One important group of arthropods linked to asthma and common allergies are house dust mites. In 1921, a link was suggested between asthmatic symptoms and allergy triggers and house dust, but it was not until 1964 that investigators suggested that a mite could be responsible. Further investigation linked a number of mite species to the allergen response and revealed that homes have more mites and, subsequently, more allergens. In addition, researchers established that fecal pellets deposited by the mites accumulated in home fabrics and could become airborne via domestic activities such as vacuuming and dusting, resulting in inhalation by the inhabitants of the home. House dust mites are distributed worldwide, with a minimum of 13 species identified from house dust. The two most common in the United States are the North American house dust mite ( Dermatophagoides farinae) and the European house dust mite ( D. pteronyssinus).
According to Lyon, house dust mites thrive in homes that provide a source of food and shelter. Most mites are found in bedrooms in bedding, where they spend up to a third of their lives. A typical mattress may have from 100,000 to 10 million mites in it. In addition, carpeted floors, especially long, loose pile carpet, provide a microhabitat for the accumulation of food and moisture for the mite, and also provide protection from removal by vacuuming. The house dust mite’s favourite food is human dander (skin flakes), which are shed at a rate of approximately 0.20 ounces per week.
House dust mites can be detected using diagnostic tests that measure the presence and infestation level of mites by combining dust samples collected from various places inside the home with indicator reagents Assuming the presence of mites, the precautions listed below should be taken if people with asthma and allergies are present in the home:
- Use synthetic rather than feather and down pillows.
- Change bedding and vacuum the bed base and mattress or use a professional company that provides this service on a regular basis.
- Use nylon or cotton cellulose blankets rather than wool blankets.
- Use hot (120°F–130°F [49°C–54°C]) water to wash all bedding, as well as room curtains.
- Eliminate or reduce fabric wall hangings, curtains, and drapes.
- Use wood, tile, linoleum, or vinyl floor covering rather than carpet.
- Purchase stuffed toys that are machine washable.
High powered or industrial grade HEPA vacuums such as those used by professional mattress cleaning companies have also been shown to be effective. A conventional vacuum tends to be inefficient as a control measure and results in a significant increase in airborne dust concentrations.
According to the U.S. Environmental Protection Agency (EPA) pets can be significant asthma and allergy triggers because of dead skin flakes, urine, faeces, saliva, and hair. Proteins in the dander, urine, or saliva of warm-blooded animals can sensitize individuals and lead to allergic reactions or trigger asthmatic episodes. Warm-blooded animals include dogs, cats, birds, and rodents (hamsters, guinea pigs, gerbils, rats, and mice). Numerous strategies, such as the following, can diminish or eliminate animal allergens in the home:
- Eliminate animals from the home.
- Thoroughly clean the home (including floors and walls) after the animal removal.
- If pets must remain in the home, reduce pet exposure in sleeping areas. Keep pets away from upholstered furniture, carpeted areas, and stuffed toys, and keep the pets outdoors as much as possible