Some people spend much money on these problems with the understanding that they are caused by bacteria or fungus, instead of demodex.

Tulane University Research Laboratories has learned that, 88% of individuals with thin-looking hair have demodex. In contrast, individuals with normal hair density showed the opposite; 91% did not; 91 % did not have demodex.

Demodex is a tiny mite with eight legs, less than 0.1- 0.4 mm. long. Only two species of the mites which are specific human – associated mite are Demodex folliculorum and Demodex brevis.

Demodex folliculorum infiltrates into the hair follicles and takes the nutrients and may damage hair root structure. As a result it causes thin or unhealthy hair , hair loss and inflammation of the surrounding tissue.

Demodex brevis inhabits the sebaceous glands, particularly around the nose, eyelids and other facial area and feeds on the nutrients and oil in sebaceous glands. As a result, the sebaceous glands become infected and inflamed appeared as acne or rash .

With the presence of both demodex, the damage can be substantial. Entire life cycle of demodex is spent on the host. It breeds and multiplies fast. An individual female may lay up 12 - 24 eggs in the hair follicle. As the mites grow, they become tightly packed which may cause hair pore blocking and develop to infection at the hair pore. When matured, the mite leaves the follicles, mates and finds a new follicle in which to lay its eggs. The whole cycle takes between 14 to 28 days. During the daytime, mites remain within the follicle feeding on hair follicle nutrients. At night, they emerge onto skin surface to mate. Their moving may irritate nerve ending in the scalp which causes itching.

Furthermore, its legs with many joint carrying bacteria, virus and rickettsia can cause infection on the scalp and skin. Its secretion or dead cells may cause skin sensitization.

In addition it sharp claws may cause irritation to the epithelium cells of the scalp which leads to proliferation of epithelium that causes dandruff or scaling.

Demodex transferred from host to host by contact, particularly in hair, eyebrow and tiny sebaceous glands on the nose. The transmission from dogs to human can occur, but it is very uncommon.