How Do I Know If My Fish Is Contaminated by Ciguatera Toxin?

Ciguatera fish poisoning is caused by the consumption of reef fish that contain accumulated ciguatoxins. These toxins are produced by dinoflagellates, which are small marine organisms (microalgae) that belong to the species Gambierdiscus toxicus. Typically, they live in the coral reefs in tropical or subtropical areas.

Small herbivorous fish feed on these dinoflagellates. The ciguatoxins bio-accumulate in the marine food chain and contaminate larger predatory fish, usually weighing over 6 lbs. When humans consume the contaminated fish, it causes ciguatera fish poisoning.

Fish at risk of ciguatera food poisoning

More than 400 different species of fish have been associated as the cause of ciguatera fish poisoning and such fish are said to be ciguatoxic fish. Ciguatera toxin may be found in any large reef fish but is mostly found in barracuda, grouper, red snapper, moray eel amberjack, perch Spanish mackerel, parrotfish, hogfish, sturgeon fish, kingfish, coral trout and sea bass.

Symptoms of ciguatera food poisoning generally begin six to eight hours after eating the contaminated fish, and may include:

• Gastrointestinal symptoms: Characterize the first stage of ciguatera poisoning and appear within 12 hours of consuming the contaminated fish, lasting for a couple of days.
  • Abdominal cramps and pain
  • Nausea
  • Vomiting
  • Diarrhea
• Neurological symptoms: The next set of symptoms affects the neurological system. These symptoms can appear in a few hours or several days after consumption of the contaminated fish and may continue for several months.
  • Mental confusion
  • Poor coordination or lack of balance
  • Muscle pains
  • Joint pain
  • Pain in the teeth (may feel loose)
  • Headaches
  • Hallucinations
  • Dizziness
  • Vertigo
  • Tingling sensation
  • Numbness of the lips, tongue, hands and feet
  • Hot and cold sensation reversal
• Cardiovascular symptoms: The third set of symptoms affects the cardiovascular system.
  • Orthostatic hypotension
  • Bradycardia
• Cold allodynia: A characteristic symptom of ciguatera food poisoning is cold allodynia, which is a dysesthesia (unpleasant, abnormal sensation) that induces a burning sensation when in contact with cold objects.

Severe cases of ciguatera poisoning may result in breathing difficulties, muscular paralysis, coma, itching, skin rash, stiff neck, sweating, chills, tearing of the eyes or drooling.

Death due to heart or respiratory failure may occur in rare cases within 24 hours.

Immediate medical attention is necessary for ciguatera food poisoning since the symptoms can rapidly progress in certain patients, and may include gastric lavage in severe cases.

There is no specific antidote for ciguatera poisoning. However, the mainstay of treatment is supportive care, such as:

• Intravenous administration of fluids: To maintain hydration.
• Diphenhydramine and hydroxyzine: To help relieve itching.
• Amitriptyline and gabapentin: To help reduce neural pain symptoms.
• Non-steroidal anti-inflammatory drugs and acetaminophen: To help reduce pain.
• Verapamil (Calcium channel blockers): To treat some of the symptoms that occur after the initial digestive stage symptoms.
• Vitamin supplements and steroids: To support recovery.

Consumption of alcohol, fish, nuts and nut oils should be avoided after ciguatera poisoning because these may cause recurrent symptoms.

Prevention of ciguatera fish poisoning

Ciguatera food poisoning may be prevented by:

• Avoiding eating reef fish that weighs 6 lbs or more.
• Avoiding eating the liver, intestine, head and roe of smaller reef fish.