D1.01 - Anaphylaxis After Crayfish Consumption with Strong Anisakis simplex Sensitization

Although crustacean allergy is usually caused by tropomyosin, atypical presentations may indicate sensitisation to non-canonical proteins or cross-reactivity with Anisakis simplex. When clinical reactions occur despite negative results for specific IgE to crustaceans, molecular profiling is essential to determine whether the cause is a crustacean protein, a shared allergen or hidden Anisakis contamination.

A 49-year-old man experienced an anaphylactic reaction minutes after eating fried crayfish. He felt dizziness, generalised itchiness, facial flushing, and periorbital erythema, and required emergency medical treatment. A complete allergy work-up was performed, including skin prick testing and prick-by-prick testing with fresh raw or cooked prawn and crayfish. Standard extraction was used to obtain protein extracts, which were analysed for protein and allergenic profiles using SDS-PAGE and Western blot, respectively.

Skin prick testing showed a positive result only for Anisakis, while prick-by-prick testing revealed weak positivity for raw, and cooked prawn, and strong positivity for cooked prawn head. Serum IgE revealed a significantly high level of Anisakis IgE (29.7 kU/L), with no IgE present for shrimp, lobster, mussel, cod, or squid. Total IgE was found to be 137.6 kU/L, with tryptase at 5 µg/L. Western blot analysis revealed the presence of a ~75kDa band in all extracts, alongside multiple IgE-reactive bands in Anisakis, including a ~130 kDa band consistent with paramyosin (Ani s 2). 

The clinical and molecular findings support the idea that Anisakis-driven sensitisation is the underlying mechanism of the reaction. This could be due to the presence of a shared 75kDa heat-stable allergen in both crayfish and Anisakis, or due to cross-reactive epitopes derived from Anisakis contamination.