Mites might cause mighty problems.

• Position: Skin Disorders - Demodex mites linked to human skin diseases

You are not alone. Most individuals have millions of mites living in their hair and on their skin. These microscopic bugs may be linked to thinning hair, acne, and other skin conditions. "Many people don't like the idea of bugs living in their hair or on their skin, and some get really bent out of shape just thinking about it," says Jerry Butler, professor of entomology, University of Florida Institute of Food and Agricultural Sciences, Gainesville. "For some folks, it's enough to make [their] skin crawl. And bathing won't wash them off."

Known as the Demodex mite, the bug lives in the hair follicles of 96-98% of people and feeds on oils, hormones, and fluids around the follicle. Butler has counted as many as 25 mites in a single hair follicle. These itty-bitty insects usually are harmless and live in balance with their human hosts. High populations of mites, however, can initiate a variety of problems. "When something causes the mites to reproduce at a higher rate, they can break out of the hair follicle and may cause acne, hair loss, and [various] skin conditions. In some cases, the interaction with mites causes skin to actually slough off."

Studies show the mini-mite to be associated with numerous types of skin complications, but researchers are reluctant to conclude they are a direct cause of those situations. While Demodex may cause certain problems, it also is possible specific skin conditions become a breeding ground for mites.

Explains Frank Flowers, professor of dermatology at the Health Science Center: "There is a tenuous link [among] Demodex, acne rosacea, and folliculitis. However, no skin disease in humans has been...