A gentleman Mr X visited me the other day in the surgery and as he was due to depart for a holliday at a seaside retreat in Mauritius he wanted to revisit and episode of anaphylaxis he experienced about 10 years prior when his throat closed up and he had difficulty breathing after eating calamari.
He had since not eaten any seafood except tuna and salmon and hake to which he experienced no symptoms. Testing with a seafood mix IgE showed sensitization with high levels of antibodies to molluscs and shrimp species and langoustines. Calamari is a class of the Phylum Molluscs and the presumed allergy is to the protein Tropomyosin which is also found in crustaceans. Molluscs include abalone, snail , oyster, mussel , squid and octopus.
The patient should therefore avoid all crustaceans which include crab, rock lobster, lobster, prawn and barnacle aswell as all molluscs.
Futhermore due to the severity of his reaction and antibody level he will be advised to carry an epipen which may be useful in case of accidental contamination at a seafood restaurant with either crustaceans or crayfish and this could alleviate a potentially life threatening anaphylaxis.
The major allergens responsible for ingestion related allergic reactions are tropomyosin. In addition to tropomyosin molluscs contain other well less characterized allergens. Fish allergens are parvalbumin small calcium binding proteins and less common allergens such as collagen from the skin of the fish .
