Not all shellfish "allergy" is allergy!

Tropomyosin is the major allergen and is responsible for cross-reactivity between members of the shellfish family, particularly among the crustacea. Newly described allergens and subtle differences in the structures of tropomyosin between different species of shellfish could account for the discrepancy between in vitro cross-antigenicity and clinical cross-allergenicity. The diagnosis requires a thorough medical history supported by skin testing or measurement of specific IgE level, and confirmed by appropriate oral challenge testing unless the reaction was life-threatening.Management of shellfish allergy is basically strict elimination, which in highly allergic subjects may include avoidance of touching or smelling and the availability of self-administered epinephrine. Specific immunotherapy is not currently available and requires the development of safe and effective protocols.Seafood consumption has increased in popularity and frequency worldwide. The largest consumer is China, followed by Japan and United States of America. In 2009, Americans ate an average of 15.8 pounds of fish and shellfish per capita, with shrimp being the top choice at 4.1 pounds [1]. The increased production and consumption of seafood has been accompanied by increasing reports of adverse reactions to seafood. Such reactions can be immune-mediated allergic reactions or non-immunologic, with both presenting with similar symptoms.Shellfish is one of the leading causes of food allergy in adults and is a common cause of food-induced anaphylaxis. In an international survey using a questionnaire administered to 17,280 adults (aged 20-44 years) from 15 countries, symptoms related to seafood were reported to be caused by shrimp in 2.3%, oyster in 2.3%, and fish in 2.2% [2]. In the United States, a telephone survey of 14,948 individuals revealed that 2-3% believed to have seafood allergy: 2.2% to shellfish and 0.6% to fish [3]. Shellfish allergy was much lower in children than in adults (0.5 vs 2.5%