Hair Loss: Infectious Agents
Some people believe Demodex folliculorum contributes to hair loss and
that removing it will enable hair regrowth. But the organism does not cause
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 where there are lots of both.
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 repulsive, 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
Seborrheic dermatitis is first and foremost a skin condition, but it can
involve infection and temporary hair loss if the dermatitis is located on the
scalp or other skin areas. The dermatitis causes scaly, sometimes oily,
inflamed skin that can be itchy or even painful to touch.
This is an inflammatory condition that is not well understood, although
there does seem to be a genetic component and Caucasians, particularly of
Celtic descent, are most susceptible. Some newborns develop seborrheic
dermatitis when maternal androgens are passed from the mother to the baby
across the placenta. Conditions such as Parkinson's disease, head injury, and
stroke can also be associated with seborrheic dermatitis, and stress and
chronic fatigue can make it worse. Times of hormone fluctuation, such as during
puberty, can activate the onset.
In part, the trigger for seborrheic dermatitis may be androgen steroids. The
sebaceous glands attached to the hair follicles begin to produce a very rich
form of sebum. The sebum contains fewer free fatty acids and squalene but
increased amounts of triglycerides and cholesterol. The excess, rich sebum
production triggers the proliferation of skin flora. Yeast Pityrosporon
ovale (also called Malassezia furfur) has been shown to increase in
numbers with the intensity of seborrheic dermatitis. This excessive yeast
proliferation causes more irritation and inflammation.