Harmful effect of immunotherapy in children with combined snail and mite allergy

Background: With respect to allergy, the possibility of cross-reactivity between snail and mite is well recognized, and anecdotal reports suggesting that allergen immunotherapy with mite extract can worsen snail-induced allergy exist. Objective: We describe the effect of immunotherapy in 4 children with snail-mite allergy. Methods: Four children (1 boy and 3 girls; 9-13 years of age) had consistent clinical histories (mild immediate respiratory symptoms after ingestion) and positive skin reactions for allergy to snail. They also had mite-induced asthma and were therefore prescribed subcutaneous specific immunotherapy and subsequently followed. Results: Several months (8-25) after starting immunotherapy, all children experienced life-threatening reactions, anaphylaxis, and respiratory failure after inadvertent ingestion of snail. Skin reactivity to the fresh food increased in all patients. Conclusions: This observation confirms that in patients with combined mite-snail allergy, immunotherapy should be avoided.