OBJECTIVEThe prevalence of allergic asthma has been rising continually which is correlated with the increasingly closed living environment. House dust mites are the major sources of indoor aeroallergens which induce asthma in sensitized people. To monitor the seasonal variation of house dust mite (HDM)-allergens exposure level in the asthmatic children, which was evaluated to show its correlation with the level of asthma control, HDM allergic sensitization and fraction of exhaled nitric oxide, and to provide basic data for HDM environmental control.

METHODA total of 48 HDM-allergic asthmatic children were enrolled from the asthma clinic in the hospital from March 2011 to January 2012 (boys 34 and girls 14, aging from 3 to 14 years, mean age 8 years and 4 months) in the present study. Dust samples from mattresses, pillows, bedroom floor, living room floor and sofas were collected in each season within one year in the household of all the enrolled patients. The concentrations of Der p 1 and Der f 1 were measured by the enzyme-linked immunosorbent assay (ELISA). To record the Asthma Control Test (ACT) score or Children Asthma Control Test (C-ACT) score for each patient and to collect the data of doctor monitoring asthma control level each time when the patient was clinic visited. The concentration and its classification of the serum specific IgE to HDM was determined by fluoroenzyme-immunometric assay.

RESULTThe average concentration of Der f 1 of all dust samples was significantly higher than that of Der p 1 (0.13 µg/g vs 0.02 µg/g, P < 0.05). The concentrations of Der f 1 from mattresses, pillows and sofas dust samples were significantly higher than those from bedroom floor and living room floor dust samples (0.69 µg/g, 0.42 µg/g and 0.22 µg/g vs 0.07 µg/g and 0.07 µg/g, P < 0.05). The Der f 1 exposure level from mattress dusts in summer but no others was negatively correlated with asthma control level (r = -0.318, P = 0.036). The Der f 1 exposure level from any area dusts in summer and the Der p 1 exposure level from pillows dusts in autumn was negatively correlated with ACT/C-ACT score respectively. The Der f 1 from mattress dusts in winter was positively correlated with classification of sIgE to Der f 1. The Der p 1 exposure level from most areas in each season was positively correlated with classification of sIgE to Der f 1 and Der P 1.

CONCLUSIONDer f 1 was the predominant mite allergen in household dust and mainly came from mattresses, pillows and sofas. The role of the HDM allergen exposure level on the asthma control level and HDM allergic sensitization for the asthmatic children were depended on its area, season and HDM species, which suggested that the future assessment of clinical effect by the HDM environmental control should consider these factors.