Asthma after consumption of snails in house-dust-mite-allergic patients: A case of IgE cross-reactivity

A group of 28 patients from Italy was studied who had asthma after consumption of snail. All patients also had asthma and/or rhinitis caused by house-dust mite. RAST analyses confirmed the combined sensitization to snail and mite. In a few sera, IgE antibodies reactive with other foods of invertebrate origin (mussel and shrimp) were detected. RAST inhibition showed that most IgE antibodies against snail were cross-reactive with house-dust mite. In contrast, the mite RAST was not significantly inhibited by snail. This indicates that house-dust mite was the sensitizing agent. Immunoblot analyses revealed multiple bands in snail extract recognized by IgE. In contrast to what has been described for crossreactivity between shrimp and mite, tropomyosin played only a minor role as a cross-reactive allergen In these patients. The observations in this study indicate that snail consumption can cause severe asthmatic symptoms in house-dust-mite-allergic patients. It might, therefore, be advisable to screen mite-allergic asthma patients for allergy to snail and other invertebrate animal foods.