What are "dust mites":

A Dust Mite is a small eight-legged animal that lives with humans in their "nests" and homes. The dust mite is the most common cause of allergic rhinitis and asthma on this planet. They eat microscopic molds and skin dander, and then leave their droppings (feces) behind. The dust mite droppings are the source of the irritating and allergenic effects of the mite. There is actually an enzyme in the mite feces similar to Adolf's meat tenderizer that can itself irritate a person, or cause an allergic reaction. So, people allergic to dust are really allergic to a bunch of dust mite do-do. In fact, house dust mites and their droppings are the most important cause of asthma worldwide.

• A dust mite is impossible to see with the naked eye
• 85% of asthmatics are allergic to dust mite droppings
• "Dust mite allergy" effects 10% of the population
• Damp and dusty homes are ideal breeding environments
• A house dust mite is 80% water
• The house dust mite does not bite

Symptoms
Are respiratory in nature, usually not a rash.  However, there are reports of a red rash around the neck.  The wheeze-inducing proteins are digestive juices from the mite gut and are potent.  An exposure to the mites in the first year of a infants life can trigger a lifelong allergy. 

There is no cure, only prevention. One must control the levels of dust mites.  Beds are a prime habitat, a typical mattress may have anywhere from 100,000 to 10 million mites inside.  Mites prefer warm, moist surroundings such as the inside of a mattress when someone is on it.  Their favorite food is dander (human skin flakes),  also, bedroom carpeting and household upholstery support high mite populations. Dust mites, due to their very small size (250 to 300 microns in length) and translucent bodies, are not visible to the unaided eye.  For accurate identification, one needs at least 10X magnification.  Through a microscope, one will see many oval-shaped mites scuttling around and over one another.  There are eight hairy legs, no eyes, no antennae, a mouthpart group in front of body (resembles a head) and a tough, translucent shell, giving a "fearsome appearance".

What is house "dust mite allergy"?

House dust mite allergy is a hypersensitive reaction to proteins in the excretion of dust mites. The protein attacks the respiratory passages causing hay fever and asthma. It will aggravate atopic dermatitis in people who have a tendency to this problem. The dust mites prefer to live in beds and, because we spend about a third of the day in bed, we inhale large quantities of dust mite allergens.

Controlling Dust Mites:

1. Use a high qualitity LifeTime electrostatic air filter in your forced air heating/cooling system.
2. Keep indoor humidity as low as possible, suggested at less than 50 percent.
3. Fix any water leaks or sources of moisture around the house, particularly in the basement.