Anaphylactic shock to oysters and white fish with generalized urticaria to prawns and white fish.

Because seafood consumption is moderate-to-high in Spain, allergic reactions to seafood such as fish, crustacea and mollusc are fairly frequent. The clinical features of these reactions depend on the implicated species and whether the reaction is provoked by ingestion, handling or vapor inhalation. Because different species have common antigenic structures, cross-sensitization is frequent, especially between crustaceans and molluscs. Contamination of fish by nematodes (Anisakis) may produce severe reactions. We report the case of a female patient with no personal or family history of allergy who experienced two episodes of anaphylactic shock: the first occurred immediately after eating oysters and the second after ingestion of white fish. The patient also developed generalized urticaria provoked by crustacean (prawns) and white fish. The results of skin prick tests were negative for fish, shellfish, crustacean and oysters while in vitro tests were positive for oyster, prawns, Anisakis, Ascaris and Echinococcus, although stool samples and gastric endoscopy were negative.