What happens when you have an egg allergy

What happens when you have an egg allergy

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 is by double-blind, placebo-controlled food challenges.[2][14] SPT and sIgE own 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.[37] For young children, attempts own been made to identify SPT and sIgE responses strong enough to avoid the need for a confirming oral food challenge.[38]


Mechanisms

Conditions caused by food allergies are classified into three groups according to the mechanism of the allergic response:[28]

  • Non-IgE mediated – characterized by an immune response not involving immunoglobulin E; may happen hours to days after eating, complicating diagnosis
  • IgE-mediated (classic) – the most common type, manifesting acute changes that happen shortly after eating, and may progress to anaphylaxis
  • IgE and non-IgE-mediated – a hybrid of the above two types

Allergic reactions are hyperactive responses of the immune system to generally innocuous substances, such as proteins in the foods we eat.

Why some proteins trigger allergic reactions while others do not is not entirely clear, although in part thought to be due to resistance to digestion. Because of this, intact or largely intact proteins reach the little intestine, which has a large presence of white blood cells involved in immune reactions.[29] The heat of cooking structurally degrades protein molecules, potentially making them less allergenic.[30] The pathophysiology of allergic responses can be divided into two phases. The first is an acute response that occurs immediately after exposure to an allergen.

This phase can either subside or progress into a «late-phase reaction» which can substantially prolong the symptoms of a response, and result in more tissue damage.

In the early stages of acute allergic reaction, lymphocytes previously sensitized to a specific protein or protein part react by quickly producing a specific type of antibody known as secreted IgE (sIgE), which circulates in the blood and binds to IgE-specific receptors on the surface of other kinds of immune cells called mast cells and basophils.

Both of these are involved in the acute inflammatory response.[31] Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators called (cytokines, interleukins, leukotrienes, and prostaglandins) into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth-muscle contraction. This results in runny nose, itchiness, shortness of breath, and potentially anaphylaxis.

Depending on the individual, the allergen, and the mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to specific body systems; asthma is localized to the respiratory system while eczema is localized to the skin.[31]

After the chemical mediators of the acute response subside, late-phase responses can often happen due to the migration of other white blood cells such as neutrophils, lymphocytes, eosinophils, and macrophages to the initial reaction sites. This is generally seen 2–24 hours after the original reaction.[32] Cytokines from mast cells may also frolic a role in the persistence of long-term effects.

Late-phase responses seen in asthma are slightly diverse from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils.[33]

Five major allergenic proteins from the egg of the domestic chicken (Gallus domesticus) own been identified; these are designated Gal d 1-5. Four of these are in egg white: ovomucoid (Gal d 1), ovalbumin (Gal d 2), ovotransferrin (Gal d 3) and lysozyme (Gal d 4).

Of these, ovomucoid is the dominant allergen, and one that is less likely to be outgrown as children get older.[1] Ingestion of under-cooked egg may trigger more severe clinical reactions than well-cooked egg. In egg yolk, alpha-livetin (Gal d 5) is the major allergen, but various vitellins may also trigger a reaction. People allergic to alpha-livetin may experience respiratory symptoms such as rhinitis and/or asthma when exposed to chickens, because the yolk protein is also found in live birds.[1] In addition to IgE-mediated responses, egg allergy can manifest as atopic dermatitis, especially in infants and young children.

Some will display both, so that a kid could react to an oral food challenge with allergic symptoms, followed a day or two later with a flare up of atopic dermatitis and/or gastrointestinal symptoms, including allergic eosinophilic esophagitis.[1][2]

Non-allergic 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.[34][35] Because this mechanism is classified as a pharmacological reaction, or «pseudoallergy»,[34] the condition is considered a food intolerance instead of a true immunoglobulin E (IgE) based allergic reaction.

The response is generally localized, typically in the gastrointestinal tract.[34] Symptoms may include abdominal pain, diarrhea, or any other symptoms typical to histamine release. If sufficiently strong, it can result in an anaphylactoid reaction, which is clinically indistinguishable from true anaphylaxis.[35] Some people with this condition tolerate little quantities of egg whites.[36] They are more often capable to tolerate well-cooked eggs, such as found in cake or dried egg-based pasta, than incompletely cooked eggs, such as fried eggs or meringues, or raw eggs.[36]

Allergic reactions are hyperactive responses of the immune system to generally innocuous substances, such as proteins in the foods we eat.

What happens when you own an egg allergy

Why some proteins trigger allergic reactions while others do not is not entirely clear, although in part thought to be due to resistance to digestion. Because of this, intact or largely intact proteins reach the little intestine, which has a large presence of white blood cells involved in immune reactions.[29] The heat of cooking structurally degrades protein molecules, potentially making them less allergenic.[30] The pathophysiology of allergic responses can be divided into two phases.

The first is an acute response that occurs immediately after exposure to an allergen. This phase can either subside or progress into a «late-phase reaction» which can substantially prolong the symptoms of a response, and result in more tissue damage.

In the early stages of acute allergic reaction, lymphocytes previously sensitized to a specific protein or protein part react by quickly producing a specific type of antibody known as secreted IgE (sIgE), which circulates in the blood and binds to IgE-specific receptors on the surface of other kinds of immune cells called mast cells and basophils.

Both of these are involved in the acute inflammatory response.[31] Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators called (cytokines, interleukins, leukotrienes, and prostaglandins) into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth-muscle contraction. This results in runny nose, itchiness, shortness of breath, and potentially anaphylaxis. Depending on the individual, the allergen, and the mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to specific body systems; asthma is localized to the respiratory system while eczema is localized to the skin.[31]

After the chemical mediators of the acute response subside, late-phase responses can often happen due to the migration of other white blood cells such as neutrophils, lymphocytes, eosinophils, and macrophages to the initial reaction sites.

What happens when you own an egg allergy

This is generally seen 2–24 hours after the original reaction.[32] Cytokines from mast cells may also frolic a role in the persistence of long-term effects. Late-phase responses seen in asthma are slightly diverse from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils.[33]

Five major allergenic proteins from the egg of the domestic chicken (Gallus domesticus) own been identified; these are designated Gal d 1-5. Four of these are in egg white: ovomucoid (Gal d 1), ovalbumin (Gal d 2), ovotransferrin (Gal d 3) and lysozyme (Gal d 4).

Of these, ovomucoid is the dominant allergen, and one that is less likely to be outgrown as children get older.[1] Ingestion of under-cooked egg may trigger more severe clinical reactions than well-cooked egg. In egg yolk, alpha-livetin (Gal d 5) is the major allergen, but various vitellins may also trigger a reaction. People allergic to alpha-livetin may experience respiratory symptoms such as rhinitis and/or asthma when exposed to chickens, because the yolk protein is also found in live birds.[1] In addition to IgE-mediated responses, egg allergy can manifest as atopic dermatitis, especially in infants and young children.

Some will display both, so that a kid could react to an oral food challenge with allergic symptoms, followed a day or two later with a flare up of atopic dermatitis and/or gastrointestinal symptoms, including allergic eosinophilic esophagitis.[1][2]

Non-allergic 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.[34][35] Because this mechanism is classified as a pharmacological reaction, or «pseudoallergy»,[34] the condition is considered a food intolerance instead of a true immunoglobulin E (IgE) based allergic reaction.

The response is generally localized, typically in the gastrointestinal tract.[34] Symptoms may include abdominal pain, diarrhea, or any other symptoms typical to histamine release. If sufficiently strong, it can result in an anaphylactoid reaction, which is clinically indistinguishable from true anaphylaxis.[35] Some people with this condition tolerate little quantities of egg whites.[36] They are more often capable to tolerate well-cooked eggs, such as found in cake or dried egg-based pasta, than incompletely cooked eggs, such as fried eggs or meringues, or raw eggs.[36]


Signs and symptoms

Food allergies generally own a quick onset (from seconds to one hour).

Symptoms may include: rash, hives, itching of mouth, lips, tongue, throat, eyes, skin, or other areas, swelling of lips, tongue, eyelids, or the whole face, difficulty swallowing, runny or congested nose, hoarse voice, wheezing, shortness of breath, diarrhea, abdominal pain, lightheadedness, fainting, nausea, or vomiting.[15] Symptoms of allergies vary from person to person and may vary from incident to incident.[15] Serious harm regarding allergies can start when the respiratory tract or blood circulation is affected. The previous can be indicated by wheezing, a blocked airway and cyanosis, the latter by feeble pulse, pale skin, and fainting.

When these symptoms happen the allergic reaction is called anaphylaxis.[15] Anaphylaxis occurs when IgE antibodies are involved, and areas of the body that are not in direct contact with the food become affected and show severe symptoms.[15][16] Untreated, this can proceed to vasodilation, a low blood pressure situation called anaphylactic shock, and death (very rare).[12][16]

Young children may exhibit dermatitis/eczema on face, scalp and other parts of the body, in older children knees and elbows are more commonly afflicted. Children with dermatitis are at greater than expected risk of also exhibiting asthma and allergic rhinitis.[17]


Treatment

The mainstay of treatment is entire avoidance of egg protein intake.[39] This is complicated because the declaration of the presence of trace amounts of allergens in foods is not mandatory (see regulation of labelling).

Treatment for accidental ingestion of egg products by allergic individuals varies depending on the sensitivity of the person. An antihistamine such as diphenhydramine (Benadryl) may be prescribed. Sometimes prednisone will be prescribed to prevent a possible tardy phase Type I hypersensitivity reaction.[40] Severe allergic reactions (anaphalaxis) may require treatment with an epinephrine pen, i.e., an injection device designed to be used by a non-healthcare professional when emergency treatment is warranted.

A second dose is needed in 16-35% of episodes.[41]

Immunotherapy

There is athletic research on trying oral immunotherapy (OIT) to desensitize people to egg allergens. A Cochrane Review 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. They concluded there was a need for standardized protocols and guidelines prior to incorporating OIT into clinical practice.[42] A second review noted that allergic reactions, up to anaphylaxis, can happen during OIT, and recommends this treatment not be routine medical practice.[43] 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 reactions, and the authors came below on the side of not recommending this as treatment.[44]

Avoiding eggs

Prevention of egg-allergic reactions means avoiding eggs and egg-containing foods. People with an allergy to chicken eggs may also be allergic to other types of eggs, such as goose, duck, or turkey eggs.[1] 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 substitutes can substitute for specific functions (potato starch and tapioca for water binding, whey protein for aeration or particle binding, or soy lecithin or avocado for emulsification). Food companies produce egg-free mayonnaise and other replacement foods.

What happens when you own an egg allergy

Alfred Bird invented egg-free Bird’s Custard, the original version of what is known generically as custard powder today.[45]

Most people discover it necessary to strictly avoid any item containing eggs, including:[13]

  1. Ovoglobulin (egg white protein)
  2. Ovovitelia (egg yolk protein)
  3. Meringue or meringue powder
  4. Lysozyme (egg white protein)
  5. Silici albuminate
  6. Ovalbumin (egg white protein)
  7. Ovovitellin (egg yolk protein)
  8. Ovotransferrin (egg white protein)
  9. Egg wash
  10. Apovitellin (egg yolk protein)
  11. Ovomucin (egg white protein)
  12. Egg Beaters (cholesterol-free, uses egg whites)
  13. Simplesse
  14. Dried egg solids, powdered egg
  15. Livetin (egg yolk protein)
  16. Fat substitutes (some)
  17. Eggnog
  18. Mayonnaise
  19. Albumin (egg white protein)
  20. Egg, egg white, egg yolk
  21. Ovomucoid (egg white protein)
  22. Vitellin (egg yolk protein)

Ingredients that sometimes include egg protein include: artificial flavoring, natural flavoring, lecithin and nougat candy.

Probiotic products own been tested, and some found to contain milk and egg proteins which were not always indicated on the labels.[46]


Causes

Vaccines

Influenza vaccines are created by injecting a live virus into fertilized chicken eggs.[18] The viruses are harvested, killed and purified, but a residual quantity of egg white protein remains. Each year, vaccines are created to provide protection against the flu viruses expected to be prevalent in the upcoming freezing weather months.[18] For the 2017-2018 flu season, the vaccines are described as IIV3 and IIV4 for resistance to the expected three or four viruses.

For adults ages 18 and older there is also an option to get recombinant flu vaccines (RIV3 or RIV4) which are grown on mammalian cell cultures instead of in eggs, and so are no risk for people with severe egg allergy.[19] Recommendations are that for people with a history of mild egg allergy should get any IIV or RIV vaccine. People with a more severe allergic reaction may also get any IIV or RIV, but in an inpatient or outpatient medical setting, istered by a healthcare provider.

What happens when you own an egg allergy

People with a known severe allergic reaction to influenza vaccine (which could be egg protein or the gelatin or the neomycin components of the vaccine) should not get a flu vaccine.[19]

Each year the American Academy of Pediatrics (AAP) publishes recommendations for prevention and control of influenza in children.[20][21][22] In the most recent guidelines, for 2016-2017, a change was made, that children with a history of egg allergy may get the IIV3 or IIV4 vaccine without special precautions. It does, however, state that «Standard vaccination practice should include the ability to reply to acute hypersensitivity reactions.»[20] Prior to this, AAP recommended precautions based on egg allergy history: if no history, immunize; if a history of mild reaction, i.e., hives, immunize in a medical setting with healthcare professionals and resuscitative equipment available; if a history of severe reactions, refer to an allergist.[21][22]

The measles and mumps parts of the «MMR vaccine» (for measles, mumps, and rubella) are cultured on chick embryo cell culture and contain trace amounts of egg protein.

The quantity of egg protein is lower than in influenza vaccines and the risk of an allergic reaction is much lower.[23] One guideline stated that every infants and children should get the two MMR vaccinations, mentioning that «Studies on large numbers of egg-allergic children show there is no increased risk of severe allergic reactions to the vaccines.»[24] Another guideline recommended that if a kid has a known medical history of severe anaphylaxis reaction to eggs, then the vaccination should be done in a hospital middle, and the kid be kept for observation for 60 minutes before being allowed to leave.[23] The second guideline also stated that if there was a severe reaction to the first vaccination — which could own been to egg protein or the gelatin and neomycin components of the vaccine — the second is contraindicated.[23]

Eating egg

The cause is typically the eating of eggs or foods that contain eggs.

Briefly, the immune system over-reacts to proteins found in eggs. This allergic reaction may be triggered by little amounts of egg, even egg incorporated into cooked foods, such as cake. People with an allergy to chicken eggs may also be reactive to goose, duck, or turkey eggs.[1]

Exercise

There is a condition called food-dependent, exercise-induced anaphylaxis (FDEIAn). Exercise can trigger hives and more severe symptoms of an allergic reaction. For some people with this condition, exercise alone is not sufficient, nor consumption of a food to which they are mildly allergic sufficient, but when the food in question is consumed within a few hours before high intensity exercise, the result can be anaphylaxis.

What happens when you own an egg allergy

Egg are specifically mentioned as a causative food.[25][26][27] One theory is that exercise is stimulating the release of mediators such as histamine from IgE-activated mast cells.[27] Two of the reviews postulate that exercise is not essential for the development of symptoms, but rather that it is one of several augmentation factors, citing evidence that the culprit food in combination with alcohol or aspirin will result in a respiratory anaphylactic reaction.[25][27]


Prognosis

The majority of children outgrow egg allergy. One review reported that 70% of children will outgrow this allergy by 16 years.[14] In subsequently published longitudinal studies, one reported that for 140 infants who had challenge-confirmed egg allergy, 44% had resolved by two years.[47] A second reported that for 203 infants with confirmed IgE-mediated egg allergy, 45% resolved by two years of age, 66% by four years, and 71% by six years.[48] Children will be capable to tolerate eggs as an ingredient in baked goods and well-cooked eggs sooner than under-cooked eggs.[14] Resolution was more likely if baseline serum IgE was lower, and if the baseline symptoms did not include anaphylaxis.[14][48]


Prevention

When eggs are introduced to a baby’s diet is thought to affect risk of developing allergy, but there are contradictory recommendations.

A 2016 review acknowledged that introducing peanuts early appears to own a benefit, but stated «The effect of early introduction of egg on egg allergy are controversial.»[9] A meta-analysis published the same year supported the theory that early introduction of eggs into an infant’s diet lowers risk,[8] and a review of allergens in general stated that introducing solid foods at 4–6 months may result in the lowest subsequent allergy risk.[10] 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.[11]


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