Fish allergy: is cross-reactivity among fish species relevant? Double-blind placebo-controlled food challenge studies of fish allergic adults

Background: Allergic reactions to fish are a common cause of food allergy i n many areas of the world where fish is a major source of protein. Although different species of fish may be consumed, possible cross-reactivity has r eceived limited investigation. Objective: The aim of this study was to assess potential cross-reactivity t o different species of fish species using double-blind, placebo-controlled food challenges (DBPCFC) in fish-allergic adults and to compare skin test a nd RAST reactivity with the challenge response. Methods: Nine skin prick test and/or RAST-positive adult individuals with h istories of an immediate-type reaction following fish ingestion were challe nged with different fish species using double-blind, placebo-controlled foo d challenge. Results: Of a total of 19 double-blind, placebo-controlled fish challenges performed, 14 challenges (74%) resulted in the induction of objective signs that were consistent with an IgE-mediated response, The most common sign o bserved was emesis (37%); the most prevalent subjective symptoms reported w ere compatible with the oral allergy syndrome (84%). Three subjects reacted to at least three fish species and one subject reacted to two fish species tested. In regard to the positive challenges, predictive accuracy of skin prick test and RAST was 84% and 78%, respectively. Conclusion: Our results indicate that clinically relevant cross-reactivity among various species of fish may exist. Advising fish-allergic subjects to avoid all fish species should be emphasized until a species can be proven safe to eat by provocative challenge.