Hooked! The fishy truth of persistent fish allergy

Published online December 26, 2024

Fish allergy affects people of all ages, but not everyone reacts the same way. Some individuals outgrow it, while others remain allergic and at risk of experiencing severe allergic reactions. The main culprit allergen is parvalbumin, a protein found in fish meat that is resistant to heat and digestion. This study analyzed individuals with persistent fish allergy and determined their reactivity thresholds, that is, how much fish protein is needed to trigger an allergic reaction.

A study published in The Journal of Allergy and Clinical Immunology: In Practice, by Fernandez-Rivas and colleagues, investigated the severity and reactivity thresholds in patients with persistent fish allergy sensitized to parvalbumin. The research, conducted in six European allergy centers, included 42 individuals aged 12 to 65 years who reported allergic reactions to fish, and had positive skin prick tests and serum specific IgE to several fish species and to fish parvalbumin. These patients underwent titrated double-blind placebo-controlled food challenges with cod to confirm fish allergy and to determine reactivity thresholds.

This study aimed to establish the severity and reactivity thresholds of patients with persistent fish allergy linked to parvalbumin sensitization, and to analyze the safety of the oral fish challenges used for this purpose.

Of the 42 participants, 30 (71%) were confirmed to have a persistent fish allergy. Most patients had a first reaction to fish in early childhood, with a median duration of fish allergy of 23 years by the time of the study. While 70% of these patients had experienced severe allergic reactions, including potentially life-threatening anaphylaxis, food challenges proved to be safe, with most reactions (74%) during challenges being oral and mild systemic reactions involving one organ, with only one case of anaphylaxis (4%). The study also found that men were more likely to have severe reactions, and that even tiny amounts of fish protein (as little as 1 mg) could trigger objective symptoms in 10% of the patients.

This study shows that adolescent and adult patients with persistent fish allergy linked to parvalbumin sensitization have low reactivity thresholds and are at risk of experiencing severe allergic reactions in real-life settings. These findings emphasize the importance of oral food challenges for an individualized fish allergy management, and the need for new treatment options for these patients.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, providing practical information for doctors and patients.

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