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Dust Mite Allergy

Jul 20, 2010; 12:58 PM ET

Dust mite allergy is an allergy to a microscopic organism that lives in the dust found in all dwellings and workplaces. House dust, as well as some house furnishings, contains microscopic mites. Dust mites are perhaps the most common cause of perennial allergic rhinitis. House dust mite allergy usually produces symptoms similar to pollen allergy and also can produce symptoms of asthma.

House dust mites, which live in bedding, upholstered furniture, and carpets, thrive in summer and die in winter. In a warm, humid house, however, they continue to thrive even in the coldest months. The particles seen floating in a shaft of sunlight include dead dust mites and their waste products. These waste products, which are proteins, actually provoke the allergic reaction.

What is house dust?

Rather than a single substance, so-called house dust is a varied mixture of potentially allergenic materials. It may contain fibers from different types of fabrics and materials such as

* Cotton lint, feathers, and other stuffing materials

* Dander from cats, dogs, and other animals

* Bacteria

* Mold and fungus spores (especially in damp areas)

* Food particles

* Bits of plants and insects

* Other allergens peculiar to an individual house or building

Cockroaches are commonly found in crowded cities and in the southern United States. Certain proteins in cockroach feces and saliva also can be found in house dust. These proteins can cause allergic reactions or trigger asthma symptoms in some people, especially children. Cockroach allergens likely play a significant role in causing asthma in many inner-city populations.