Anisakis allergy beyond elimination: High cooked-fish clinical tolerability and diagnostic value of two-stage ani sIgE

BACKGROUND: Anisakis allergy (AA) is a major cause of adult food allergy in Japan. We evaluated the safety of seafood broth, cooked fish, and thawed frozen fish in AA, and the diagnostic value of early Anisakis-specific IgE (Ani sIgE) dynamics. METHODS: We conducted a single-center retrospective cohort study of 44 AA outpatients. Based on clinical tolerability to cooked fish and broth, patients were classified as gastroallergic anisakiasis-like type (GAA-type; asymptomatic with cooked fish/broth; clinically tolerant) or classical anisakis allergy-like type (classical AA-type; symptomatic). Classical AA-type underwent stepwise Oral Fish Clinical Challenge (OFCC) followed by oral tolerability induction (OTI). Ani sIgE was measured in paired serum samples ≤7 days and 1-24 months after onset. RESULTS: Forty-four patients were analyzed; cooked-fish tolerability was 86.4% (38/44), broth tolerability 95.5% (42/44). Among GAA-type (n = 38), all 30/30 who attempted thawed frozen fish clinically tolerated it. Classical AA-type accounted for 6/44 (13.6%); all reactions were Grade 1-2. Stepwise OFCC/OTI enabled symptom-free ingestion under protocol conditions in 5/6 (83.3%); no Grade ≥3 events occurred during OTI. Paired Ani sIgE (n = 26) rose from 1 week to 4 months (peak), then declined; all 10/10 with initial