependent sodium channels by the toxins. It is said that around 25,000 cases are reported every six months worldwide, but it rarely causes death. However, children are exposed to more severe symptoms.

What Are the Symptoms of Ciguatera Fish Poisoning?

Onset - The ciguatera fish poisoning symptoms generally begin after five to seven hours of eating the fish contaminated with the ciguatera toxin. However, it can occur as early as two hours after ingestion or may take one full day to show up.

Symptoms - After the intake of ciguatera toxin-contaminated fish, it may result in the following symptoms.

Cardiovascular Symptoms:

• Tachycardia.

• Bradycardia.

• Reduced blood pressure.

• Arrhythmia.

Gastrointestinal Symptoms:

• Nausea.

• Vomiting.

• Diarrhea.

• Abdominal pain.

• Muscle pain.

Neurological Symptoms:

• Numbness.

• Tingling.

• Dizziness.

• Vertigo.

Severe Symptoms:

In severe cases of ciguatera fish poisoning, the following symptoms can occur.

• Shortness of breath.

• Tearing.

• Salivation.

• Chills.

• Paralysis.

• Rashes.

• Anaphylaxis.

• Hypotension.

• Bradycardia.

• Coma.

Only less than 0.5 % of people die due to ciguatera fish poisoning.

The classic finding of ciguatera fish poisoning is the reversal of hot and cold sensation. It is a burning sensation when it comes in contact with the cold (allodynia). Inside the oral cavity, it may show the loosening of the teeth, and also, there might be a generalized itching that becomes intense after some time.

Why Is Ciguatera Fish Poisoning Considered a Risk to Travelers?

Ciguatera toxin is caused by eating parrotfish, barracuda, grouper, moray eel, amberjack, etc., or by eating fish that are highly involved in the food chain. As the fishes are being transported worldwide, ciguatera may occur anywhere, but the risk is higher in the fishes that come from the pacific ocean, Indian oceans, and the Caribbean sea. It has been reported that 30 of every 1000 people who travel to these areas get ciguatera fish poisioning. In addition, the western Gulf of Mexico and the eastern Mediterranean are also at great risk for ciguatera fish poisioning.

How Can Ciguatera Toxin Be Detected?

Some tests have reported the ability to detect this toxin in food, but there is no officially sanctioned test available to detect ciguatera toxin. There is ongoing research about detecting ciguatera toxin, and the investigators are researching if there is any possibility of using monoclonal antibodies to both detect the toxin and also using these antibodies to treat patients.

How Long Does Ciguatera Fish Poisoning Last?

The duration of time that someone suffers from the effects of ciguatera fish poisoning can differ from person to person and is directly related to the intensity of their symptoms. In most instances, the symptoms of ciguatera fish poisoning can last for days to weeks, but in certain circumstances, they can continue to manifest themselves for months or even years.

How Is Ciguatera Fish Poisoning Treated?

It is said that there is no specific treatment or antitoxin for ciguatera toxin.

Vomiting - When ciguatera toxin-containing fish is ingested within the last four hours, voluntarily induce vomiting if the person is awake and alert.

Ipecac - This medication was suggested before as it contains a substance that induces vomiting, but physicians think that it resulted in too much dehydration. Therefore, currently, activated charcoal is being prescribed.

Activated Charcoal - Physicians recommend activated charcoal to decontaminate the gastrointestinal tract. It absorbs the toxin if it is done within three to four hours of toxin intake.

Maintain Hydration - As we are expelling out the contents present within the stomach, intravenous fluids are necessary to maintain hydration, especially when there is uncontrollable nausea and vomiting.

Pharmacological Treatment - Osmotic diuretics such as Mannitol (Osmitrol) are given to reduce the symptoms. In order to reduce the neural pain symptoms, Gabapentin (Gralise, Horizant, Neurontin) and Amitriptyline (Endep, Elavil) are given. For overcoming intense itching, Hydroxyzine (Vistaril, Atarax) and Diphenhydramine (Benadryl) may be prescribed. Acetaminophen (Tylenol) and other non-steroidal anti-inflammatory drugs help reduce pain.

Aside from that, it is important to drink enough water and stay away from stimulants like alcohol, caffeine, and other similar substances.

How Can Ciguatera Fish Poisoning Be Prevented?

Currently, there is no medicine or vaccination that can be used to prevent ciguatera poisoning. However, some precautions can help, which are listed below.

• Limit the intake of reef fish and also the above-mentioned fishes.

• The most important thing to avoid is eating moray eel and barracuda because they are more likely to cause ciguatera fish poisoning.

• Avoid eating the intestines, eggs, liver, or head of the fish as they may have an increased concentration of toxins.

• The ciguatera toxin does not show any change in the fish, such as affecting the appearance, smell of fish, or taste. Thus, we will not come to know that the fish is contaminated.

• Even though the fish is thoroughly cooked, it yields the same concentration of toxin because ciguatera toxin is highly dangerous, and it does not get destroyed by heat.

• People who have been exposed to ciguatera toxin should avoid the intake of alcohol, nuts, fish, nut oils as it may trigger recurrent symptoms.

Note: It is important for a person to seek medical attention if they suspect they have ciguatera fish poisoning, particularly if the symptoms are severe or if they have preexisting health conditions that could be made worse by the poisoning.

Conclusion:

Ciguatera fish poisoning is a serious condition and may rarely lead to death. So, immediate medical attention is needed in all cases as symptoms may progress rapidly. In severe cases, hospitalization with intravenous fluids might be required. When necessary, a toxicologist (doctor specialized in poisonings) can be consulted.