Egg sensitization, allergy and component patterns in African children with atopic dermatitis

Area of Science:

• Pediatric Allergy and Immunology
• Dermatology
• Clinical Immunology

Background:

• Egg allergy is a prevalent food allergy in children, particularly those with atopic dermatitis (AD).
• Understanding the prevalence and diagnostic accuracy of egg allergy is crucial in diverse pediatric populations.

Purpose of the Study:

• To determine the prevalence of egg allergy in South African children with AD.
• To evaluate the component patterns and predictive values of various screening tests for egg allergy.
• To compare diagnostic accuracy between different ethnic groups.

Main Methods:

• Prospective, observational study involving children aged 6 months to 10 years with AD.
• Assessment included questionnaires, skin prick tests (SPT) to fresh and commercial egg white, Immuno Solid Phase Allergen Chip (ISAC), ImmunoCAP component tests (including ovomucoid/Gal d 1), and food challenges.
• Participants were recruited from a pediatric university hospital in Cape Town, South Africa.

Main Results:

• A high prevalence of egg sensitization (54%) and confirmed egg allergy (25%) was observed.
• History and standard laboratory screening tests significantly overestimated true egg allergy.
• SPT to fresh egg white demonstrated higher sensitivity and predictive value than commercial extract; ovomucoid was key in differentiating allergy from tolerance.
• Positive predictive values varied by ethnicity, with lower values among Black Africans.

Conclusions:

• Egg allergy prevalence is high in South African children with AD, but clinical history and sensitization markers can overestimate diagnosis.
• SPT using fresh egg white and ovomucoid component testing are valuable tools for accurate diagnosis.
• Population-specific predictive values for diagnostic tests are essential, especially in developing regions.