Microsporia: causes, symptoms, diagnosis, treatment

Microsporia is a disease that affects the skin and hair, most often observed in children.

Causes and pathogenesis. Microsporia pathogens are divided into anthropophiles, zoophiles and geophiles according to their etiological features.

Anthropophilic microsporia is often caused by microsporum audouinii and microsporum ferrugineum, the causative agent of zoonotic microsporia is microsporum canis, s. lanosum.

Of the zooanthropophilic group, the most common pathogen of microsporia is Microsporum canis (source - kittens, dogs, children). Of the anthropophilic group, the most common pathogen of the disease is Microsporum ferrugineum (rusty microsporum), less common is Microsporum audouinii. In recent years, cases of human infection with Microsporum gypseum - a soil saprophyte belonging to the geophilic group - have become more frequent. It affects the skin and hair, primarily in people involved in soil cultivation.

Zoonotic microsporia. The source of infection is kittens sick with microsporia, less often - adult cats and dogs.

There are two peaks of the increase in the incidence of zoonotic microsporia - at the end of summer and in autumn, which coincides with two litters of cats, which in 2-3% of cases are carriers of the fungus without clinical manifestations. A person becomes infected through direct contact with sick animals or indirectly through contact with things, objects infected with wool and scales of animal skin.

Symptoms. The incubation period of the disease is 3-7 days. Smooth skin or the scalp are affected. When smooth skin is affected, multiple flaky pink spots of a round shape with clear boundaries appear. The clinical picture is very similar to superficial trichophytosis of the same localization. However, with microsporia, there are usually more foci than with trichophytosis and the disease is more acute. Vellus hair is affected in almost all patients. Microsporia of smooth skin is characterized by the appearance of pink spots of a round or oval shape 0.5-3 cm in diameter. In the peripheral zone of the spots there are blisters that quickly dry into crusts. The central part of the spots is covered with scales. Due to the centrifugal growth of the foci (with their simultaneous resolution in the center), individual elements acquire a ring-shaped form. Along with the old foci, new ones appear. In rare cases, new ones appear inside the old ring-shaped foci (the shape of a "target"). Microsporia of smooth skin is clinically indistinguishable from skin lesions in superficial trichophytosis.

When the scalp is affected, several large, sharply defined lesions of a regular round or oval shape (as if stamped) appear, covered with whitish scales. Usually, the inflammatory phenomena are not pronounced. In microsporia caused by downy microsporum, a continuous lesion of the hair in the lesion is most often observed. The hair in the lesion breaks off high (5-8 mm above the general skin level) and a white cap is visible at the base of the affected hair - these are fungal spores, which, like a muff, surround the affected hair.

For luminescent diagnostics of microsporia, a mercury-quartz lamp is usually used - stationary or portable with a uviol filter (glass impregnated with nickel salts). This filter lets through only short ultraviolet rays. Hair affected by microsporum (long and vellus) glows with a bright green light when irradiated with short ultraviolet rays in a dark room, and hair affected by rusty microsporum glows brighter. Considering that iodine and ointments extinguish the glow, the study is repeated 3 days after washing the patient's head. Nail plates are very rarely affected by both types of microsporia.

Differential diagnosis. The disease is differentiated from anthroponotic microsporia, seborrheic eczema, trichophytosis, favus, and Gibert's pink lichen.

Atroponotic microsporia is considered a more highly contagious disease than zoonotic microsporia. Infection occurs through direct contact with a sick person or through his headgear, clothing, comb, hair clipper. Children are most often affected. Infection is facilitated by hypovitaminosis, microtrauma, immune disorders.

Symptoms. The incubation period is 4-6 weeks. It occurs mainly in children. Anthroponotic microsporia of smooth skin resembles superficial trichophytosis: round, clearly defined lesions covered with scales, nodules and vesicles along the periphery, often forming inscribed rings. On the scalp, lesions are located mainly in the occipital, temporal and parietal regions. They are small, have clear boundaries, tend to be located in the marginal zone of hair growth, merge and form lesions of polycyclic outlines with fine-plate scaling. Hair breaks off at a height of 6-8 mm above the skin level and looks as if trimmed (hence the name "ringworm" lichen).

Differential diagnosis. The disease should be distinguished from zoonotic microsporia, seborrheic eczema, favus, trichophytosis, and Gilbert's pink lichen.

Diagnostics. The clinical diagnosis of scalp microsporia is confirmed by positive results of microscopic examination of hair, obtaining a culture of the pathogen and a distinct green glow of the affected hair during fluorescent examination. The diagnosis of smooth skin microsporia is confirmed based on the detection of mycelium and spores in skin scales from the lesions and a cultural study.

Treatment. Patients with multiple (more than three) lesions on the skin or with lesions of the scalp are subject to hospitalization. Of the systemic antifungals, griseofulvin, lamisil, and itraconazole are widely used.

Griseofulvin is prescribed at 22 mg/kg orally until the first negative fungal test is obtained during daily testing, then for 2 weeks the drug is prescribed every other day and then 2 times a week until clinical manifestations resolve and three negative fungal tests are obtained at intervals of 5-7 days.

Lamisil is used in the following doses: 94 mg for a child weighing 10-20 kg, 187 mg for a child weighing 20-40 kg, which is 1.5 times higher than recommended by the manufacturer, and for a child weighing 40 kg and above, as well as for adults - 250 mg.

Local treatment is prescribed for single lesions on the skin and without hair involvement in the pathological process. For external treatment, 3-5% iodine solution, 10% nitric oxide and sulfur ointment are used 2 times a day. A good therapeutic effect is noted when using 1% Zalain cream, Travogen, Mikospor and other antifungal agents. Of the antifungal drugs, the most effective is Lamisil in the form of a 1% cream or spray.

To prevent the disease, it is necessary to examine all family members clinically and under a fluorescent lamp. It is necessary to catch stray cats for examination. Quarantine is established in children's institutions for 2 weeks.

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