Mites might cause mighty problems - Skin Disorders - Demodex mites linked to human skin diseases

USA Today (Society for the Advancement of Education), Feb, 2004

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 conclusively linked with these mites." Flowers indicates that one of the most effective treatments for these disorders is metronidazole cream. "The link between mites and hair loss and other skin conditions is not conclusive, but we do know it's a major problem for dogs," Butler adds. "If you have high revels of hormones, you're going to have high levels of mite reproduction because these anthropods obtain their steroids from the host."

Butler warns that Demodex poses the biggest threat to people under stress or those with cancer or other conditions such as HIV/AIDS that suppress the immune system. Mite colonies can spread unchecked because patients cannot produce the antibodies needed to control the parasites. "Under normal conditions, mites produce an antigen when they feed in a hair follicle, and then the human body makes antibodies against the bugs, thereby keeping their reproduction low and in balance. The mites are actually needed to make the antigen that stimulates the body into making protective antibodies."

Butler notes that mites feed continuously inside the hair follicle. Three to five days are required for egg laying and hatching, followed by seven days for the larvae to develop into adults. Their total life span is probably several weeks. They are transferred from host to host by contact, particularly in hair, eyebrows, and tiny sebaceous glands on the nose.