THE SPECTRUM OF ALLERGY TO SOUTH-AFRICAN BONY FISH (TELEOSTI) - EVALUATION BY DOUBLE-BLIND, PLACEBO-CONTROLLED CHALLENGE

Objective. The aim of this study was to assess the spectrum of allergy to South African bony fish (Class Teleosti), crustaceans and molluscs and to confirm or refute suspected allergy, specifically to bony fish , by double-blind, placebo-controlled food challenge (DBPCFC). Design. Patients were recruited by means of a seafood allergy questionnaire. Subjects with reported allergy to hake, yellowtail, salmon and mackere l were investigated by means of skin-prick tests, RASTs and Western bl ot analysis. For those subjects with test results that were either all negative or equivocal, a definitive diagnosis of clinical sensitivity was made on the basis of DBPCFC.Setting. Volunteer population-based c ohort in the Western Gape. Participants. 105 volunteer subjects with s uspected fish allergy were recruited by advertising in the local press . Main outcome. Species-specific bony fish allergy was confirmed or re futed by DBPCFC. Results. The four most common seafood species reporte d to cause adverse reactions were prawns (46.7%), crayfish (43.8%), ab alone (35.2%) and black mussels (33.3%). The four most common bony fis h species to cause reactions were hake (24.8%), yellowtail (21.9%), sa lmon (15.2%) and mackerel (15.2%). Seven DBPCFCs were performed and tw o open challenges. Skin-prick tests produced one false-negative result . Western blots produced one false-negative and one false-positive res ult. The PAST had a 100% correlation with DBPCFC. Conclusions. Local b ony fish represent a significant cause of clinical reactions to seafoo d in the Western Cape. Although skin-prick tests, RASTs and Western bl otting tests assist in the documentation of an IgE responder state, co nfirmation of clinical sensitivity can only be made with certainty by means of DBPCFC.