31. Egg allergy overview and application to milk allergic children

Egg allergy is the second most common food allergy in young children, although the majority of them become tolerant by school-age. Several allergens have been identified and studies have revealed two subpopulations (children tolerant or not to heated white), depending on the allergen sensitization (ovalbumin or ovomucoid). Clinical adverse reactions to egg may occur in infants or children who have never eaten egg and they may react at first egg ingestion. Immunoglobulin E (IgE)-mediated allergic reactions are the most common type, but other allergic diseases such atopic dermatitis and eosinophilic gastrointestinal disorders have also been related to egg intake, although the underlying mechanism is not well described. Clinical presentations may appear with cutaneous, gastrointestinal, and respiratory symptoms. Egg allergy is also one of the most common causes of severe anaphylaxis. Diagnosis of egg allergy is based on clinical history and presence of specific IgE antibodies to the food, but it can only be verified after performing a challenge test, although this exposure test can be avoided in certain circumstances. Management of egg allergy is based on the avoidance of egg protein intake. Accidental exposures are common and the family must be trained to recognize allergic reactions and to handle the use of the adrenalin self-injector. For those children with confirmed tolerance to cooked egg, only uncooked must be avoided. Some children with ovomucoid-sensitization pattern might tolerate an extensively baked product. This practice not only improves the quality of life for families but also appears to favor the tolerance. Oral tolerance induction is becoming more common and satisfactory results have been reported, even in cases where the final dose cannot be reached. The prevalence of sensitization and allergy to egg is even greater in children with cow’s milk allergy. This sensitization doesn’t mean a relevant clinical allergy and egg must not be avoided without further investigation.