Kennita
follicle mite, Demodex folliculorum (Simon) (Demodicidae)
Demodicids are mites that live in the sebaceous pores and hair
follicles, usually on the nose, forehead, cheek, and chin. However,
they may inhabit follicles, with or without hair, anywhere on the
body. When "blackheads" are squeezed out of the skin and
examined under the microscope, demodicids are sometimes found,
but there is apparently no evidence that the mites cause the
blackheads. Demodicids have a curious body form the long, striate
abdomen giving them a somewhat wormlike appearance (figure
323). Their legs are mere stumps. They have been found on as many
as 97% and 100% of adults examined in different surveys. Children
and adolescents are seldom infested. Among adults, those with oily
skin or who use cosmetics such as lubricating creams extravagantly
and fail to cleanse the skin properly are the ones particularly subject
to infestation (Ayres and Anderson, 1932; Ayres, 1963; Ayres and
Mihan, 1967; Morgan and Coston, 1964; Coston, 1967). Demodex
folliculorum infests hair follicles and D. brevis Akbulatova infests
sebaceous glands (Desch and Nutting, 1972). Both may be present
on the same individual, but D. folliculorum is the species that has
received the most attention.
Description and Habits. The mite is less than 0.4 mm long, and
usually escapes notice. Its developmental period is about 14.5 days
(Coston, 1967). Inflammation and secondary infection often result
when a large number of mites congregate in a single follicle. A
Demodex type of acne rosacea or "rosacea-like demodicidosis"
affecting the medial portion of the face is believed to result from
excessive numbers of follicle mites; it disappears rapidly following
the topical application of a suitable antiparasitic medication (Ayres,
1963; Ayres and Mihan, 1967; Morgan and Coston, 1964).
Bacteria have been located on the bodies of D. folliculorum,
suggesting the potential of this mite as a mechanical transmitter of
disease germs (English et al., 1970).
The follicle mite can cause an inflammatory condition of the eyelids
called demodex blepharitis. Many mites can be found clinging to or
migrating about on extracted eyelashes. As many as 25 mites have
been seen clinging near the root end of a single eyelash, "packed
together like sardines" (Coston, 1967). The infested eyelashes may
be soggy or waterlogged, and sometimes can be pulled out with
virtually no resistance (English,1971).
Kennita Watson | The bond that links your true family is not one of blood,
kwatson@netcom.com| but of respect and joy in each other's life. Rarely do
| members of the same family grow up under the same roof.
| -- Richard Bach, _Illusions_