Egg allergy is a type of food allergy. It is a hypersensitivity to one or more of the proteins from the yolk or whites of chicken eggs, causing an overreaction of the immune system. People with an allergy to chicken eggs may also be allergic to other types of eggs, such as goose, duck, turkey or quail. The body manifests either an antibody-based immune response or a cell-based immune response to these allergens. Antibody responses are usually rapid and can involve anaphylaxis, a potentially life-threatening condition which requires treatment with epinephrine. Cell-mediated responses take hours to days to appear.
A wide variety of foods can cause allergic reactions, but in the United States 90% of allergic responses to foods are caused by cow's milk, eggs, wheat, shellfish, peanuts, tree nuts, fish, and soy beans. The Food Allergen Labeling and Consumer Protection Act (FALCPA) of 2004 requires that the label of a food that contains an ingredient that is or contains protein from these eight major food allergens declare the presence of the allergen in the manner described by the law. Lists can be different in different countries. The Japanese Guideline for Food Allergy counts buckwheat and fruit in a top ten list. The European Union requires labeling for the same eight as the United States plus celery, mustard, lupin seeds, sesame seeds, sulfites (preservative for wine), plus molluscs.
Egg allergy appears mainly in children, but can persist into adulthood. In the United States it is the second most common food allergy in children after cow's milk. Most children outgrow egg allergy by the age of five, but some people remain allergic for a lifetime. It is usually treated with an exclusion diet and vigilant avoidance of baked foods such as cake or cookies that contain eggs as an ingredient. There is not a scientific consensus as to whether avoidance of developing an allergy may be partly achieved through early introduction of the eggs to the diet of babies at ages 4-6 months.
Maps, Directions, and Place Reviews
Mechanisms
Most people who are allergic to hen's eggs have antibodies which react to one of four proteins in the egg white: ovomucoid, ovalbumin, ovotransferrin, and lysozyme; ovomucoid, also called Gal d 1, is the most common target of immune system attack. The egg yolk contains several potential antigens: livetin, apovitillin, and phosvitin.
A person who reacts only to a protein in the egg yolk may be able to easily tolerate egg whites, and vice versa, although it is difficult to separate yolks so that there is no egg white attached. 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. A small number of people who are allergic to eggs will develop an allergy to chicken or other poultry meats.
Non-allergic egg white intolerance
Egg whites, which are potentially histamine liberators, also provoke a nonallergic response in some people. In this situation, proteins in egg white directly trigger the release of histamine from mast cells on contact. Because this mechanism is classified as a pharmacological reaction, or "pseudoallergy", the condition is considered a food intolerance instead of a true immunoglobulin E (IgE) based allergic reaction.
The response is usually localized, typically in the gastrointestinal tract. Symptoms may include abdominal pain, diarrhea, or any symptoms of histamine release. If sufficiently strong, it can result in an anaphylactoid reaction, which is clinically indistinguishable from true anaphylaxis. Some people with this condition tolerate small quantities of egg whites. 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.
How To Get Rid Of Allergy Video
Diagnosis
Diagnosis of egg allergy is based on the person's history of allergic reactions, skin prick test (SPT), patch test and measurement of egg-specific serum immunoglobulin E (IgE or sIgE). Confirmation by double-blind, placebo-controlled food challenges. SPT and sIgE have sensitivity greater than 90% but specificity in the 50-60% range, meaning these tests will detect an egg sensitivity, but will also be positive for other allergens. For young children, attempts have been made to identify SPT and sIgE responses strong enough to avoid the need for a confirming oral food challenge.
Prevention and treatment
When eggs are introduced to an infant's diet is thought to affect risk of developing allergy, but there are contradictory recommendations and guidelines. A 2016 review acknowledged that introducing peanuts early appears to have a benefit, but stated "The effect of early introduction of egg on egg allergy are controversial." A meta-analysis published the same year supported the theory that early introduction of eggs into an infant's diet lowers risk, and a review of allergens in general stated that introducing solid foods at 4-6 months may result in the lowest subsequent allergy risk. However, an older consensus document from the American College of Allergy, Asthma and Immunology recommended that introduction of chicken eggs be delayed to 24 months of age.
Prevention of egg-allergic reactions means avoiding eggs and egg-containing foods. Food companies produce egg substitutes, egg-free mayonnaise and other replacement food that are free of egg proteins. People with severe allergic reactions to eggs, such as anaphylaxis are advised to carry injectable epinephrine for use in emergency.
There is active research on trying oral immunotherapy (OIT) to desensitize people to egg allergens. A Cochrane Review of four clinical trials concluded that OIT can desensitize people, but it remains unclear whether long-term tolerance develops after treatment ceases, and 69% of the people enrolled in the trials had adverse effects. The authors concluded there was a need for standardized protocols and guidelines prior to incorporating OIT into clinical practice. A second review noted that allergic reactions, up to anaphylaxis, can occur during OIT, and recommends this treatment not be routine medical practice. A third review limited its scope to trials of baked egg-containing goods such as bread or cake as a means of resolving egg allergy. Again, there were some successes, but also some severe allergic reactopms, and the authors came down on the side of not recommending this as treatment.
Cooking without eggs
In cooking, eggs are multifunctional: they may act as an emulsifier to reduce oil/water separation (mayonnaise), a binder (water binding and particle adhesion, as in meatloaf), or an aerator (cakes, especially angel food). Some commercial egg replacers can substitute for particular functions (potato starch and tapioca for water binding, whey protein for aeration or particle binding, or soy lecithin or avocados for emulsification). Alfred Bird invented egg-free Bird's Custard, the original version of what is known generically as custard powder today.
Most people find it necessary to strictly avoid any item containing eggs, including:
Ingredients that sometimes include egg protein include: artificial flavoring, natural flavoring, lecithin and nougat
Prognosis
In a study presented at the 2007 American Academy of Allergy, Asthma, and Immunology (AAAAI) meeting, 50% of people 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.
Vaccine hazard
The flu vaccine is typically made using chicken embryo, and as a result the final vaccine does contain egg proteins. Egg-allergic individuals may react to egg protein(s) in the vaccine (or to gelatin or neomycin if they are allergic to that). If an individual is unable to take the vaccine, vaccinating all other members of their family can help protect them from the flu (see Herd immunity).
Different brands and even individual batches of flu vaccine do vary in their egg protein content. Allergists formerly used skin testing with flu vaccine to predict if receiving the flu shot might be safe, but the results of this type of testing are totally unpredictive and this type of testing should be abandoned. Instead, the age-appropriate immunization material containing the lowest amount of egg proteins should be chosen, then a 1/10 dose should be given followed by a 30-minute observation period in a medical setting fully equipped to treat any possible reaction. Ovalbumin is usually used as a marker for the egg proteins. Vaccines available as recently as 2010 in the US contained up to 21 µg of ovalbumin per 0.5 mL dose. In 2011 the ovalbumin content varies from less than 5.0 µg/dose down to less than 0.05 µg/dose, depending on the brand. One study done on 83 egg allergic patients resulted in a lack of serious reactions at doses of ovalbumin ranging from 0.10 µg to 0.60 µg. Thus, some brands available in the US after 2011 are probably safe for most egg allergic patients (administered with caution), but others may not be. For reference modern MMR vaccine (which is generally accepted now to be well tolerated by egg allergic patients, but which is still given with caution) was shown in a 2009 study reported in the BMJ to contain 0.0005 to 0.0010 µg/dose (0.5 to 1.0 ng/dose).
Egg proteins can also be found in yellow fever vaccine and MMR vaccine. The quantity of egg protein in a dose of MMR vaccine is approximately 40 picograms (much lower than in influenza vaccine, which contains approximately 0.02-1.0 micrograms), and this is believed to be associated with a much lower risk.
Source of the article : Wikipedia
EmoticonEmoticon