Introduction to dust mites

There are two species of house dust mites found in North America. These mites are so small they are virtually invisible without magnification. A typical house dust mite measures 420 micrometers in length and 250–320 micrometres (0.0098–0.013 in) in width. Female mites lay cream-colored eggs coated with a sticky substance so eggs will cling to the substrate. These mites have two distinct immature stages. Under optimal conditions, the entire life cycle from egg to adult takes three-four weeks.

House dust mites feed on human skin scales, pollen, fungi, bacteria and animal dander. Dust mites do not drink free water, but absorb water from the air and the environment. To thrive, dust mites need very warm temperatures (75-80 degrees F) and high humidity levels.

Humans continually shed skin and lose about 1/5 ounce of dead skin each week. We also spend about one-third of our lives sleeping so high levels of dust mites are often associated with the bedroom, especially bedding and the mattress. Dust mites also eat animal dander so allergens will be plentiful in areas where family pets sleep.

Asthma and allergies

Allergens produced by house dust mites are among the most common triggers of asthma. Some main signs of house dust mite allergies are itchiness, sneezing, inflamed or infected eczema, watering eyes, reddening eyes, runny nose and clogging in the lungs.

Dust mite allergy is an immune system reaction to a certain dust mite protein. This reaction triggers inflammation in the lining of the nasal passages (allergic rhinitis), causing sneezing, runny nose and other signs and symptoms associated with hay fever.

For some people, dust mite allergy may be the primary cause of inflammation and contraction of airways of the lungs (asthma), resulting in wheezing, shortness of breath and other breathing difficulties.