Allergic contact urticaria caused by raw prawns and shrimps: three cases.

Contact urticaria from raw prawns and shrimps was suspected in three housewives with hand eczema who visited our clinic. A practice skin test in which patients stripped the shells from raw prawns and shrimps was positive, but an intradermal skin test with an allergen extracted from a mixture of prawns and shrimps was negative. Results of skin tests with fresh extracts of raw prawns and shrimps were positive. The RAST with a paper disc method with use of a raw prawn and shrimp as antigens was also positive in these three patients. It is evident from the results obtained that some common substances causing a local urticaria exist in raw prawns and shrimps.