The prevalence of atopic dermatitis (AD), an hereditary chronic eczematous skin disease, has risen in populations of industrialized countries over the last 30 years from 3%~5% to 10%~12%. It has been suggested that this increase is in response to provocative factors, such as food allergies and house dust mites (HDM). AD is a multifactorial disorder, frequently associated with other atopic conditions, and the role of HDM allergens as triggering factors has been well documented.

HDM are commonly found in dust of soft furnishings, particularly bedding, in human dwellings. The allergenic glycoproteins of two species of HDM, Dermatophagoides pteronyssinus (European house dust mite )allergen ( Der p 1) and D. farinae (American house dust mite) allergen( Der f 1), are found in the form of faecal pellets of HDM. They become airborne particles during disturbance and their mean size is ≈20 um in diameter. Each particle contains about 0.2 ng of allergen and it is these that trigger human allergies such as eczema, asthma, and some cases of allergic rhinitis. HDM are the dominant indoor allergen associated with atopic symptoms. HDM allergens have been purified and specific immunoassays, such as the enzyme-linked immunosorbent assay (ELISA), have been developed and used in epidemiological studies to quantify HDM allergen exposure to humans.

The detection of HDM allergen in naturally occurring lesions of AD has led to the hypothesis that IgE-mediated allergic contact sensitivity to HDM allergen plays an important part in the pathogenesis of AD. IgE levels are higher in patients with AD than in controls.

Recent evidence strongly suggests that sensitization to allergens is prone to occur in the first 6~12 months of life. Efforts to reduce exposure to HDM allergens can offer quite effective secondary and, perhaps, primary prevention and could provide an alternative candidate in the treatment of AD to topical and/or systemic medicines (which may have associated adverse side-effects ). Reduction of environmental mites produced clinical improvement in AD. In Japan, clean room therapy, which reduces the levels of airborne mites to <3 mites/m2, improved clinical symptoms of patients with AD due to the elimination of HDM faecal pellets. In practice, people suffering from AD do not have access to clinical clean rooms, even for the suggested 11 h a day. A simple, cheap, effective alternative means of reducing HDM exposures is sought.

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