Which toxin is responsible for ciguatera poisoning?

• A. Scrombroid toxin
• B. Ergotamine
• C. Vibrio vulnificus toxin
• D. Ciguatoxin

Answer: (D)

Ciguatoxin is the toxin responsible for ciguatera poisoning. It’s produced by certain marine dinoflagellates in reef waters and accumulates in large predatory reef fish. The toxin is heat-stable, so cooking doesn’t destroy it, and people can be poisoned by eating contaminated fish such as barracuda, grouper, or snapper. Mechanistically, ciguatoxin binds to voltage-gated sodium channels and keeps them open, causing persistent depolarization of nerve cells. This produces the characteristic mix of neurological symptoms (tingling, numbness, dizziness, and a reversal of hot and cold sensations) and gastrointestinal symptoms (nausea, vomiting, diarrhea) that often begin within hours of ingestion and can last days to weeks. The other toxins listed cause different foodborne problems: scombroid toxin is a histamine-mediated reaction from spoiled fish; ergotamine is a fungal toxin causing vasoconstriction; Vibrio vulnificus toxin can cause severe wound infections or septicemia.