Microsporia is a mycotic disease of the skin, hair and nail plates. The causative agent of microsporiasis is a keratinophilic mold fungus of the genus Microsporum, which parasitizes in keratinized substrates. There are about 50-70 cases per one hundred thousand people. Microsporium is seasonal in nature. Its incubation period is 4-6 weeks and ends with the appearance of red and swollen spots on the skin. Later on, new elements with the typical ring shape appear.
Since the microsporia pathogen is widespread in nature, infection is possible everywhere, but in regions with hot and humid climates, microsporia is diagnosed more often. The infection is transmitted by contact or through objects contaminated with fungal spores. Children aged 5-10 years are more often affected by microsporiasis, with the incidence among boys five times higher than among girls. Adults rarely suffer from microsporia, but if infected, the disease almost always heals itself due to the presence of organic acids in the hair that inhibit mycelial growth.
Entrance gates for the microsporia pathogen are microtraumas of the skin; dryness, scuffs and calluses also increase the likelihood of infection, as healthy skin without injuries is not available for fungus inoculation. The virulence of microsporia is low, so if hands are washed promptly, even those infested with spores, the disease will not occur. Frequent contact with the ground, wild animals, sweating hands and violations of the chemical composition of sweat and sebaceous glands secretion increase the likelihood of microsporiasis. Spores of the microsporia pathogen persist in the soil for one to three months.
Once infiltrated, the fungus begins to multiply and affects the hair follicle, after which the infection spreads to the entire hair, leading to the destruction of the hair cuticle, between the scales of which the fungus spores accumulate. As a result, mycelium of microsporia completely surrounds the hair, densely fills the bulb and forms a sheath around the hair.
Microsporiasis caused by the anthropophilic type of fungus has an incubation period of 4 to 6 weeks, after which a swollen red spot appears on the smooth skin, which is elevated above the surface, has clear outlines and gradually increases in size. The lesions then appear as pronounced rings of nodules, vesicles and crusts. The rings are usually inscribed into one another or overlap, sometimes tending to merge. The diameter of the rings in microsporiasis varies from 0.5 to 3 cm, and their number rarely reaches five.
In children and young women, microsporiasis may have a pronounced inflammatory reaction and slight desquamation of the lesions. In patients who are prone to atopic dermatitis, microsporia cannot be diagnosed in time, since the fungus often masquerades as dermatitis, and therapy with hormonal drugs only intensifies symptoms and provokes further spread of microsporia.
Microsporiasis of the scalp occurs in children from 5 to 12 years of age, and by the time they reach puberty, it goes away without a trace. This phenomenon is associated with a change in the chemical composition of sebum and the appearance of organic acids in it and in the composition of the hair, which are detrimental to the fungus. In children with red hair, microsporiasis is practically uncommon.
The lesions are located on the crown, parietal and temporal areas, usually presenting as 1-2 large foci up to 5 cm in diameter with indentations on the sides of smaller ones. A flaky area appears at the site of the lesion, as the fungus first affects only the mouths of the hair follicles. On close inspection, you can see white ring-shaped scales that surround the hair like a cuff. After a week, microsporiasis spreads to the hair and it becomes brittle and fragile. The hair breaks at a distance of 4-6 mm from the scalp, and the affected area looks as if it has been cut. Hair stumps are covered with fungus spores and appear powdered with a grayish-white color. When affected by microsporiasis, the hair is not restored to its original position because it loses its elasticity and elasticity. The scalp in microsporiasis is edematous, slightly hyperemic, and covered with grayish-white scales.
The suppurative form of microsporiasis is clinically manifested by nodes of soft consistency, which are located on the bluish-red skin. The surface of the nodules is covered with numerous pustules. When the infiltrate is pressed on, droplets of pus emerge through the holes. Inflammatory forms of microsporiasis occur if there is late medical attention, irrational therapy and self-treatment, as well as in the presence of serious comorbidities that reduce the body's defenses.
The clinical examination and a history of contact with animals are sufficient for a dermatologist to suspect microsporiasis. Dermatoscopy and scraping microscopy reveal mycelium and hair and skin changes characteristic of mycoses. But microsporiasis and trichophytosis appear identical in conventional microscopy, so this laboratory examination can only confirm the presence of fungal disease, but not the exact diagnosis.
Cultural diagnosis of microsporia by culture followed by identification of the pathogen is more informative, but requires more time, although it can help identify not only the species but also the genus of the fungus, as well as choose the most effective preparations for treatment. Luminescent examination allows you to quickly examine both a patient with microsporiasis and contact persons. The mycelium of the fungus glows green, but the cause of this phenomenon has not been studied. In the early stages of microsporiasis, the glow may not be present because the hair is not yet sufficiently affected. However, when the hair is removed and examined later in the root part, the glow is observed even at the end of the incubation period. The luminescent method makes it possible to identify the microsporia pathogen in the patient and those who have been in contact with it, as well as to evaluate the effectiveness of therapy.
Depending on the severity of the lesion, microsporias are treated with topical and general antifungal therapy. Topical creams, ointments and emulsions with antifungal drugs - terbinafine and others - are used, depending on the age of the patient and on the physiological condition. It should be borne in mind that some antifungal drugs, even topical, should be used with caution during pregnancy and lactation. New generation ointments and sprays used for treatment of microsporia lesions do not leave greasy spots on skin and clothes, which will allow patients to feel comfortable during treatment.
If there is a pronounced inflammatory reaction, combined preparations that contain antifungal and hormonal components are used. Alternating applications with ointments and treatment with iodine solutions, if there is no skin lesion, has a good therapeutic effect. Microsporiasis complicated by secondary infection is treated well with ointments containing betamethasone, gentamicin and clotrimazole. For deep lesions, preparations containing dimethyl sulfoxide are used.
Prevention of microsporiasis consists of regular examinations of children in kindergartens to detect patients, limiting contact with stray animals and observing personal hygiene. Acquiring pets without a veterinarian's examination can lead to intra-family outbreaks of microsporiasis, which requires a more careful approach to their purchase.