Ciguatera fish poisoning — DTM&H MCQ

Correct answer: B — Ciguatera fish poisoning

Ciguatera fish poisoning (B) is correct. The stem describes a classic ciguatoxin syndrome: ingestion of a large tropical reef predator fish (barracuda) in the Caribbean, an outbreak affecting multiple people who shared the same meal, and onset within hours of gastrointestinal symptoms followed by the pathognomonic neurological feature of hot-cold temperature reversal (dysaesthesia) plus paraesthesiae. Ciguatoxin is produced by the dinoflagellate Gambierdiscus toxicus and bioaccumulates up the reef food chain into large carnivorous fish such as barracuda, grouper and snapper, and the toxin is heat-stable so normal cooking does not neutralise it. The combination of gastrointestinal upset with sensory disturbance and thermal allodynia distinguishes ciguatera from other seafood-associated illnesses and is the key examiner clue. Why the other options are wrong: A. Scombroid poisoning: caused by histamine accumulation in improperly stored fish (typically tuna or mackerel), presenting with flushing, urticaria and a peppery taste, not paraesthesiae or temperature reversal. D. Cholera: causes profuse watery diarrhoea from contaminated water, not fish ingestion, and does not cause paraesthesiae or thermal dysaesthesia. C. Botulism from canned food: presents with descending flaccid paralysis and cranial nerve palsies from Clostridium botulinum neurotoxin, not acute vomiting with temperature reversal, and is linked to improperly canned or preserved food rather than fresh reef fish. E. Tetrodotoxin poisoning: associated with pufferfish (fugu) ingestion, causing rapid ascending paralysis and respiratory failure without the characteristic thermal allodynia of ciguatera. Key point: Gastrointestinal symptoms plus paraesthesiae and hot-cold temperature reversal after eating a large reef fish (barracuda, grouper, snapper) in the tropics is diagnostic of ciguatera fish poisoning.

Reference: TravelHealthPro / Travel Doctor Network, Ciguatera Fish Poisoning, clinical features and reef fish source: https://www.traveldoctor.network/risk/ciguatera-fish-poisoning/