Although egg allergy prevails in pediatric population, some studies have described the persistence or newly onset egg sensitization through adults . A failure in oral tolerance or a breakdown in previously acquired tolerance results in food hypersensitivity. Egg allergy is frequently observed during the first years of life, according to its alimentary introduction. There is a possible resolution of egg allergy within 10–15 years from the diagnosis. Symptoms include early onset of IgE-mediated urticaria, eczema, abdominal pain and vomiting. In some more severe cases anaphylaxis with dyspnea and hypotension can occur. Non-IgE mediated symptoms include eosinophilic diseases of the gut or egg-induced enterocolitis [2, 3]. Consumption of baked egg by raw egg allergic children does not seem to either induce or accelerate the development of tolerance in this population . There is evidence of a strong association between sensitization to egg during infancy and, later, to inhalant allergens.
The rare adult-onset egg allergy is often associated with previous personal history of atopy or other food intolerances [5,6,7]. Some studies have shown that stress conditions or alteration of intestinal microbiota could be responsible for the loss of tolerance toward some food antigens . Intestinal inflammatory disorders, such as Crohn disease, celiac disease, or ulcerative colitis favor the development of food allergy by altering intestinal permeability. It has been reported a case of late-onset egg allergy following the diagnosis of Hodgkin’s lymphoma and start of chemotherapy and the authors speculated an alteration involving bowel mucous membrane .
Diagnosis of egg allergy includes anamnesis, skin prick tests and serum specific IgEs . The most significant antigenic components of egg white are ovomucoid (Gal d 1—thermo stable), ovalbumin (Gal d 2—thermolabile), ovotransferrin (Gal d 3), and lysozime (Gal d 4). Depending on the sensitization pattern, patients with egg allergy can manifest symptoms with cooked or raw egg. In some patients a relationship between hypersensitivity secondary to bird antigens exposure and allergy to egg yolk has been documented . This is known as bird-egg syndrome . It derives from the sensitization to the chicken serum protein called alpha livetin (Gal d 5), that is also represented in egg yolk. It is characterized by respiratory and gastrointestinal symptoms after egg intake or after exposure to feathers and droppings of birds. Allergy to other aeroallergens is frequently documented in individuals with bird-egg syndrome.
Currently, there is active research on trying oral immunotherapy to desensitize people to egg allergens [11,12,13].