Common Cause of Household Allergies - A Household Allergen Often Overlooked

There are many substances in the household that can cause allergies in humans, including animal dander, insect parts, mold spores and pollen. The most common allergens found in the home, however, are from dust mites.

These are tiny creatures related to ticks, chiggers, and spiders that live in close association with humans. Their primary food is dander (skin scales) shed from human and pet activity. Moisture from the body, which is most prevalent in sheets and bedding, makes an ideal breeding ground. Most homes in the United States probably have detectable levels of dust mites and their allergy-producing fragments.

Dust mites are not parasitic nor are they capable of biting or stinging humans. Their significance as pests is due to powerful allergens contained in the mites, their cast skins, fecal material and secretions. Symptoms of a dust mite allergy include stuffy or runny nose, sneezing, coughing and watery eyes. Inhalations of dust mite allergens by hypersensitive individuals can result in acute attacks of bronchial asthma, accompanied by wheezing, shortness of breath, and perhaps even death. They have also been identified as a leading cause of eczema, a skin condition. Diagnostic tests and clinical studies by allergist have shown dust mite allergies to be the most common allergy in asthmatics, and an important "root cause" for the development of asthma in young children. Recent studies suggest that at least 45 percent of young people with asthma are allergic to dust mite allergens. Unlike "seasonal" allergies caused by molds or pollen, people who are allergic to dust mites often will have symptoms year round.

Adult dust mites are about 0.5 mm long and the immature dust mites are even smaller. Consequently, they generally are visible only with the aid of a microscope. Collecting dust samples from inside the home and examining them under a microscope can confirm the presence of dust mites. Another diagnostic test more accessible to house-holders can be purchased from drug and allergy supply stores. An allergist-immunologist, via a skin and/or blood test, can confirm sensitivity to dust mites and their allergenic proteins.

Specific environmental requirements are required for these mite's development. The mites tend to be most numerous in warm homes with high humidity. Dust mites absorb and lose moisture through their skin, and are very vulnerable to dehydration. Consequently, humidity levels within the home have a significant effect on survival. Dust mites and their allergenic particles are present within homes year rounds, but people tend to have fewer symptoms during the summer, perhaps because they spend more time outdoors.

Food is seldom a problem for house dust mites. Their primary food is skin scales (dander) contained in house dust. People and pets regularly shed small flakes of skin from their bodies as the skin continually renews itself. Since the greatest fallout occurs in areas of human and pet activity, the mites tend to be most numerous in beds, overstuffed sofas and chairs, and adjacent carpeted areas. Relative humidity also tends to be higher in these areas, because people perspire and exhale water vapor where they sleep and lounge. Mattresses, sofas, carpet, and other soft furnishing trap and accumulate dust, dander, and moisture, making them ideal micro-habitats for mite development.

The allergenic proteins responsible for causing symptoms are contained within the mites themselves (alive or dead,) their shed skins, and especially in their feces. Routine human activity such as housecleaning, walking or playing on carpeting, or making the bed, causes the tiny fecal and skin particles to become airborne and inhaled.

One of the best approaches to patient therapy is to minimize exposure to the mites and their allergenic materials inside the home.

1. Attempt to lower relative humidity inside the home.
2. Maintain good levels of sanitation and housecleaning.
3. Encase your mattress and pillows in allergen-impermeable covers. Ideally, it's best to install dust-proof protectors on new bedding items rather than those that already laden with allergens.