Hen's Egg Allergy

Egg allergy is one of the most frequent food allergies in infants and young children. The prevalence of egg allergy is estimated to be between 1.8 and 2% in children younger than 5 years of age. The reactions are mainly mediated by IgE and partially by non-IgE or are a mix of both types. Egg white contains more than 20 different proteins and glycoproteins. Ovomucoid (Gal d 1), ovalbumin (Gal d 2), conalbumin (ovotransferrin) (Gal d 3) and lysozyme (Gal d 4) have been identified as major allergens in hen's egg. Alpha-livetin (Gal d 5) is thought to be a main egg yolk allergen responsible for bird-egg syndrome. The diagnosis of egg allergy is based on history taking, antigen-specific IgE measurements, such as the skin prick test, in vitro antigen-specific blood IgE tests and histamine release tests, and oral food challenges. The measurements of specific IgE to ovomucoid and its linear epitopes are more useful in the diagnosis of heated egg allergy and in the prediction of prognosis. Currently, the management of egg allergy is essentially minimal elimination based on the correct identification of the causative allergen. Although oral immunotherapy is promising as a tolerance induction protocol, several questions and concerns still remain, predominantly regarding safety.