Egg also known as Anda (Hindi), Endu (Gujrati), Muttai (Tamil), Mutta (Malyalam), Gruddu (Telugu) is one of the most important allergens in childhood feeding but it’s allergy changes the quality of life.
Egg allergy affects about 0.05% of our population.
- Egg allergy is mainly caused by 4 allergens of the many proteins present in egg white.
- 1. Ovomucoid (Gal d 1): is the most allergenic and dominant allergen found in hen’s egg white and reacts from both raw and cooked egg.
- 2. Ovalbumin (Gal d 2): is the most abundant (58%) protein in the egg white and is 2nd most common allergen causing egg allergy. Patients allergic to Gal d 2 are able to tolerate cooked egg as this protein is heat labile.
- 3. Ovotransferrin (Gal d 3): are heat resistant.
- 4. Lysozyme (Gal d 4): are less allergenic.
- In egg yolk, alpha-livetin (chicken serum albumin, Gal d 5) is the major allergen, also responsible for bird-egg syndrome. Yolk glycoprotein 42 is the another important allergen present in egg yolk.
Cross reactivity: have been reported between hen’s egg and other bird eggs (turkey, duck, goose, seagull and quail). Few egg allergy patients also cross react with chicken meat due to chicken serum albumin.
Symptoms: egg allergy is the 2nd most common food allergy (1st is cow’s milk allergy) and it is the most common allergy in children with atopic dermatitis. Egg allergy is mostly seen in childhood rarely in adults. Children often tend to outgrow their condition in adulthood.
Egg allergy causes conditions such as itching, atopic dermatitis, rhinitis, conjunctivitis, bronchial asthma, angio-oedema, laryngeal oedema, urticaria, allergic eosininophilic gastroenteritis and anaphylaxis.
Bird-egg syndrome is an IgE-mediated hypersensitivity disorder wherein a human develops an allergy to egg yolk, specifically to serum albumin, following sensitisation to inhalant avian antigens derived from sources such as bird’s blood serum, feathers, droppings and dander.
It has been found that eggs heated in the presence of another substance such as wheat have lesser IgE reactivity as compared to eggs heated alone.