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Higher food allergy rates in urban children than in their rural counterparts

Published online: August 7, 2018

Chronic conditions such as allergies are a growing public health concern, especially in children. Although previous studies have shown differences in the rates of asthma, allergic rhinitis and eczema between urban and rural communities, little was known about whether food allergy rates also differ in urban and rural settings.

In this study published in The Journal of Allergy and Clinical Immunology (JACI), Botha et al screened more than 2000 toddlers living either in urban Cape Town or in a deeply rural area in the Eastern Cape Province for food sensitisation by doing skin prick tests for the commonest food allergens in children. Children who had a reactive skin prick test result and who were not clearly tolerating a particular food in their regular diet underwent an oral food challenge to confirm or refute a food allergy diagnosis.

The authors found that 2.5% of the children in the urban setting had a confirmed food allergy. The most common allergy was to egg (1.8%), with some children being allergic to peanut (0.8%) and very few to milk and fish (0.1%). There were no differences in food allergy rates between urban children of different ethnicities. In the rural study site comprising solely Black African participants, only 0.5% of children had a food allergy.

This first population-based comparative study of food allergies in an urban setting and a deeply rural pre-industrialised community practicing subsistence farming showed marked differences in food allergy prevalence.  The fact there is no association with ethnicity in the urban cohort indicates that ethnicity is not the factor accounting for the urban-rural difference; rather there may be other environmental factors in rural settings that protect against food sensitisation and food allergy.   

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

Rural and urban food allergy prevalence from the South African Food Allergy Study (SAFFA)