D3.45 - Oral Food Challenge in children diagnosed with fish allergy. Our clinical experience

Fish allergy is common in children from mediterranean countries, with an estimated prevalence of 0.1–0.5% in Europe, often leading to restrictive diets and nutritional impact. The aim of this study was, to evaluate the reintroduction by oral food challenges (OFC) of the fish involved in the initial allergic reaction and/or alternative fishes in pediatric patients diagnosed with IgE and non IgE-mediated fish allergy, considering clinical features and phylogenetic fish classification.

Retrospective observational study including 38 patients (6 months–16 years) diagnosed with IgE and non IgE mediated fish allergy, evaluated in our allergy day hospital between 2021 and 2024. Tolerance was defined as a negative oral food challenge (OFC) followed by reintroduction of the fish into the diet. OFCs were performed according to the type of reaction (IgE vs. Non IgE mediated) and fish phylogenetic (Perciformes, Clupeiformes, Salmoniformes, Lophiiformes, Gadiformes, and Pleuronectiformes). When possible, OFCs were performed with the fish implicated in the reaction. In cases of non-IgE-mediated reactions and anaphylaxis, the OFC was performed with an alternative fish.

A total of 38 patients were included (22 females/16 males). The mean age of initial reaction was 1.2 years, and the mean age of the first OFC was 3.2 years. Overall, 18 IgE mediated reactions were documented: mucocutaneous 56%, anaphylaxis 33%, and bronchospasm 11%. Non IgE mediated reactions occurred in 20 patients: vomiting 80%, FPIES 10%, and diarrhea 10%. The fish involved were hake (20/38), tuna (6/38), cod (4/38), salmon (4/38), anchovy (2/38), and monkfish (2/38). Patients in whom tuna was the culprit fish, a direct OFC was performed, with 100% tolerance. The remaining data regarding type of reaction, OFC, and tolerance is shown in the table.

100% of patients with IgE mediated mucocutaneous reactions tolerated the culprit fish. In non IgE mediated reactions, 80% (16/20) were able to introduce an alternative fish, and 65% (10/16) of these subsequently tolerated the culprit fish. No OFCs with the culprit fish were performed in cases of anaphylaxis or FPIES. Controlled reintroduction and the use of phylogenetic taxonomy reduced unnecessary restrictive diets.