International Journal of Dermatology 2008, 47, 790–795 © 2008 The International Society of Dermatology 790 Abstract Background Atopic dermatitis is a common allergic condition in children, often associated with a positive skin reaction to house dust mite allergens. Aim To determine the presence of house dust mites on the skin, clothes, and bedding of patients with atopic dermatitis. Methods Nineteen patients with atopic dermatitis were examined during a 2-year period. Samples from affected and healthy skin surfaces were obtained with adhesive tape, and dust samples from bedding and clothes were collected with a vacuum cleaner at the start of the study and 3–6 weeks later, and examined for the presence of house dust mites. The findings were compared with those of 21 healthy controls. Results The most common mite species on skin were Dermatophagoides pteronyssinus and Dermatophagoides farinae, which were found in nine patients and three controls. The patient group showed a significantly larger percentage of samples with mites than did the control group (34.9% and 7.9%, respectively) (P < 0.001), and a significantly larger percentage of individuals with at least one positive sample (84.2% and 14.2%, respectively) (P < 0.0001). No correlation was found between the number of mites on the skin and clothes/bedding of patients, or between patients and controls with regard to the number of mites on the clothes and bedding. Conclusions Patients with atopic dermatitis showed a higher prevalence of mites on their skin than did healthy individuals, which could be involved in allergic sensitization and disease exacerbation. Blackwell Publishing Ltd Oxford, UK IJD International Journal of Dermatology 0011-9059 1365-4632 © 2008 The International Society of Dermatology XXX Report House dust mites on skin Teplitsky et al. Report House dust mites on skin, clothes, and bedding of atopic dermatitis patients Valery Teplitsky, MD, Kosta Y. Mumcuoglu, PhD, Ilan Babai, MD, Ilan Dalal, MD, Rifka Cohen, BA, and Amir Tanay, MD From the Allergy and Immunology Subunit, Pulmonary Institute, Rabin Medical Center, Petah Tiqwa (affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv), Department of Parasitology, Hebrew University-Hadassah Medical School, Jerusalem, and Allergy and Immunology Unit, Wolfson Medical Center, Holon, Israel Correspondence Kosta Y. Mumcuoglu, PhD Department of Parasitology Hebrew University-Hadassah Medical School PO Box 12272 Jerusalem 91120 Israel E-mail: kostam@cc.huji.ac.il Introduction Atopic dermatitis (AD) is a common form of allergy, affecting more than 20% of children in affluent countries. 1 Its reported prevalence rate in 13–14-year-olds in Israel is 7.8%. 2,3 AD is the first manifestation of the “atopic march,” and a risk factor for the subsequent development of bronchial asthma and allergic rhinitis. Sensitization to house dust mite (HDM) allergens is a high-risk factor for the development of allergic diseases. 4 Its role in AD was first discovered following the observation of both immediate and delayed-type skin reactivity to mite antigens in affected patients, 5,6 and the beneficial effect of the environmental control of mites on the course of the disease. 7,8 In patients with AD, the presence of anti-HDM immuno- globulin E (IgE) frequently coexists with allergic rhinitis and/or bronchial asthma. 1 In these cases, the preferential route of sensitization to HDM probably begins in the upper and lower respiratory tract, after inhalation of HDM allergens. Darsow et al. 9 reported a positive patch test to HDM antigens in 40% of patients with AD. In these patients, sensitization to HDM may involve the transdermal route. To cause transdermal sensitization, HDM allergens must be absorbed through the skin, processed by dendritic cells, and presented to T-helper lymphocytes. For efficient absorption, close and prolonged contact between the skin and HDM allergens is probably necessary, for example, via HDM-contaminated clothes and bedding. Accordingly, several studies have reported that the homes of patients with AD contain large amounts of HDM and their antigens, compared with controls, 10 and that clothes and bedding are an important source of HDM. 11–16 The aim of the present study was to determine the presence of HDM on the skin of patients with AD, and to correlate their numbers with the number of mites found in bedding and clothes. Patients and Methods Patients The study group consisted of 19 children with a diagnosis of AD who were treated at our center from June 2002 to June 2004. The diagnosis of AD was based on the modified criteria of Hanifin and Rajka. 17 Exclusion criteria were as follows: age less than