Nutrition and Eggs
Egg allergy in infants and children
Eggs allergy in infants and children
The frequency of all food hypersensitivity peaks in the first year of life and represents a serious health issue. Milk and egg are the two most common food allergens.1
Many estimates of prevalence of food allergies are based on self-reported data and therefore may overstate the issue. However, a 2007 meta-analysis that included both self-reported and more objective evidence of IgE-mediated reactions, such as skin prick and double-blind challenge data, suggested that food allergy affects about 4% of children.2 The reported prevalence for egg allergy in young children based on symptomatic and skin prick/IgE tests in this analysis was 0.5% - 2.5%.
Egg allergy is most common in infants under the age of twelve months, but tends to resolve with time in most children by late childhood. The phenomenon of tolerance among children with food allergies is well-recognised. Therefore, although some food allergies, such as peanut allergy, persist into adult life, egg allergy frequently diminishes and disappears after a period of time. Estimates of persistence vary, but evidence suggests that by 10 years of age more than one third of children will have developed tolerance to egg and that at least two thirds of children will have outgrown their allergy by 16 years of age.3 Those with other allergies or with a family history of allergy seem to be particularly vulnerable to persistent egg allergy.
Food allergy commonly presents in infants as atopic dermatitis (atopic eczema) and egg allergy is the most common food to cause eczema in babies. The presentation of an egg allergy in sensitised babies can be dramatic. The most common immediate way in which this allergy presents is with a red rash around the mouth within seconds of eating a meal containing egg, followed in a few minutes by angioedema - swelling around the mouth, on the face and also inside the mouth. Rapid onset of vomiting is also common. However, particularly in patients with non-IgE mediated reactions to egg, the symptoms may be delayed for many hours with slowly worsening eczema, abdominal pain and distension, diarrhoea and occasional constipation. Frequently, as they get older, children will also display respiratory symptoms such as sneezing, wheezing and asthma. Anaphylaxis may also occur, but is rarer than in milk or nut allergy.
It has been observed that more than half of the infants who develop egg allergy begin to have symptoms within minutes of ingesting egg for the first time. In infants with eczema, sensitisation can occur just through skin contact with very small amounts of egg. While it is possible that some may have unknowingly been exposed to and sensitised by small amounts of egg, for example, in a manufactured baby food, some may have been sensitised before birth or via breast milk. However, there is no evidence that the avoidance of egg during pregnancy or lactation, or delayed introduction at weaning, will reduce the incidence of egg allergy. In fact there is evidence that infants whose mothers were exposed to higher levels of egg in pregnancy showed less egg allergic responses at 6 months than those whose mothers had minimal exposure to egg during pregnancy.4 Therefore, the avoidance of egg in pregnancy is not the best strategy, and pregnant women should be advised to eat a balanced diet without specifically avoiding allergens such as egg.
The current recommended weaning advice from the Department of Health is to commence the introduction of solid foods at around 6 months of age.5 It is important that a wide range of foods are introduced at or by six months and in the majority of children, provided that there has been no evidence of eczema or other symptoms of egg allergy as discussed above, there is no need to exclude potentially allergenic foods, such as eggs. Delayed introduction of such foods may indeed be counter-productive and more likely to be associated with subsequent development of allergies.6 Therefore pregnant mums are advised to follow a varied, balanced diet that includes as wide a range of foods as possible, including eggs.7
Diagnosis of egg allergy, as with other food allergies, requires confirmation by the presence of antigen-specific IgE, using skin prick tests and immunoassay of serum antigen-specific IgE concentration.1 Treatment involves the removal of all sources of egg, with subsequent periodic reviews of the child’s allergic status to assess evidence of developing tolerance. When there is evidence of a diminishing skin test reaction or levels of circulating egg specific IgE, challenge with egg protein would be attempted under controlled medical conditions, initially using baked egg and ultimately with raw egg. Subject to the results of such challenges, in most children eggs would be gradually re-introduced at some time in later childhood, initially as small amounts in baked goods. However, in small proportion of people, the egg allergy will persist into adult life.
In patients with suspected non-IgE mediated reaction to egg there is currently no reliable test to confirm the diagnosis. Thus a trial of an egg free diet followed by controlled challenge is the only strategy for management.
1 Longo G, Berti I, Burks AW et al (2013) IgE-mediated food allergy in children. Lancet. 2013 Jul 8. pii: S0140-6736(13)60309-8. doi: 10.1016/S0140-6736(13)60309-8
2 Rona RJ, Keil T, Summers C et al (2007) The prevalence of food allergy: a meta-analysis. Journal of Allergy and Clinical Immunology, 120:638-46
3 Savage JH, Matsui EC, Skripak JM et al (2007) The natural history of egg allergy. Journal of Allergy and Clinical Immunology, 120:1413-7
4 Vance GHS, Grimshaw KEC, Briggs R et al (2004) Serum ovalbumin-specific immunoglobulin G responses during pregnancy reflect maternal intake of dietary egg and relate to the development of allergy in early infancy. Clinical & Experimental Allergy 34: 1855-61
6 Koplin JJ, Osbourne NJ, Wake M et al (2010) Can early introduction of egg prevent egg allergy in infants? Journal of Allergy and Clinical Immunology, 126: 807-13