Atopy in a Pretoria asthma clinic

Abstract

Introduction.
Atopy in Gauteng and the Free State has been widely studied. However, all these studies reflect the allergy status of individuals living in Johannesburg and Bloemfontein. No study of this nature has been conducted in Pretoria.
Methodology
Standard allergen extracts (Alk Abelló) with negative and positive control were used for testing. The allergen extracts used were: Bermuda grass, 5 grass mix, tree mix, corn culture Zea Mays (pollen), dog hair dander, cat hair dander, standardized mite Dermatophagoides pteronyssinus (HDM), Blatana sp (cockroach), horse, cow’s milk, whole grain, soybean, peanut mix, whole egg, fish mix and wheat. Reactions were measured according to wheal size at 10 minutes, and wheal 3mm greater than the negative control was regarded as a positive reaction for inhalants. The cut-points of Sporok were used for positive food reactions.
Results.
50 asthmatic children were studied. Skin prick test (SPT) positivity was commonest to bermuda grass (24%) while grass mix was the next most common aeroallergen sensitivity. HDM sensitivity occurred in 10% of patients. Food allergens were uncommon but potato sensitivity was displayed in 14%.
Conclusion.
Grass sensitivity reflects the prevailing aero-allergen exposure in a typical highveld city. However it appears that HDM sensitivity is uncommon suggesting that the climate in this area is significantly adverse to mite growth. This may be the first Highveld town where micro-climate does not favour mite survival. Mite studies are required from Pretoria. All children with potato sensitivity had atopic eczema. This requires investigation.