House Dust Mite Prevalence in the House of Patients with Atopic Dermatitis in Mashhad, Iran

Background: Being exposed to house dust mites intensifies atopic dermatitis. This study has investigated the contamination rate with Dermatophagoides mites in patient's residential home with atopic dermatitis. Methods: In this cross-sectional study, 40 patients took part with atopic dermatitis (positive or negative for mites by prick Dermal Test). Samples were collected from 3 locations (living room, bedroom and bed) by vacuum cleaner. Dust samples (transferred to freezer -20 ˚C) were examined by direct method and flotation. The data were analyzed using statistical SPSS vr.20 software. Results: Twenty patients of positive prick test included 8 (40%) male and 12 (60%) female. The results of direct observation of mites: 7 cases (35%) in bedding sheets, 6 cases (30%) bedrooms' carpet, 3 cases (15%) living room's carpet. Twenty patients of negative prick test included 8 (40%) male and 12 (60%) female. Only mites were found (5%) in living room's carpets of negative prick test patients. Dermatophagoides pteronyssinus was more frequent than Dermatophagoides farinae. (98% vs 83%). Conclusion: Fifty-five percent of residential homes of prick test positive patients and only 5% of residential homes of prick test negative patients were positive for mite. Sunshine provided home had fewer mites than home where sunshine is not provided. Prick test positive patients used handmade carpets more than machine made ones. In positive prick test patients, mites were found in bed sheet and bedroom’s carpet more than negative prick test patient's sheets and carpets.