Ciguatoxine

Ciguatoxins are a family of highly potent marine neurotoxins produced by dinoflagellates of the genus Gambierdiscus and related taxa. These lipophilic polyether compounds accumulate in reef fish through the marine food web, and human exposure occurs when contaminated fish are consumed. Ciguatoxins are heat-stable and resistant to cooking and freezing, so preparation does not reliably eliminate the risk.

They act by binding to voltage-gated sodium channels in cell membranes, keeping them in an activated state. This prolongs membrane depolarization and disrupts nerve and cardiac function, leading to a range of neurological and cardiovascular symptoms. The toxins comprise multiple congeners, including Pacific ciguatoxin-1 and various Caribbean forms, with differing potencies.

Ciguatoxins originate in tropical and subtropical reef zones where Gambierdiscus dinoflagellates proliferate on macroalgae. Through the food chain, these toxins accumulate in herbivorous fish and become increasingly concentrated in larger predatory reef fish. Global warming and changing ocean conditions are expanding the geographic range and frequency of outbreaks.

Ciguatera fish poisoning presents with rapid-onset gastrointestinal symptoms (nausea, vomiting, diarrhea) followed by neurological symptoms such as paresthesias, altered temperature perception, dizziness, and fatigue; some patients experience cardiovascular changes. Onset is typically within hours to days after ingestion. Diagnosis is clinical, based on exposure history; laboratory confirmation by LC-MS exists but is not routinely available.

There is no antidote. Management is supportive, including hydration and symptom control; some reports describe benefit from intravenous mannitol if given early, but evidence is inconclusive. Prevention emphasizes avoiding high-risk reef fish species and sizes, and issuing public health advisories in affected regions. Cooking and freezing do not reliably destroy the toxins.