The Role of Demodex

Abstract

The human integument provides a favorable substrate for the growth of bacteria, certain yeasts, and, in relation to the current topic, even mites. Most of these com-mensals live with us, and flourish and nourish themselves in our hair follicles, but curiously not within eccrine or apo-crine sweat glands and their acrosyringa. Our skin may be likened to a botanical and zoological garden, supporting a diversity of species. Mites of the species Demodex folliculorum and Demodex brevis prosper in the deep, large sebaceous follicles. It is rare to find a person in whom Demodex cannot be demonstrated after vigorous examination. Demodex is absent in children and surprisingly sparse in adolescents and young adults, even in oily persons. De-modex has an aversion for acne lesions, and is never found in comedones. Over the next three to four decades their numbers increase. The prevalence approximates 100% in older adults. However, it should be emphasized that the population density is low. To locate a few mites takes a lot of effort. Demodex folliculorum are closely associated with sebaceous glands. They utilize sebum as nourishment. Their feeding grounds are, therefore, the spacious canals of the sebaceous follicles and seba-ceous ducts. The best site to search for mites is the face. The nose, cheeks, forehead , temples, and chin are favorite locations , along with the balding scalp and neck.