Effects of an acaricide on asthmatic children with house dust mite allergy.

D'Allergen is a recently available acaricidal and allergen reducing agent. To study any beneficial effects of treating houses with this agent in asthmatic children with dust mite allergy, histamine bronchial responsiveness was measured in 18 children before and 6-8 weeks after their homes were treated with the agent. Comparisons were with nine similar asthmatics whose homes were not treated. The mean provocative concentration of histamine causing a 20% fall in forced expiratory volume in 1 s (PC20) increased from 1.02 mg/L to 2.07 mg/L in all 18 children who were studied (1.01 doubling doses). Bronchial responsiveness was relatively unchanged in a well matched control group of nine children studied over comparable time periods (PC20 pre was 1.25 mg/L, PC20 post was 0.67 mg/L). The results suggest that treating homes with D'Allergen reduces bronchial reactivity in asthmatic residents with house dust mite allergy.