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Demodex types, cycle and symptoms

According to experts, there are about 65 known species of demodex mites and only two types have been identified as regularly living on humans. Only Demodex folliculorum and Demodex brevis live in hair follicles and sebaceous glands on human skin. Demodex canis lives predominantly on domestic dogs but sometimes (not often) can occasionally infest humans.

Both demodex types are primarily found on facial area – preferably near the nose, forehead, chin, cheeks, eyebrows and eyelashes. Face skin provides the optimum temperature for mites to thrive. Demodex mites can also live in scalp hair follicles. Sometimes Demodex mites can be discovered around the ears and in skin folds.

Demodex types – Demodex folliculorum

Demodex folliculorum mites live in human hair follicles. Size of mature (adult) mites can be about 0.3-0.4 mm long with semi-transparent body. Sometimes fully grown mature mites can be seen with naked eye, but only microscopic examination can be used for proper diagnosis.

Demodex types – Demodex brevis

Demodex brevis live in human sebaceous glands which are connected to hair follicles. Size of mature (adult) mites could be up to 0.2 mm long with semi-transparent body. This type of mites can be visible only through microscope.

Demodex life cycle

Demodex eggs are laid 15-20 days after mating. Demodex legged larvae hatch 3-4 days after the eggs are laid. Transformation from larvae to mature mites takes one week. Total lifespan of demodex mites is about 15 days. Dead mites decompose inside the hair follicles or sebaceous glands – this waste usually compose Demodex acne.

Demodex mites eat skin cells, hormones and sebum (all accumulated in the hair follicle). Usually mites try to avoid light and only during night they leave sebaceous glands and hair follicles – coming out to mate. Unfortunately eggs are not possible to wash because they are laid deep in the hair follicles and deep in sebaceous glands. This is why usually day time local treatment is not so effective and best treatment should be organized at night time (night anti-Demodex creams).

In general, effective Demodex treatment should last minimum 12 weeks to be able to stop whole demodex life cycle.

It is very important to identify which type of Demodex mite exists on the skin (subcutaneous) because treatment methodology can be different. It is important to highlight that incorrect treatment could end up with mites spreading and ongoing infections.

There we catch Demodex

Demodex types, cycle and symptoms

Most people acquire Demodex mites shortly after birth and they become a part of normal skin fauna for the rest of life. At the beginning there are only few mites and later during puberty period sebaceous glands produce more oily food (sebum) for mites and mite population start multiplying. Usually number of Demodex mites can increase with aging.

At night mites move very slowly (about 1 cm per hour) and they can transfer between people through skin contacts or hair contacts. In most cases this transferring is happening during night sleeping time (especially if people sleep in the same bed close to each other).

In dry environment (away from their host) Demodex mites can survive only few hours but in wet environment (wet towel, wet clothing or wet pillow) they can survive for longer. In general, Demodex mites can live up to 58 hours in a drop of oil or in sebum from a sebaceous glands.

Demodex types – symptoms

In most cases mites don’t trigger any symptoms. But in older people with suppressed immune systems, in people with oily skin, in sick people (HIV, leukemia, chemotherapy) mite population can sometimes dramatically increase and get out of control.

The infestation causes so called “demodicosis” – the condition characterized by Demodex acne, redness, itching, inflammation or other skin disorders.

Demodex acne

Most common symptoms:

  • Rosacea,
  • Demodex acne,
  • Redness,
  • Dilated veins,
  • Large pores,
  • Blackheads,
  • Blepharitis (inflammation of the edge of eyelids).

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