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Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Indoor allergens facts
• What are allergens?
• What actually is house dust?
• What are dust mites?
• What conditions are most favorable to dust mites?
• How do dust mites cause allergic symptoms?
• Can cockroaches cause allergic symptoms?
• What about allergies to molds?
• What about allergies to pets?
• What about allergies to indoor pollens and houseplants?
• Find a local Asthma & Allergy Specialist in your town
• Indoor Allergens Index

The digestive enzymes that are discharged into the mite feces are the most bothersome of the dust-mite allergens. Less potent allergens are found in the mite bodies. The mite's tiny fecal pellets disintegrate to form a very fine powder that can easily float into the air when disturbed. This commonly occurs during vacuuming, making the bed, turning in bed while sleeping, or walking on the carpet. When an allergic person inhales these particles, asthma or nasal allergy symptoms may occur. There is also evidence that allergic eczema can be aggravated by this exposure.

• Each dust mite lives for approximately 30 days and produces about 20 fecal pellets per day. During that time, females may have added 30 new dust mites to the population.
• About 10% of the population is allergic to dust mites. About 80% of asthmatic children are allergic to dust mites.

Over the past decades, cockroaches have become recognized as a powerful indoor allergen. Cockroach allergy can be a major factor in serious asthma and nasal allergy. Cockroaches tend to be very troublesome in inner-city areas, multifamily dwellings, and around areas of food preparation.

Cockroaches are among the oldest of all living species (about 350 million years old). The three species of cockroaches that are commonly found in the United States are Blatella germania (German), Periploneta americana (American), and Blatella orientalis (Oriental). (The genus name for the American cockroach, periploneta, is derived from the Greek word, planetes, which means wanderer.)

Cockroaches are hardy, adaptable creatures that thrive in areas where food and water supplies are plentiful. They may be found around dripping faucets and kitchen areas. They do stray, however, to other areas and can commonly be found in children's bedrooms where food is often eaten. The major cockroach allergens are found in their digestive enzymes, saliva, and body parts. As is the case with dust-mite allergens, these microscopic particles become airborne when disturbed by motion in the room.