The effect of frequent vacuum cleaning on the house dust mite allergen, Der p 1 in carpets: a pilot study.

Aim: To determine the effect of frequent vacuum cleaning of carpets on Der p 1, the major group one allergen of the house dust mite Dermatophagoides pteronyssinus.

Methods: Nine rooms and three hallways in the resident medical officers quarters at Wellington Hospital were regularly vacuum cleaned (daily, except weekends) over a five week period. Dust samples were collected before and at weekly intervals for Der p 1 measurement by a double monoclonal antibody ELISA technique.

Results: Der p 1 concentrations progressively declined from an initial geometric mean level (95% CI) of 4.47 micrograms/g fine dust (0.11-21.73) to 1.83 micrograms/g (0.29-9.57) after five weeks, a mean reduction of 48.0% (31.7-65.5). Similarly when expressed per unit area Der p 1 levels declined from 6.35 micrograms/m2 (1.15-35.16) to 1.66 micrograms/m2 (0.33-9.04), a mean reduction of 68.5% (58.6-78.3).

Conclusions: Frequent vacuum cleaning over a short time significantly reduces house dust mite allergen levels in carpets. Larger long term trials are warranted to determine if greater reductions are possible that would be beneficial to house dust mite sensitive individuals.