Contemporary issues in food allergy: seafood toxin-induced disease in the differential diagnosis of allergic reactions.

Seafood, including fish, shrimp, lobster, crab, crayfish, mussel, and clam are among the most frequent causes of food allergy. Seafood poisoning, including reactions to natural toxins, frequently masquerades as an allergic reaction on presentation. Ingestion of contaminated shellfish results in a wide variety of symptoms, depending on the toxins present, their concentrations in the shellfish, and the amount of contaminated shellfish consumed. Five types of shellfish poisoning have been identified clearly including paralytic, neurotoxic, diarrhetic, amnestic, and azaspiracid shellfish poisonings. Based on the presence or absence of the toxin at the time of capture, fish poisoning can be considered conceptually in two categories. In ciguatera and puffer fish poisoning, the toxin is present in live fish, whereas in scombroid, it is produced only after capture, in the fish flesh, by contaminating bacteria because of improper refrigeration. Most shellfish-associated illness is infectious in nature (bacterial or viral), with the Norwalk virus accounting for most cases of gastroenteritis.