An allergy, or hypersensitivity reaction, occurs when the body's immune system overreacts to a substance that is normally harmless (allergen), such as mold, pollen, animal dander or dust mites.
The white blood cells of an allergic individual produce an antibody called immunoglobulin E (IgE), which attaches to the allergen. This triggers the release of histamine and other inflammatory chemicals that cause allergic symptoms, such as runny nose, watery eyes and hives.
Dust mites (Dermatophagoides farinae) are one of the most common indoor allergies. The mites are microscopic insects that are in the same biological family as spiders. Individuals may be allergic to chitin, a major component of the dust mite body and/or their digestive enzyme called DerP1, which is present in dust mite feces and decayed carcasses. Dead dust mites and their feces mix with dust and become airborne. When people who are allergic to dust mites inhale the dead dust mites and their byproducts, symptoms such as sneezing, runny nose and water eyes may result.
The average male dust mite lives an average of 20 to 30 days. A mated female can live up to 10 weeks, laying 60 to 100 eggs during the last five weeks of her life. In 10 weeks, a single dust mite produces about 2,000 fecal particles.
Unlike pollen, dust mites are present year-round in nearly every bedroom and home. While dust mites thrive in warm, humid environments like bedding, fabric, carpet furnishing and clothing, they are also found in dry or cold climates. Dust mites are able to survive and reproduce easily in bedding (especially in pillows) because of the humidity generated by the human body during breathing and perspiring.
The average person sheds about 1.5 grams of skin cells every day (about 0.3-0.45 kg per year), which is enough to feed roughly one million dust mites under ideal conditions.
Most dust mite allergies are mild and do not require treatment. Minimizing exposure to dust by regularly washing linens and fabric in hot water, vacuuming carpets and washing floors can help prevent reactions. However, individuals who experience frequent allergies may benefit from allergy medications, such as antihistamines, nasal sprays, decongestants and allergen immunotherapy (allergy shots).
Dust mite allergies are most common among children, but they can develop at any age. Some people outgrow their allergies as they age.
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