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Food allergy in South African children with atopic dermatitis
Claudia L Gray1, Michael E Levin, Heather J Zar
1Division of Allergology, Red Cross War Memorial Children's Hospital, Cape Town, South Africa.
Insights
Food allergy is unexpectedly common in South African children with atopic dermatitis (AD), with high rates of sensitization and IgE-mediated food allergy. Peanut allergy prevalence differs significantly between ethnic groups.
Area of Science:
- Immunology
- Pediatrics
- Allergy Research
Background:
- The prevalence of food allergy in South Africa, particularly among Black South Africans, was previously unknown and presumed rare.
- This study addresses the knowledge gap regarding food allergy prevalence and associated risk factors in South African children diagnosed with atopic dermatitis (AD).
Purpose of the Study:
- To determine the prevalence of IgE-mediated food allergy in South African children with atopic dermatitis (AD).
- To identify risk factors associated with food allergy in this pediatric population.
- To explore potential ethnic differences in food allergy prevalence.
Main Methods:
- A prospective, observational study was conducted at a pediatric university hospital in Cape Town.
- Children aged 6 months to 10 years with AD were recruited from a dermatology clinic.
- Assessment involved questionnaires, skin prick tests, Immuno Solid Phase Allergen Chip (ISAC) testing, and incremental food challenges.
Main Results:
- 100 participants (59 Black Africans, 41 mixed race) were enrolled; 66% showed food sensitization and 40% had confirmed food allergy.
- Egg (25%) and peanut (24%) were the most frequent allergies. Black participants had similar sensitization rates but lower overall allergy rates (34% vs. 46%) compared to mixed-race participants.
- Significantly lower peanut allergy rates were observed in Black participants (15%) versus mixed-race participants (37%, p=0.01). Early-onset AD, severe eczema, and younger age (<2 years) were identified as risk factors for food allergy.
Conclusions:
- Food allergy prevalence in South African children with AD is unexpectedly high, comparable to rates in developed countries.
- Ethnic variations exist, notably lower peanut allergy rates in Black South African children compared to those of mixed race.
- Findings highlight the need for further research in unselected South African populations due to potential generalizability limitations.
Background:
The prevalence of food allergy in South Africa is unknown, but previously thought to be rare in black South Africans. This study aimed to determine the prevalence of, and risk factors for, IgE-mediated food allergy in South African children with atopic dermatitis (AD).
Methodology:
This was a prospective, observational study in a paediatric university hospital in Cape Town. Children with AD, aged 6 months to 10 yrs, were randomly recruited from the dermatology clinic. They were assessed for sensitization and allergy by questionnaire, skin prick tests, Immuno Solid Phase Allergen Chip (ISAC) test and incremental food challenges.
Results:
100 participants (59 black Africans and 41 of mixed race) were enrolled, median age 42 months. There were high overall rates of food sensitization (66%) and food allergy (40%). Egg (25%) and peanut (24%) were the most common allergies. Black participants had comparable sensitization (69% vs. 61%) but lower allergy rates (34% vs. 46%) than mixed race participants. This was especially evident for peanut allergy (15% Blacks vs. 37% mixed race allergic to peanut, p = 0.01). Early-onset AD (<6 months), severe eczema, and young age <2 yrs were significant risk factors for food allergy.
Conclusion:
The prevalence of food allergy is unexpectedly high in South African children with AD, and comparable with food allergy rates in patients with AD in developed countries. There are ethnic differences, with significantly lower peanut allergy rates in Blacks compared to mixed race patients. These results are not generalizable to an unselected South African population, which requires further study.
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