What is Demodex ?
Demodex is a parasitic mite in the arachnid (arthropod) family. There are two species typically found on humans: demodex folliculorum and demodex brevis. Demodex folliculorum is found in hair follicles, while demodex brevis lives in sebaceous glands connected to hair follicles. Both species are primarily found in the face, near the nose, the eyelashes and eyebrows, but also occur elsewhere on the body.
Mites appear in nature in numerous species as per data from an epidemiological survey. They look like ticks or very tiny spiders and are often visible with the naked eye or with a magnifying glass. Their classification varies as well – they are not usually referred to as Demodex but just mites. Demodex, however, is not a species similar to the mites present on the skin of animals like horses, sheep, cattle, or pigs. Demodex is a species present purely on humans, on their skin, and is visible only with the use of a microscope. The mites are similar to silkworms. They have a head and body with four pairs of short legs, and their abdominal part is made of rings. There are two types of mites, named Demodex folliculorum (long) and Demodex brevis (short one). Demodex is one of the tiniest arthropods present on mammals and thriving near the inside of their hair follicles. This small parasite is identified in a form of about sixty-five species. The ones living on humans are Demodex folliculorum and Demodex brevis and also known under the name of eyelashes mites. Domestic dogs are often infested with Demodex canis. Demodex mites infection happens very often and often happens without any symptoms. They are sometimes the reason for some skin conditions. The new generation is made within 15 days. In their life cycle they breed by laying eggs, developing larvae, nymphs of two stages, and becoming adults to mate again and repeat the cycle.
The adult mites are only 0.3–0.4 millimetres long, with D. brevis slightly shorter than D. folliculorum. Both are characterized by oval shape of the body. They have four pairs of legs in front of the body, which provide excellent adhesion to the surface. The rear part of demodex body is ended with an annular abdomen. The demodex development cycle lasts from 18 to 25 days. The fertilized female lays about 24 eggs, which hatch into larvae. The larvae are transformed into nymphs, similar to adults but with only three pairs of legs. In the last phase of the cycle they develop into full adults with four pairs of legs and the ability to reproduce. Demodex usually preys at night, avoiding the sunlight. The mites feed on sebum, and secretions from the sebaceous glands and epithelial cells.
How does Demodex looks ?
Demodex zoomed under electronic microscope
Demodex zoomed under medical microscope
Demodex zoomed under electronic microscope
Symptons of Demodex
Demodicosis is characterised by itching and inflammation. The condition is often confused with contact dermatitis or other skin conditions. According to Chinese physicians who have conducted long-term studies of the parasite, its presence is the most likely factor responsible for the formation of acne rosacea – though this hypothesis has not yet been fully confirmed. According to the studies, 9 out of 10 people are carriers of the demodex but the majority do not have clinical symptoms or lesions on the skin. The problem affects people primarily with temporarily or chronically impaired immunity.
For full and correct diagnosis it is necessary to conduct a test which involves the skin sample being taken and analysed under a microscope.
Eyelashes and eyebrows may also be examined.
Typical symptoms examples:
Typical symptoms include:
- rash, acne, pustules, purulent lesions
- rash, boils, scabs,
- oedema / swelling around the lesions
- burning and / or itchy skin
- the feeling of tingling (moving demodex)
- keratosis (hyperkeratosis)
- scaling / dry skin
- loss of hair, eyebrows, eyelashes
- obstruction / blockage of sebaceous passages
- the formation of blackheads
- redness of skin / telangiectasia (widened blood vessels)
- ear passage infection (unpleasant)
- blepharitis (rear and / or front)
- skin infections caused by microorganisms
(anaerobic bacteria, streptococcus, etc.)
BODY AREAS MOST COMMONLY AFFECTED BY DEMODEX:
Demodex may hatch both near hair follicles and sebaceous glands (which are at once an endless source of food (sebum), and at the same time a safe place to hide.
Areas exposed to infections are mainly located in areas close to large number of sebaceous glands, such as:
- around nose
- around zygomatic bones
- eyelid (front and rear inflammation)
- external auditory canal
- around nipples area
- labia, penis, anus
Demodex viability grows with increasing temperature. Temperatures around 37 ° C are the most conducive for its development but the weakening of the activity can be seen already at temperatures close to 45C. Temperature of 54 ° C is lethal for demodex.
Individual parasites are spread along with the dust, through direct contact with an infected person, or by using the same cosmetic utensils, towels and clothes. Demodex infected clothes and used things that previously belonged to someone else may become the source if infection. It may also be spread with a blast of air, along with the dust. Parasite’ eggs particularly easy to adhere to oily surfaces, and then penetrate into the pores of the skin.
How does Demodex enter human skin? Why can it cause diseases?
The main sources of infection with Demodex are daily mutual contacts of uninfected people with infected ones or with items, and taking part in activities like hugging, kissing, sharing bedsheets or towels. When the infection happens, the mites infest the healthy skin and especially thrive in hair follicles and in sebum, the rich and appropriate temperature of sebaceous glands. The entire life cycle of mites takes part in sebaceous glands: they lay eggs there, move and causing itching, produce excrete, mate, and eventually die. Then their corpses change in liquid and decay within skin layers being at the same time the cause of skin irritation of mechanical and chemical kinds. The skin texture, as well, is attacked by a large amount of the substance from dead cells, and it may cause an allergic reaction. Skin lesions and inflammation in the form of spots, papules, itching, and aching, also referred to as acne, are often caused by a sudden discharge of a large amount of excretion from decaying bodies into the sebum.
Mites continue to reproduce uninterrupted in this kind of environment, triggering inflammations, scarring, dilation of follicles and capillary vessels, and even numerous plumps. In short, the skin becomes damaged and will stay like that without a correct diagnosis and exact treatment that stands a chance to restore its natural beauty. Enclosed: the Process of Demodex Entering Human Skin, and Human Facial Cases Picture.
As per the studies in the field of epidemiology, it is known that mites do not occur in newborns. The conclusion was that it is not a genetic condition, and it is caused by contact with infected people. The risk of infection increases as they grow and the contacts are more frequent. The rate of Demodex infection throughout the country is 60%. However, the infection rate does not mean that the same number of people will suffer from it- the prevalence rate is not equal to infection rate. The disease occurrence is determined by quantity of mites and individual person’s immunity level. The ones with low immunity are more prone to be infected. As it is revealed, high mite infection causes 2.44% of rosacea and 10.04% of acne. People are concerned the most with the loss of natural skin beauty and high rate of prevalence for the condition.