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Posted on Sep 23, 2012 in Blepharitis | 0 comments

Types of Demodex Parasites that Affect Facial Skin, Hair Follicles and Cause Blepharitis of the Eye

Demodex mites are parasites of the humans genus that live in the facial skin and in hair follicles of the infected. There are over 60 types of Demodex mite, but there are only two that eat humans. Any others that hop onto human skin will look for a new host. They may eat a little of your dead skin and skin oil, but will soon find a new host. This can be seen with people who handle animals with mange. They may often find that they have dry skin on their arms and elbows shortly after dealing with the animal, but the dryness promptly clears up after 2 weeks. If it does not, then you should consult a doctor as it may be caused by something else.

There are two species, Demodex folliculorum measuring 250-300 microns and lives in hair follicles of the eyelashes and Demodex brevis, of shorter length (150-200 microns), who lives in the sebaceous glands. Both can be found in the eye area, but Demodex folliculorum are the ones that enjoy eating the nutrients from the follicle roots. The brevis species of mite enjoys eating the oil and tears produced around your eyes.

During their life cycle these parasites destroy the skin and eyelashes absorbing nutrients from the root of the hair, damaging the cell walls, excreting waste, laying eggs and dying within the follicles.

Their life cycle lasts about ten days and consists of five stages: Egg

The infestation may be asymptomatic. There are many people who are walking around and are infested with Demodex mites, but show no signs of them being affected. There are innumerate reasons for this, one of which may be diet. People whom eat a lot of garlic are often less affected, even when heavily infested. Other reasons include things such as genetics, a strong immune system, a built up immunity, smaller oil glands, and many more reasons. The sad thing is that people may have contact with this person and then become heavily infested themselves.

A demodex infection may produce a broad spectrum of clinical manifestations; there is a direct relationship between the degree of parasitism and intensity of symptoms. Thus for a full parasitological study is necessary to conduct a quantitative study indicating the rate of parasitism.

Among the clinical manifestations that may be produced by the overpopulation of Demodex in eyelashes, there are the suppurative and granulomatous reactions. These include things such as:

Chronic inflammation
Eyelid redness
Loss of eyelashes
Scaling of the eyelids

Follicular inflammation produces edema, facilitating the extraction of the eyelashes. It is often observed in addition to a collar of epithelial tissue surrounding the base of the eyelashes.

Both species of Demodex induce pathological changes associated with dry eye because when there is follicular plugging meibomian gland (D brevis) or in the glands of Zeiss (D. folliculorum or D. brevis) is a decrease of the surface layer of the tear duct lipid. D. brevis has also been implicated in the formation of chalazion. The infestation of eyelids by Demodex species may or may not accompany dermatologic changes in the nose, cheeks or forehead.

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