Demodex brevis is a type of mite that lives in the oil glands of human hair follicles. It is closely related to Demodex folliculorum, another type of mite. Collectively, D. brevis and D. folliculorum are referred to as Demodex.
The mites are microscopic, meaning they are not visible to the naked eye. While most people with D. brevis are not even aware that they are carrying these mites, those housing large infestations may experience symptoms.
Keep reading to discover the symptoms of Demodex brevis and the treatment options available to manage these mites.
D. folliculorum also inhabits the follicles. Unlike D. brevis, it is mostly found on the face and around the eyelids and eyelashes. It feeds on skin cells, whereas D. brevis feeds on oil called sebum in the oil gland cells.
D. folliculorum is different from other types of mites because it can increase the number of skin cells in hair follicles. This can give people the appearance of scaly skin.
The average D. folliculorum mite measures 0.3 to 0.4 millimeters (mm) in length, while the D. brevis is half that size, at 0.15 to 0.2 mm.
Most people with Demodex brevis are only carriers of the mites — they do not develop symptoms.
However, large infestations of the mites may lead to symptoms such as:
- red, scaly skin
- a rough texture to the skin, like sandpaper
- a burning sensation in the skin
Typical areas of infestation include the neck and chest.
D. brevis does not usually lead to complications, but large numbers of mites (over 5 per square centimeter of skin) may cause demodicosis.
Demodicosis is an inflammatory skin disease, with symptoms including:
- color changes in the skin
- scaly skin
- red skin
- sensitive or irritated skin
- rash with papules and pustules
- eye irritation
- loss of eyelashes
It should be noted that while demodicosis is dangerous in canines, there do not appear to be any reports of human demodicosis being life threatening.
D. brevis is acquired after birth through physical contact. Once on the body, the mites feed off the oil gland cells that are attached to hair follicles.
Numbers of D. brevis increase naturally, which may be why they are present in higher numbers in older adults than in children.
Anyone can have D. brevis. However, there are some factors that increase the likelihood and severity of a Demodex infestation.
Older adults are also more likely to have Demodex mites and experience complications such as demodicosis.
Demodex brevis is most common in people aged 20 to 30 years because sebum levels are at their highest during that period. The mites are rarely seen in children under 5 years of age due to low sebum production.
Additionally, D. brevis and D. folliculorum seem to be more common in men than in women, although it is not clear why this is the case.
Most people are not aware they have Demodex mites living in their follicles. Many people only become alerted to their presence when being tested for other skin conditions.
It is not necessary for a person to get tested for the mites unless they experience symptoms or complications.
A doctor can diagnose demodicosis with a biopsy. This involves taking a small skin sample and checking it under a microscope.
The doctor will also ask about symptoms and look for other signs of the mites, such as scaly skin.
Demodicosis will be diagnosed if there is a high level of mites in the follicles in addition to skin symptoms.
Most cases of Demodex mites can be treated at home. Medical intervention may be necessary if someone is experiencing uncomfortable symptoms.
There may be several ways to minimize the number of D. brevis mites on the skin, and to reduce the risk of complications. Personal care tips include:
- bathing daily to reduce the oil secretions that feed the mites
- washing the hair and eyelashes with a mild shampoo
- using a non-soap gentle cleanser on the face twice daily
- avoiding oily cleansers, lotions, and sunscreens
If home remedies do not relieve symptoms or reduce mite numbers, then medication may be necessary to reduce excess sebum on the skin.
The medications for Demodex brevis and the mite eggs can be taken orally or applied to the skin. These medications are used off-label for this condition and include:
- benzyl benzoate
- oral or topical ivermectin
- topical metronidazole
- salicylic acid
- selenium sulfide
- sulfur based medications
In severe cases of mites, or for people with weakened immune systems, a doctor may recommend oral ivermectin.
It is also important to manage any underlying conditions, such as immunosuppressing conditions like HIV, that may be contributing to high levels of mites.
While it may be unpleasant to think of mites living in the skin and hair follicles, they are usually harmless and do not cause symptoms in most people.
However, large numbers of Demodex brevis can lead to uncomfortable symptoms known as demodicosis. As a result, it is important to keep numbers under control through simple personal hygiene steps. However, for some individuals, a weakened immune system may be the provoking factor (not poor hygiene).
Those who are experiencing skin symptoms such as redness, itching, or scaling in areas where Demodex tends to exist in high quantities should consult their doctor about whether their rash is related to this specific mite.