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Cross-reactivity between terrestrial snails (Helix species) and house-dust mite (Dermatophagoides pteronyssinus). I.
D A Vuitton1, F Ranc e, M L Paquin
1Research Group on Allergic Diseases, University of Franche-Comté (SERF), University Hospital, Besançon, France.
Abstract:
Clinical reports have suggested an unusual frequency in the number of patients with food allergy to snails who are also allergic to the house-dust mite (HDM). As allergy to HDM is one of the most frequent sensitizations in atopic patients of Western countries, evaluation of the relevance of the concomitant sensitization to Dermatophagoides pteronyssinus and to snails is an important consideration. To evaluate the responsibility of different snail components and of snail mites for inducing in vivo hypersensitivity in patients allergic to HDM, the in vivo reactivity of patients with clinical symptoms after ingestion of snails was assessed by skin prick tests with extracts and hemolymph from four different Helix species snails, and extracts from the snail parasitic mite, Riccardoella limacum. In addition, to obtain epidemiologic data on cosensitization to HDM and snails in allergic patients, the frequency of snail sensitization and its relationship to HDM sensitization were determined in a population of 169 allergic children. All patients allergic to snails had positive skin prick tests to the snail extracts and none to R. limacum extract. The number of positive skin reactions did not significantly differ whatever the species, snail part, or heating procedure used. The strongest reactions were obtained with Helix pomatia (Burgundy snail). Among the 169 prospectively tested children, 38 had a positive prick test to snail extracts; 79% of the snail-sensitized children had sensitization to HDM; and 31% of the children allergic to HDM were found to be sensitized to snails. These results show that snail components, and not the mite R. limacum, were responsible for the in vivo hypersensitivity. These snail components reacting in vivo are present in different parts of snails, including the hemolymph. One-third of the children allergic to HDM were sensitized to snails without any previous ingestion of snails: this observation suggests that HDM was the sensitizing agent and that the cross-reaction could be clinically relevant in countries where eating snails is common.
Insights
Food allergy to snails is often linked with house-dust mite (HDM) allergy. Snail components, not mites, trigger allergic reactions, suggesting cross-reactivity may be clinically significant.
Area of Science:
- Immunology
- Allergology
- Epidemiology
Background:
- Clinical observations suggest a high co-occurrence of food allergy to snails and house-dust mite (HDM) allergy.
- HDM allergy is a prevalent sensitization in Western countries, making the link with snail allergy a significant consideration.
- Understanding this co-sensitization is crucial for diagnosing and managing allergic conditions.
Purpose of the Study:
- To investigate the role of snail components and snail mites in causing in vivo hypersensitivity in patients allergic to HDM.
- To determine the epidemiological data on co-sensitization between HDM and snails in allergic individuals.
- To assess the clinical relevance of cross-reactivity between HDM and snail allergens.
Main Methods:
- Skin prick tests were performed on patients with clinical snail ingestion symptoms using extracts and hemolymph from four Helix species snails.
- Extracts from the snail parasitic mite, Riccardoella limacum, were also used for skin prick testing.
- A population of 169 allergic children was prospectively studied to determine the frequency of snail sensitization and its relationship to HDM sensitization.
Main Results:
- All patients allergic to snails showed positive skin prick tests to snail extracts, but not to the mite R. limacum extract.
- Reactivity to snail extracts was consistent across different snail species, parts, and heating procedures, with Helix pomatia yielding the strongest reactions.
- Among 169 children, 38 (22.5%) were sensitized to snails. Of these, 79% were also sensitized to HDM. Conversely, 31% of HDM-allergic children were sensitized to snails.
Conclusions:
- Snail components, not the mite R. limacum, are responsible for in vivo hypersensitivity reactions.
- Allergenic snail components are present in various parts of the snail, including hemolymph.
- A significant proportion of HDM-allergic children were sensitized to snails without prior snail ingestion, indicating potential cross-reactivity and clinical relevance, especially in regions where snails are consumed.