Unexpected cause of urticaria

A 30-year-old man presented with acute generalised urticaria (Figure, A) 6 hours after ingestion of raw fish. While most adult food allergies occur within 1–2 hours of ingestion, allergy to the live fish parasite Anisakis simplex which has penetrated the gastrointestinal mucosa manifests 1 hour to a few days after ingestion.1 Emergency upper endoscopy detected the live larva in the stomach (Figure, B) and disinfestation resolved his symptoms. Allergy to A. simplex can be confirmed by testing for allergen-specific IgE or skin prick testing with Anisakis extract. Gastrointestinal anisakidosis can be an unexpected cause of urticaria owing to delay between the ingestion of fish and the appearance of symptoms. While most cases of anisakidosis currently occur in Japan, this may become an increasing problem in Australia due to increasing consumption of sushi and sashimi.2

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