Piedra (trichomycosis nodularis) appears when the hair fibers are infected by a fungus. The visible indicator of a piedra infection is development of solid nodules on hair fibers. Indeed, “piedra” means stone for Spanish. The nodules are a concretion of hyphae and fruiting bodies of the fungus, known as an ascostroma, from which the fungal spores are released.
According to the color of the nodules formed on the hair fiber, there are two basic types of piedra: black piedra and white piedra. Black piedra is due to the fungus Piedraia hortae and is mostly found in tropical countries, while white piedra is due to Trichosporon beigelii and is found mostly in Europe and Southern parts of the United States.
Piedra infection may affect hairs of the scalp, body, and genital areas. Usually the infection is relatively friendly. In parts of Malaysia, the nodules of black piedra are considered attractive and traditionally women encourage its growth by sleeping with their hair buried in the soil. However, when the infection is severe the fungus weakens the hair fiber, making it easy to break off. This can result in a patchy, distributed hair loss.Treatment generally associates shaving off affected areas.
Some people believe Demodex folliculorum commits to hair loss and that removing it will enable hair regrowth. But the organism does not cause hair loss.
Demodex is a little worm-like creature that likes to live on skin and in hair follicles. It feeds on dead skin and oils, so it particularly likes to live in hair follicles.
Humans are born free of Demodex, but during childhood, through contact with others, the skin can become infected with it. For the most part, we never know they are there. They are benign, if nasty, little creatures. The most common problem with Demodex is that they may cause irritation, particularly in the eyelashes. If you have itchy eyelashes, Demodex may be the problem. However, this is as much as Demodex can do to you. It does not cause hair loss.