Demodex folliculorum

Demodex mites

The face and body of a person can be affected by parasites - mites of the demodex species (Demodex folliculorum), which are fed from fats of human skin.

These scanty creatures settle next to hair follicles on the face and other areas where there are hairs. They are also found in the ears, eyebrows and eyelashes of a person, in the hair covering the chest and even the genitals. The life expectancy of such a tick is two to three weeks.

This parasite has microscopic dimensions (up to 0.5 mm) and is opportunistic, as it lives on about 90% of the inhabitants of the Earth, but only 5-10% have demodecosis.

These are microorganisms from the spider family, a third of a millimeter in size. Infection occurs through direct contact with other people.

Often ticks of this species are harmless and for most people this is nothing more than an unpleasant thought. In other cases, however, ticks can be associated with a variety of skin and eye disorders, including rosacea, acne and blepharitis.

Infection with demodex, according to experts, does not show visible symptoms, but they can cause problems with the skin in people prone to such diseases.

The female lays about 15-20 eggs inside the hair follicle near the sebaceous glands. Of these, larvae develop, which turn into an adult eight-legged individual. The female remains in the same place, while the male tick leaves the hair follicle in search of a partner.

Their path through the body takes only 10 mm and, as a rule, traffic is more lively at night.

When the tick dies, it releases the bacterium bacillus bacterium, which causes inflammation of the skin of patients and leads to the most severe form of the disease - papulopustular rosacea.

Rosacea is a genetic condition that affects one in ten people, and it usually appears after the age of 30.

On the face there is dilation of blood vessels, redness and uncontrolled inflammation. It can then lead to red, painful, pus-filled spots that look like large acne.

Some patients who suffer from tick infestation may complain of itchy eyelids and eyebrows, especially with morning waking from sleep^[1].

Mites of the genus Demodex are saprophytes of human skin, however, there are reasons that contribute to their transition to a pathogenic form. Thus, exposure to high temperatures, ultraviolet radiation, unfavorable household and working conditions are attributed to external reasons; changes in the human immune system associated with diseases of the nervous, vascular, hormonal systems, gastrointestinal tract, violation of the functions of metabolic processes - to internal ones.

Demodecosis disease

Demodecosis is a common chronic parasitic disease caused by mites of the genus Demodex, affecting people and animals. This dermatosis ranks 7th in terms of incidence and accounts for 2-5% of all skin pathologies. More than 65 species of ticks are known, but until recently it was believed that only 2 of them live on human skin: D. folliculorum and D. brevis. By the end of the 2010s, information appears about the discovery of also Demodex canis individuals in humans.

The complication of demodecosis is the seventh most common among skin diseases and is 2-5%, its frequency in patients with rosacea is 88.7%, in persons with papulopustular dermatoses - 10.5%, and with perioral dermatitis - 58.8% [7-10]. According to the literature, demodecosis can be both an independent primary process and accompany diseases such as acneform dermatoses, folliculitis, seborrheic dermatitis, etc.

Diagnostics

In 2010, R. Segal and co-authors proposed using a dermatoscope as a diagnostic tool that allows you to see ticks on the surface of the skin. Bloodless research methods also include standardized biopsy of the skin surface with further study of the material using light or electron microscopy. Other atraumatic methods of investigation include the use of optical coherence tomography, which allows real-time assessment of the skin condition of patients in two projections, and confocal laser scanning microscopy of surface layers of skin in vivo, with the help of which a three-dimensional image can be obtained. The advantages of the methods are the non-invasiveness and comfort of the patient, as well as their high informativity. The use of these methods allows us to confirm the effectiveness of treatment according to the available diagnostic criteria, as well as to select and timely adjust medical appointments. In 2019, demodecosis therapy is carried out in stages, systemically with the inclusion of anti-inflammatory, antibacterial, desensitizing and other drugs, as well as preventive measures.

Treatment

The established empirical ideas about the treatment of demodecosis do not fully take into account the possibility of etiological therapy with drugs with acaricidal effect both as a monocomponent and as part of complex therapy. This is due to the fact that in the development of this disease, not only a violation of the function of histohematic barriers, but also the penetration of the vital products of parasites into the local blood microcirculation system can play a role. A decrease in local immunoresistance causes an increase in the number of parasites and an increase in their activity. This, in turn, can cause the accumulation of toxic substances in the vessels of the skin microcirculation, which reduces their elasticity, increases the permeability of the endothelium and the expansion of the vasculature. Local angioedema occurs, looking visually like rosacea. Because the etiology and pathogenesis of demodecosis are poorly understood, the antiparasitic effect and normalization of vascular component regulation of the histohematic barrier as treatment approaches should be considered.

Drugs used:

• Dacarcid ointment. According to preclinical studies conducted at JSC Retinoids, the experimental drug D-18 has a low degree of toxicity, which indicates its increased safety^[2].

• ivermectin 1% has contraindications such as individual intolerance, pregnancy, lactation, age under 18, as well as a number of side effects such as burning, irritation, itching, dry skin, contact and allergic dermatitis. The drug is limited in use in patients with liver disease.

Notes