Duck egg tolerance amongst paediatric patients with known hen egg allergy-'it's no yolk'

Abstract

Background: IgE mediated allergy to hen egg affects nearly 1:10 Australian infants, with an established trend towards escalating numbers of new diagnoses and persistent allergies. Without robust evidence to support efficacy and safety of immunotherapy, hen egg avoidance remains the gold standard of treatment, an approach which places significant burden on the patient and his/her caregivers. Method: This prospective observational pilot study was designed to understand whether paediatric patients with a known hen egg allergy are tolerant of duck egg. Skin prick testing (SPT) to duck egg was performed in all recruited hen egg allergic subjects aged 6 months to 18 years. All subjects were invited, with a small cohort consenting, to participate in open oral food challenges (OFC) to duck and hen egg. Continued home consumption and tolerance was assessed in all subjects with a negative result at the supervised duck egg OFC, using caregivercompleted questionnaires issued one week, four weeks, and twelve weeks post challenge. Results: Of the 149 study subjects, 73.2% (n=109 subjects) had a positive skin prick test to fresh duck egg. 59.0% (n= 13) of the 22 OFC subjects had no clinical reaction to duck egg, however two had delayed symptom onset at home and 54.0% (six of the remaining 11 subjects) proved tolerant to the subsequent hen egg oral challenge. Absence of eczema was the only significant predictor of a successful duck egg challenge amongst hen egg allergic subjects. Conclusion: Duck egg co-sensitisation is common amongst paediatric patients with a hen egg allergy. However, further research is required to identify predictors of tolerance, given SPT results were poorly correlated with OFC outcomes in this study. Importantly, for a subset of hen egg allergic infants, children, and adolescents, duck egg appears to be a safe, nutritious, and acceptable alternative.L6317768882020-05-25 <br />