Significations et usages de Egg_allergy

From Wikipedia, the free encyclopedia

Egg allergy is a type of food allergy. It is a hypersensitivity to dietary substances from the yolk or whites of eggs, causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people around the world.^[1]

Egg allergy appears mainly, but not exclusively, in children. In fact, it is the second most common food allergy in children.^[2] (The most common is cows' milk allergy). It is usually treated with an exclusion diet and vigilant avoidance of foods that may be contaminated with egg. The most severe food allergy reaction is called anaphylaxis^[3] and is an emergency situation requiring immediate attention and treatment with epinephrine. The Asthma and Allergy Foundation of America estimates that most children outgrow egg allergy by the age of five, but some people remain allergic for a lifetime.^[4]

Antigens

Most people who are allergic to hen's eggs have antibodies which react to one of four proteins in the egg white:^[5] ovomucoid, ovalbumin, ovotransferrin, and lysozyme; ovomucoid, also called Gal d 1, is the most common target of immune system attack.^[5] The egg yolk contains several potential antigens: livetin, apovitillin, and vosvetin.

Some research on lysozyme and ovotransferrin suggests that, perhaps, one of the causes of the allergy is from the chelating capacity of the proteins with metals, especially those of heavy metals.^{[6][7][8][9][10]} However, little scientific information is available currently on the direct relationships of the heavy metals in hen eggs and egg allergy.

A person who reacts only to a protein in the egg yolk may be able to easily tolerate egg whites, and vice versa. Some people will be allergic to proteins in both the egg white and the egg yolk. Egg yolk allergies may be somewhat more common in adults.^[5] A small number of people who are allergic to eggs will develop an allergy to chicken or other poultry meats.^[5]

Diagnosis

Diagnosis is generally made through a combination of skin prick testing or blood testing and detailed records of everything that the person eats.

Treatment

There is currently no cure for Egg allergy.Most people who are allergic to eggs avoid eating any form of egg or egg component.

Prognosis

In a study presented at the 2007 American Academy of Allergy, Asthma, and Immunology (AAAAI) meeting, 50% of patients outgrew egg allergy by age 17. Of those patients who outgrew it, 45% did so by age 5. Children who outgrew the allergy tended to have peak IgE levels at around age one, which then decline.^[11]

Vaccines

The flu vaccine is typically made using eggs to incubate the vaccine. Egg-allergic individuals may react to the vaccine. If an individual is unable to take the vaccine, vaccinating all other members of their family can help protect them from the flu.

Individual batches of flu vaccine may vary in their egg content. An allergist may give an egg-allergic individual a skin test to the flu vaccine, to see if receiving the flu shot is possible. If the skin test is negative, then a small amount of the vaccine is administered. If no reaction occurs after a waiting/observation period, then the rest of the shot is given, followed by a second observation period to continue to monitor for reactions.^{[citation needed]}

Egg proteins can also be found in yellow fever vaccine and MMR vaccine.^[12] The quantity of egg protein in a dose of MMR vaccine is approximately 40 pg (much lower than in influenza vaccine, which contains approximately 0.02-1.0 ug), and this is believed to be associated with a much lower risk.^[13]

Cooking without eggs

In cooking, eggs are an emulsifier—they help ingredients to mix smoothly. It is possible to buy a commercial egg replacer, which may be made from ingredients like potato starch and tapioca. Applesauce also works as an emulsifier. Half a cup of apple sauce can replace one egg in most recipes.^{[citation needed]}

Most people find it necessary to strictly avoid any item containing eggs, including:^[14]

Ingredients that sometimes include egg are:

• Artificial flavoring
• Lecithin
• Natural flavoring
• Nougat

Egg white intolerance

Egg whites, which are potent histamine liberators, also provoke a non-allergic response in some people. In this situation, proteins in egg white directly trigger the release of histamine from mast cells on contact.^[15][16] Because this mechanism is classified as a pharmacological reaction, or "pseudoallergy",^[15] the condition is considered a food intolerance instead of a true IgE-based allergic reaction.

The response is usually localized, typically in the gastrointestinal tract.^[15] Symptoms may include abdominal pain, diarrhea, or any symptoms of histamine release. It can result in an anaphylactoid reaction, which is clinically indistinguishable from true anaphylaxis, if sufficiently strong.^[16]

Some people with this condition tolerate small quantities of egg whites.^[17] They are more often able to tolerate well-cooked eggs, such as found in cake or dried egg-based pasta, than loosely cooked eggs, such as fried eggs or meringues, or uncooked eggs.^[17]

Notable people allergic to eggs

Famous people allergic to eggs include:

• NFL player Drew Brees ^[18]

See also

• Allergy
• Anaphylaxis
• Asthma
• Dairy product
• Lysozyme

References