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Patients suffering anaphylactic reactions after parasitized fish consumption have been reported in Spain in recent years. This reaction is different from the well-known acute or chronic anisakiasis and causes intolerance to parasitized fish ingestion, even after appropriate cooking. High specific IgE values are usually found in these subjects. IgE immunoblotting is now needed to confirm the presence of specific IgE directed to several parasite antigens in order to exclude cross-reactions. Positive specific IgG4 by immunoblotting was found in 60% of the patients, as well as in patients with anisakiasis, and probably reflected recent contact with the parasite proteins. The most specific response of IgE antibodies was directed to low-molecular-mass antigens of the parasite. Therefore, recombinant or purified antigens for in vivo and in vitro use will in future overcome some of the problems found in the diagnosis of sensitized patients.

Background: The fish parasite Anisakis simplex is the etiologic agent of anisakiasis and induces IgE-mediated reactions. Skin prick tests (SPTs) and the measurement of specific IgE to A. simplex were, in our experience, not valid tools with which to discriminate between allergic and nonallergic patients because many control subjects also had positive results. Objective: The study was carried out to assess the usefulness of IgE immunoblotting in the diagnosis of allergy to A. simplex. Methods: We have studied 61 patients with acute symptoms of urticaria, angioedema, or anaphylaxis and positive specific IgE to A. simplex . According to the anamnesis, time interval between ingestion of fish and clinical onset of symptoms, and exclusion of other causes of allergy, three different groups of patients were established: group A (allergic), group NA (nonallergic), and group D (doubtful). Fifty-one healthy donors were included as control subjects (group C). IgE immunoblotting with A. simplex whole-body extract was performed in all patients and control subjects. Results: Four patterns of immunoblotting were observed: type 1, with a group of several bands of medium molecular weight and others of low molecular weight; type 2, two or more bands of medium molecular weight; type 3, only one band of medium molecular weight; type 4, without any band. There was a significant predominance of blotting type 1 in group A and type 4 in group C. Conclusion: These data suggest that IgE immunoblotting is the most useful approach to A. simplex allergy diagnosis. (J Allergy Clin Immunol 1997;99:497-501.)

Anaphylactic reactions after parasitized fish consumption are mediated by an IgE response. However, positive skin tests and specific IgE can also be found in many asymptomatic subjects who recognize a single medium-mol.-wt. antigen by IgE immunoblot. The study aimed to find out whether this unspecificity was due to the carbohydrate moieties of parasite antigens. Sixty-two patients with suspected parasite allergy, 51 blood donors, 18 bakers, and 38 atopic patients were studied by blotting. Parasite proteins were treated with periodate. Several selected sera were inhibited with a crude wheat extract and fungal amylase. Twelve patients (19%), eight donors (16%), six bakers (33%), and one atopic patient (3%) recognized a single medium-mol.-wt. band in blotting and should be considered false-positive. This band was periodate-sensitive, but specific IgE to this allergen could not be inhibited by a wheat extract nor by fungal amylase and was clinically irrelevant. Diagnosis of Anisakis simplex hypersensitivity by skin tests and/ or specific IgE values should always be confirmed by specific IgE immunoblotting in order to detect the presence of clinically unrelated antibodies directed to periodate-sensitive allergens. These allergens are probably not a carbohydrate moiety of a parasite glycoprotein.

Del Pozo MD, Audicana M, Diez JM, Munoz D, Ansotegui IJ, Fernandez E, Garcia M, Etxenagusia M, Moneo I, Fernandez de Corres L. Anisakis simplex, a relevant etiologic factor in acute urticaria. Anisakis simplex, a parasite of fish and cephalopods, can induce IgE-mediated reactions. This study aimed to determine the etiologic role of A. simplex in patients affected by urlicaria/angioedema ‘AE’ or anaphylaxis. We studied 100 adult subjects suffering acute episodes of urticaria/AE, by anamnesis, prick tests with A. simplex and fish-mix extracts, and total and specific IgE to both A. simplex and cod. The following criteria of A. simplex allergy were considered: 1’ urticaria/AE within 6 h after fish ingestion; 2’ specific IgE to A. simplex; 3’ positive prick test to A. simplex extract; 4’ exclusion of other suspected causes. Double-blind, placebo-controlled food challenge was not carried out because ethical considerations forbid challenge with a parasite. Specific IgE to A. simplex‘