Dust mites spread through the activities of humans and pets but are not parasitic. They feed on skin dander from humans and animals and require humidity levels of 70 to 80 percent to thrive. Most homes have measurable levels of dust mites, according to the University of Kentucky.
Dust mites are tiny animals related to ticks, chiggers and spiders. They are a problem for humans because their feces and shed skins trigger allergic reactions. They tend to concentrate in mattresses, pet bedding, upholstered furniture and adjacent carpeted areas. To control dust mites, homeowners should encase mattresses and pillows in allergen-impermeable covers, wash bedding weekly in hot water, remove carpeting and upholstered items if possible, and use high efficiency particulate arrestor filters in vacuum cleaners, central air and heating systems, and portable air conditioners.