D1.205 - Characterization of a cohort of fish allergic portuguese patients

Fish allergy may affect less than 1% of general population. The majority of fish allergic patients have IgE mediated symptoms and are sensitized to parvalbumin, which can explain cross-reactivity between fish species. In this study we aim to characterize clinically and laboratory a cohort of patients with fish allergy.

Retrospective study in patients with the diagnosis of fish allergy followed in our center from January 2005 to January 2025.Data were collected from the clinical files and the following variables were evaluated: demographic characteristics, clinical symptoms, total IgE, specific IgE to the available fishes, basal tryptase.

We evaluated 124 patients, 61% males, mean age 26.5±15.1 years-old (4-77 years-old). The majority had IgE mediated allergy (92%). Patients developed fish allergy at a mean age of 9.1±16.1 years (6 months-70 years). Anaphylaxis was the most frequent manifestation, followed by cutaneous (36%), gastrointestinal (7%) and respiratory (3%) symptoms. Forty five (36%) patients had symptoms in the first ingestion and 5 (4%) after inhalation. The most frequent fishes involved in reactions were hake (n=48), cod (n=27) and horse mackerel (n=25). Canned fishes were identified as causal agents in 11 patients (10 tuna and 1 sardine). Forty patients tolerated other fishes after the first reaction. Five patients outgrew their fish. 77% had sensitization to multiple fishes confirmed by skin prick tests. Nineteen patients had positive oral food challenges. Laboratorial results are showed in table 1. Regarding comorbidities, 70% had allergic rhinitis, 65% other IgE mediated food allergy, 49% eczema, 34% asthma and 3% eosinophilic esophagitis.

The majority of our patients had IgE mediated fish allergy, with anaphylaxis being the most frequent clinical manifestation. One third of the patients tolerate other fishes, mostly tuna, which suggest that the main sensitization is through parvalbumin. In our cohort, the majority of patients has other atopic diseases, especially allergic rhinitis and other IgE-mediated food allergy.