ANISAKIS SIMPLEX, A RELEVANT ETIOLOGIC FACTOR IN ACUTE URTICARIA

Anisakis simplex, a parasite of fish and cephalopods, can induce IgE-m ediated reactions. This study aimed to determine the etiologic role of A. simplex in patients affected by urticaria/angioedema (AE) or anaph ylaxis. We studied 100 adult subjects suffering acute episodes of urti caria/AE, by anamnesis, prick tests with A. simplex and fish-mix extra cts, and total and specific IgE to both A. simplex and cod. The follow ing criteria of A. simplex allergy were considered: 1) urticaria/AE wi thin 6 h after fish ingestion; 2) specific IgE to A. simplex; 3) posit ive prick test to A. simplex extract; 4) exclusion of other suspected causes. Double-blind, placebo-controlled food challenge was not carrie d out because ethical considerations forbid challenge with a parasite. Specific IgE to A. simplex (>0.7 kU/l) was found in 22 subjects, but only eight were diagnosed as having A. simplex allergy. Other allergen s were involved in 37 patients, and 55 cases were considered idiopathi c. Specific IgE to fish (>0.7 kU/l) was found in two patients, but onl y one was diagnosed as having fish allergy. We concluded that A. simpl ex is an important etiologic factor in acute urticaria. We suggest tha t it should be considered in cases of urticaria/AE or anaphylaxis, esp ecially after fish ingestion.