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Year-round housedust mite levels on the highveld


A Cadman
R Prescott
PC Potter

Abstract

Objective. To determine the levels of the allergen DerPl, attnbutable to the house-dust mite (HDM) Dermatophagoides pteronyssinus.
Design. A four-season study conducted during 1994/95, sampling mattresses and carpets in the main bedrooms of suburban homes.
Setting. Thirty randomly selected homes in the Edenvale area, occupied by both black and white families living under similar socio-economic conditions in comparable environments.
Results, All homes tested positive for the allergen, and in 20% HDM levels exceeded levels recognised as 'safe' in terms of respiratory allergy, i.e. 2 ug/g of dust. Once mites were established in a home, they remained for months thereafter. The considerable seasonal variation recorded in HDM levels could not readily be explained.
Conclusion. The HDM is extremely sensitive to minimal variations in microclimate. Its year-round presence is of concern on the Highveld. Infestation levels below 2 JIg/g of dust, until recently considered the critical point for sensitisation, may be significant triggers of symptoms.


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eISSN: 2078-5135
print ISSN: 0256-9574