This guideline advises on the management of patients with egg allergy. Most commonly, egg allergy presents in infancy, with a prevalence of approximately 2% in children and 0.1% in adults. A clear clinical history and the detection of egg white-specific IgE (by skin prick test or serum assay) will confirm the diagnosis in most cases. Egg avoidance advice is the cornerstone of management. Egg allergy often resolves and re-introduction can be achieved at home if reactions have been mild and there is no asthma. Patients with a history of severe reactions or asthma should have reintroduction guided by a specialist. All children with egg allergy should receive measles, mumps and rubella (MMR) vaccination. Influenza and yellow fever vaccines should only be considered in egg-allergic patients under the guidance of an allergy specialist. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for allergists and others with a special interest in allergy. The recommendations are evidence-based but where evidence was lacking consensus was reached by the panel of specialists on the committee. The document encompasses epidemiology, risk factors, diagnosis, treatment, prognosis and co-morbid associations.
The guideline, prepared by an expert group of the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI), addresses the question of diagnosis and treatment as well as recommending guidance for families with egg-allergic children. During the development of these guidelines, all BSACI members were consulted using a web-based system and their comments and suggestions were carefully considered by the SOCC. Evidence for the recommendations was obtained from electronic literature searches of Medline/PubMed, NICE and the Cochrane library (cut off June 2009) using the following strategy and key words – (allergy OR skin prick test OR anaphylaxis OR contraindications OR immediate adverse reactions) AND (egg OR lecithin OR ovalbumin). The experts’ knowledge of the specialist literature and hand searches were used in addition. Where evidence was lacking, a consensus was reached among the experts on the committee. Conflicts of interests were recorded by the BSACI. None jeopardised unbiased guideline development.
- Egg allergy may be defined as an adverse reaction of an immunological nature induced by egg protein. This guideline focuses predominantly on type-1 IgEmediated allergy to egg.
- The prevalence of egg allergy is estimated at approximately 2% in children and 0.1% in adults.
- Egg allergy presents most commonly in infancy, often after the first apparent ingestion with rapid onset of urticaria and angio-oedema; severe reactions involving airway narrowing are uncommon.
- The clinical diagnosis is made by the combination of a typical history of urticaria and/or angio-oedema/vomiting/wheeze with rapid onset (usually within minutes) after ingestion of egg with evidence of sensitization (the presence of specific IgE).
- The reported level of IgE required to support a diagnosis varies between studies. For clinical purposes, an egg white skin prick test (SPT) weal of 5mm or more is considered adequate to confirm a clinical history in most cases of allergy.
- It is not possible to identify a single cut-off value for egg serum-specific IgE, which is ‘diagnostic’ for egg allergy at all ages.
- A food challenge may be necessary to confirm or refute a conflicting history and test results but in practice this is not commonly required.
- No cut-off has been identified for SPT weal size or serum-specific IgE, which predicts the overall clinical severity.
- Egg avoidance advice is the cornerstone of management and may require referral to a dietician if there are multiple food allergies or if the patient is already on a restricted diet for other reasons.
- Mild egg allergy often resolves and an attempt to introduce well-cooked egg as an ingredient (e.g. in cake) may be made at a time-point determined on an individual basis.
- Children with a history of a severe egg reaction are more likely to have persistent disease and should have avoidance and reintroduction guided by a specialist.
- Egg allergy in infancy is associated with an increased risk of developing asthma later in life.
- All children with egg allergy should receive mumps and rubella (MMR) vaccination (only children with a documented history of anaphylaxis to the vaccine itself should have further doses administered under hospital supervision).
- Influenza and yellow fever (YF) vaccines contain measurable quantities of egg protein and if these vaccines are required the patient should be referred to an allergy specialist.
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