SummaryThis 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.

Background: Paracetamol is a common antipyretic/analgesic and a component of many prescription and over- the- counter preparations. Hypersensitivity reactions to paracetamol appear to be increasing, but there are few prevalence data. The mechanism is poorly understood. We identified the clinical features of 32 patients with suspected paracetamol allergy, investigated the underlying mechanism and examined co-existing non-steroidal anti-inflammatory drug (NSAID) tolerance. Methods: Aclinical history was taken and skin tests and an oral challenge were performed in 32 patients with suspected paracetamol allergy. Results: Patients presented with a combination of urticaria, angio-oedema (face, hands), erythema (cutaneous features in 94%), dyspnoea (including laryngeal oedema), rhinoconjunctivitis, cough, abdominal pain and anaphylaxis. Two patients had a positive skin prick test (SPT) and unequivocal history of acute urticaria/facial angio-oedema/conjunctivitis/cough after paracetamol with no other triggers. One patient had a positive intradermal test. Oral challenge was positive in 15 of 31 patients (including self-challenge in 4), triggering (a combination of) rhinitis, conjunctivitis, pruritus, erythema, urticaria, angio-oedema, dyspnoea and abdominal pain. Sensitivity was evident in 1 patient on the basis of the patient’s history. Overall, paracetamol hypersensitivity was confirmed in 16 of the 32 patients (50%). Twelve of the 16 paracetamol-allergic patients (75%)tolerated NSAIDs (negative challenge in 6, negative history in 6). Four of these 16 patients (25%) were intolerant of NSAIDs (positive challenge in 1, self-challenge in 3). Conclusions: In past reports on paracetamol hypersensitivity, only single cases of a positive SPT and detectable specific IgE have been described. Our data confirm that specific IgE may be a mechanism underlying paracetamol hypersensitivity, as in this series 18.8% of the patients had specific IgE. In 81.2% of patients, negative skin tests did not exclude paracetamol hypersensitivity, suggesting that it may be mediated by leukotrienes. However, three quarters of our patients tolerated NSAIDs, implicating an alternative mechanism. In patients with suspected paracetamol allergy, skin tests should be performed in addition to clinical history and oral challenge.

Background: The population of large parts of Africa, South America and travellers to these areas are at risk of yellow fever (YF) with a 50% mortality risk. Yellow fever vaccine (YFV) propagated in hens' eggs confers protection in 95% of the vaccinated. The rate of anaphylaxis for YFV ranges from 0.42 to 1.8/100,000 doses with most cases considered to be due to egg allergy. Egg allergy is a contraindication for the YFV. Nevertheless, the potential fatal sequelae from YF give the incentive to protect everyone at risk irrespective of their allergic status. Methods: Six subjects who had had a recent reaction to egg and who were travelling to endemic areas (3 adults and 3 children) underwent skin prick tests (SPT) with undiluted YFV and egg extract. Intradermal tests for YFV were undertaken at a 1:10 dilution. In 4 egg-allergic patients with a positive SPT to YFV, a 7-step desensitization protocol was used. A 2-step (10 + 90%) protocol was used in the 2 subjects with a negative YFV SPT. Premedication was not administered. Results: All 6 patients were successfully vaccinated. Four patients completed desensitization: 1 developed mild local erythema at the injection site, 1 had fleeting generalized urticaria with local erythema/angioedema and 2 did not experience any adverse reactions. Patients who received YFV in 2 steps developed no adverse reactions. Conclusions: We describe the successful administration of YFV in 6 egg-allergic patients. The Cambridge Allergy 7-step protocol allows for its safe administration in patients with positive SPT to YFV. A 2-step protocol can be used in patients with negative YFV SPT.

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