Ciguatera Fish Poisoning

This information is courtesy of Lora E. Fleming, NIEHS Marine and Freshwater Biomedical Sciences Center

The most commonly reported marine toxin disease in the world is Ciguatera, associated with consumption of contaminated reef fish such as barracuda, grouper, and snapper. Under-diagnosis and under-reporting (especially in endemic areas such as the Caribbean) make it difficult to know the true worldwide incidence of the Marine Toxin Diseases. At least 50,000 people per year who live in or visit tropical and subtropical areas suffer from Ciguatera worldwide. For example, CDC and others estimate that only 2-10% of Ciguatera cases are actually reported in the United States. In the US Virgin Islands, there are an estimated 300 cases per 10,000 or 3% of the population per year; a similar rate is found in the French West Indies. In St. Thomas, a household survey estimated that 4.4% of all households suffered from Ciguatera annually (at least 2640 persons per year or an annual incidence of 600 cases per year); in Puerto Rico, 7% of the residents have experienced at least one episode of Ciguatera in their lifetime.

Ciguatera, especially in the Caribbean, suffer for weeks to months with debilitating neurologic symptoms, including profound weakness, temperature sensation changes, pain, and numbness in the extremities. The dinoflagellate Gambierdiscus toxicus produces ciguatoxin throughout tropical regions of the world.

Clinical Presentation:

Ciguatera presents primarily as an acute neurologic disease manifested by a constellation of gastrointestinal (diarrhea, abdominal cramps and vomiting), neurologic (paresthesias, pain in the teeth, pain on urination, blurred vision, temperature reversal) and cardiovascular (arrhythmias, heart block) signs and symptoms within a few hours of contaminated fish ingestion. The pathneumonic symptom of Ciguatera intoxication is hot/cold temperature reversal, although not all patients report this.

The attack rate has been reported to be 73%-100% with ingestion of contaminated fish, without any apparent age-related susceptibility. Acute fatality, usually due to respiratory failure, circulatory collapse or arrhythmias, ranges from 0.1% to 12% of reported cases; presently in the Pacific, the mortality is less than 1%. Lethality is usually seen with ingestion of the most toxic parts of fish (ie. the liver, viscera, roe and other organs).

The clinical picture may be variable among individuals, even with the same food source, different ethnic groups, and possibly with different types of fish and/or geographic location. It appears that ciguatera from consumption of carnivore species may be more toxic than that from consumption of herbivores due to exposure to more than one toxin and/or transformation of the toxin(s) and/or an increased dose response. In Polynesia, Ciguatera is dominated and initiated by neurologic symptoms (90% of patients report paresthesias and dysesthesia), while reports from the Caribbean suggest that Ciguatera initially presents acutely as a gastroenteritis often with associated cardiovascular symptoms, with the gradual onset and dominance of neurologic symptoms over the first 24 hours. This may be due to different toxins mixtures elaborated by Caribbean and Polynesian G. toxicus.

The symptoms of Ciguatera poisoning, especially the paresthesias and weakness, can persist in varying severity for weeks to months after the acute illness. Prolonged itching due to chronic Ciguatera can present as a dermatologic disease when it is really due to ciguatera paresthesias. Chronic ciguatera can also present as a psychiatric disorder of general malaise, depression, headaches, muscular aches, and peculiar feelings in extremities for several weeks. It is reported that those with chronic symptoms seem to have recurrences of their symptoms with the ingestion of fish (regardless of type), ethanol, caffeine, and nuts 3 to 6 months from initial ingestion.

Ciguatera can be sexually transmitted. With exposure of the mother, premature labor and spontaneous abortion have been reported, as well as effects on the fetus and newborn child through placental and breast milk transmission.

In the differential diagnosis of Ciguatera, poisoning with the other marine toxins, especially NSP and PSP should be considered since dysesthesias with nausea, vomiting and diarrhea are the presenting symptoms. Obviously the history of fish versus shellfish consumption should help to differentiate. Type E botulism with ingestion of smoked fish, Scromboid and even Eosinophilic meningitis from helminthic infection of Angiostrongylus cantonensis from ingestion of raw mollusks, crabs and certain fish should be considered. Finally, poisoning with organophosphates pesticides can present initially with a similar clinical picture except for the exposure history.