Rural and Urban Food Allergy Prevalence from the South African Food Allergy Study (Saffa)

Publication date: Available online 7 August 2018

Source: Journal of Allergy and Clinical Immunology

Author(s): Maresa Botha, Wisdom Basera, Heidi E. Facey-Thomas, Ben Gaunt, Claudia L. Gray, Jordache Ramjith, Alexandra Watkins, Michael E. Levin

Abstract

Background

Food sensitization and challenge proven food allergy has not been compared in urban and rural settings.

Objective

To determine and compare the prevalence of food sensitization and challenge-proven IgE-mediated food allergy in urban and rural South African toddlers aged 12-36 months.

Methods

This cross-sectional study of unselected children included 1185 participants in urban Cape Town and 398 in the rural Eastern Cape. All participants completed a questionnaire and underwent skin prick tests to egg, peanut, cow's milk, fish, soya, wheat, and hazelnut. Participants with SPT≥ 1mm to one or more foods and not tolerant on history underwent an open oral food challenge.

Result

The prevalence of food allergy was 2.5% (CI 1.6-3.3) in urban children - most commonly to raw egg white (1.9%), followed by cooked egg (0.8%), peanut (0.8%), cow's milk (0.1%) and fish (0.1%). Urban sensitization (≥1mm SPT) to any food was 11.4% (CI 9.6%-13.3%) and 9.0% (CI 7.5%-10.8%) at ≥3mm SPT. Sensitization in the rural cohorts was significantly lower than the urban cohort (1mm SPT 4.5%, CI 2.5-6.6; 3mm SPT 2.8%, CI 1.4-4.9: p<0.01).

In the rural black African cohort 0.5% (CI 0.1%-1.8%) of children were food allergic - all to egg. This is significantly lower than the prevalence of urban cohort overall (2.5%) and urban black African participants (2.9%; CI 1.5%-4.3%)(p=0.006).

Conclusion

Food allergy prevalence in Cape Town is comparable to rates in industrialised middle-income countries and is significantly higher than in rural areas. Further analysis will describe and compare environmental exposures and other risk factors in this cohort.

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