Common. Associated with eczema. Can be prevented by early introduction as part of weaning – see EAT study, where 75% of cases prevented where families could stick to protocol.
Mostly mild reaction, 7% anaphylaxis quoted before diagnosis made. Moderate to severe reactions can occur just from contact, if raw egg has been applied to inflamed nappy rash.
Diagnosis is made clinically. No investigations are required if reactions mild (not really defined!). Testing “useful” in “mod-severe” reactions (not specified really but does say hospital challenge if “severe vomiting or diarrhoea”). No cut off given for SPT or IgE although historically 95% PPV at 4mm or 4ku/l under age 2, 7mm or 7ku/l over the age of 2.
Encourage early introduction of peanut (do peanut test at the same time, if you are going to test), as per EAT study.
Children referred to dieticians have half the rate of accidental reactions! Referral to dietician if multiple food allergies, or nutritional concerns, or difficulty following ladder; or if severe allergy.
1/3 of children grow out of their egg allergy by age 3, 2/3 by age 6. Predictors of tolerance are ability to have baked egg, mild reactions only, isolated egg allergy, IgE level (and presumably SPT but not mentioned).
Predicting tolerance of cooked egg tricky – Gal d1 (ovomucoid component – heat stable) >=11 indicated high risk of reacting to cooked or raw [NOT baked?]. Also linked to persistence of egg allergy. In 1 study, helps predict tolerance of boiled egg, whereas Gal d2 (ovalbumin – heat labile) predicts tolerance of raw egg. If isolated Gal d2 positive then likely transient. Better predictive value than regular IgE for egg anaphylaxis. Can be useful for assessment of resolution in adults.
Ovomucoid sIgE ≤1.2 kUA/L considered safe for home introduction.
In study of raw egg tolerance at age 5+, ovalbumin IgE/total IgE ratio was best predictor.
Since most children do grow out of this allergy, step by step, cautious reintroduction should be encouraged from 12 months of age, or 6 months after the last reaction. This can be safely done at home unless:
- history of severe reaction
- severe or poorly controlled asthma
Mild asthma, and reaction to trace amount (or contact only) are relative indications.
For severe allergy, or allergy beyond age 6-7yrs, check history of reactions and repeat tests – but no specific IgE levels to indicate when to challenge! “Reasonable” if no recent reaction and reduction in IgE or SPT.
Egg “ladder” for step by step reintroduction simply baked egg (eg sponge cake), followed by less well cooked egg (French toast), followed by raw or nearly raw (mayonnaise).
Where stage 1 achieved but difficultly moving further, regular ingestion should promote tolerance.
Although can be frightening to challenge at home, prolonged total exclusion more likely to lead to persistent allergy, and of course increases dietary plus social exclusion.
If there is a reaction at any stage, the previously tolerated diet should be continued and further escalation considered after 3-6 months.
Taste can be an issue – try egg fried rice, or sweet muffin, egg noodles, Quorn, sponge fingers, egg custard.
Remember vaccines – MMR made using egg but no identifiable egg protein remains so egg allergy not given as possible contraindication. Out of the scheduled vaccines, only influenza vaccines is a potential issue, and even then nasal flu vaccine (or low egg or egg free injectable version) can be given with standard precautions unless anaphylaxis to egg requiring intensive care. Just specialist travel vaccines eg Yellow fever that might be an issue. For latter, should be “referred to specialist with access to designated YF vaccination centre” (3 in Lanarkshire, including Monklands hospital travel clinic and Calderlea centre at Alison Lea!). No mention of JE, TBE??
[BSACI guidance 2021]
Egg allergy in adulthood has significant impact on quality of life, particularly around dietary restrictions and emotional impact. “Bird-egg syndrome” is allergy to both egg, feathers and chicken, due to Gal d5 (alpha livetin) sensitisation – can develop in adulthood, usually where exposed to feathers.
Treatment
No standard immunotherapy regime for egg. EAACI do not recommend OIT for persistent egg allergy.
One regimen is with raw egg white powder (!), aiming for target maintenance dose of 1g of egg white protein (approximately 1/3rd of an egg white). If no success, switch to cooked egg and try again. 3 months after reaching target dose, oral egg challenge with half a boiled egg white – if passed, allow up to one-half of an egg in heated form, but do not increase amount of raw egg. Aim for continuous daily consumption and add well cooked egg (eg meatballs, egg pasta, brioche bread, pancakes, pastries) into the diet.
Cochrane review 2018 (10 RCTs, ages 1-18), 82% achieved 10g egg protein (1 egg) cf 10% of control. 50% achieved sustained unresponsiveness by the fourth year. Small studies, low quality evidence.
In 2021 Helsinki study, after 8 months of OIT, 44% of the children were desensitized, 46% partially desensitized; at 18 months, over 80% eating egg regularly, 72% able to eat target dose. More than half not restricting at all.
Early discontinuation is associated with underlying asthma, higher specific IgE and lower threshold during challenge.
Ovomucoid (Gal d1) IgE 8.85 kU/L indicated a 95% probability of early discontinuation or ongoing reactions over time. Ovalbumin (Gal d2) is heat labile so if this is the only one you are sensitised to, you should be ok with baked.
Low pre-treatment levels of egg white and ovomucoid IgE predict sustained unresponsiveness following egg immunotherapy. Decrease in size of SPT and increase in egg-specific IgG4 over time predicts tolerance in children being treated with egg OIT. Ovalbumin IgG4 and Ovalbumin IgE/IgG4 ratio may be useful to predict the development of tolerance to egg in oral immunotherapy.
High egg IgE levels and sensitization to all four components (Gal d 1-4) predicted failure or impaired response, but Helsinki authors still felt OIT worth trying.
Another way would be to start with egg yolk (carefully separated and the sac disposed of, since it has been in contact with the white) – discussed in a Japanese paper looking at a single adult female – or even quail egg followed by duck egg (TIP style programme).
