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Year-round housedust mite levels on the Highveld
A Cadman1, R Prescott, P C Potter
1Bernard Price Institute, University of the Witwatersrand, Johannesburg.
Summary
House-dust mite (HDM) allergen levels were measured in homes. Many homes exceeded safe levels, indicating a year-round risk for respiratory allergies, even at previously considered safe mite concentrations.
Area of Science:
- Allergen research
- Environmental microbiology
- Public health
Background:
- House-dust mites (HDM) are a common source of indoor allergens.
- Dermatophagoides pteronyssinus is a primary species responsible for HDM allergies.
- Understanding HDM allergen levels is crucial for managing respiratory conditions.
Purpose of the Study:
- To quantify DerPI allergen levels from Dermatophagoides pteronyssinus in suburban homes.
- To assess the prevalence of HDM infestation exceeding established safety thresholds.
Main Methods:
- A longitudinal study spanning four seasons (1994/95) was conducted.
- Mattress and carpet dust samples were collected from 30 randomly selected suburban homes.
- Homes were chosen based on similar socio-economic and environmental conditions.
Main Results:
- All sampled homes contained HDM allergen DerPI.
- 20% of homes had HDM levels above the 2 µg/g dust threshold considered safe for respiratory health.
- HDM infestation persisted for months once established, with significant, unexplained seasonal variations observed.
Conclusions:
- HDM populations are highly sensitive to microclimatic changes.
- The year-round presence of HDM on the Highveld poses a significant public health concern.
- Allergen levels below 2 µg/g dust may still trigger allergic symptoms, necessitating a re-evaluation of safe thresholds.