Mite elimination--clinical effect on eczema.

Allergic reactivity to house-dust mites (HDM) can be detected in patients with atopic eczema by prick and patch test challenge. To determine the clinical relevance of this reactivity, we performed a placebo-controlled, double-blind trial of anti-HDM measures. Active treatment comprised Gortex bags for all the bedding elements, a high-powered vacuum cleaner, and a spray containing benzyl alcohol and tannic acid to kill mites and denature allergens. Placebo treatment was light cotton bags, a cheap vacuum cleaner, and water spray. Forty-eight patients (28 active group) completed the trial, which lasted 6 months. Dust was sampled from the mattress surface and bedroom and living-room carpets before and at monthly intervals after institution of the measures. Dust was weighed and Der p 1 determined by ELISA (ALK). Patients were assessed for area and severity of eczema by a blinded observer. There was a highly significant reduction in bed surface dust - most beds yielded insufficient dust to extract and assay. Carpet Der p 1 levels were reduced to similar minimal levels by both active and placebo treatments (about 250 ng/m2). There were highly significant benefits on the eczema scores, the active treatment being greatly superior to placebo (P< or =0.0006; analysis of covariance). In conclusion, Gortex bed bags were highly effective at containing dust within the bed. This was associated with clinical improvement in most patients with atopic eczema - the biggest improvements were seen in the most severely affected subjects.