MITE ALLERGEN (DER-P-1) CONCENTRATION IN HOUSES AND ITS RELATION TO THE PRESENCE AND SEVERITY OF ASTHMA IN A POPULATION OF SYDNEY SCHOOLCHILDREN

House dust mite (HDM) allergen exposure and its relation to HDM allergy and asthma was assessed BE a case-control study conducted over three seasons in 74 Sydney schoolchildren, 33 of whom were allergic to HDM and 12 of whom had current asthma. In each season, histamine inhalation tests and skin prick tests were performed, symptom questionnaires were administered, and dust samples were collected. The mean concentrations of HDM allergen (in micrograms of Der p I PEI. gram of fine dust) were: bed, 38.9 (95% confidence interval [CI] 31.8 to 47.5); bedroom floor; 22.4 (95% CI, 18.3 to 27.5); nod lounge room floor; 13.7 (95% CI, 10.7 to 17.6). The mean of the highest allergen concentration in each house was 51.0 (95% CI, 43.2 to 60.1). All brit two subjects had at least one site in all seasons within HDM allergen concentration greater than 10 mu g/gm, the proposed threshold for asthma symptoms. Subjects with allergy to HDM, symptoms of asthma, or airway hyperresponsiveness did not have higher HDM allergen concentrations in their houses. In this study we were unable to test hypotheses concerning proposed thresholds for risk of sensitization and for risk of asthma symptoms because virtually all subjects were exposed to HDM allergen levels above the proposed thresholds.