Favus is a mycotic disease in which smooth skin is affected. Hair, nails and internal organs are rarely affected. The disease is manifested by the presence of crusts and scales on the skin, alopecia, nail changes. Diagnosis is mainly laboratory: microscopic detection of fungus in scrapings. Treatment usually includes systemic antimycotic therapy, treatment of affected areas of the skin and removal of crumbled nail plates.
Favus is a fungal infection with a chronic course, affecting smooth skin, scalp, nail plates. The incidence is very high in countries with hot and humid climates. In our country, favus is diagnosed mainly in the central and southern regions, in areas where low temperatures prevail, disease is extremely rare. People with reduced immunity, reduced nutrition, concomitant endocrine diseases are mostly ill.
The causative agent of favus is the fungus Trihophyton schonleinii, which parasitizes only on humans, and therefore infection by animals is excluded. The main way of transmission of infection is contact and household. With close contact with a person with favus and in contact with his belongings (personal items, bath accessories, clothes and underwear), a large percentage of infections occur.
Since favus has a chronic sluggish character, it is mainly children who become infected through contact with mothers and grandmothers, since it is women who make up the majority of patients. Due to the fact that favus is less contagious compared to other fungal diseases, it remains unnoticed for a long time, although sick people continue to infect others. As a rule, favus is diagnosed accidentally during medical examinations or when seeking medical help.
The entrance gate for the causative agent of favus is the skin, and therefore microtrauma, abrasions, scratching and other violations of the integrity of the skin are provoking factors. Increase the risk of infection with favus:
- reduction of general immunity and protective functions of the skin;
- chronic diseases occurring with intoxication or cachexia.
Nutritional disorders and metabolic disorders are noted in almost all patients. Weakened children and children after infectious diseases are most susceptible to infection.
The causative agent of favus multiplies in the stratum corneum of the epidermis. Scutules characteristic are clusters of mycelium and fungal spores, exfoliated epithelium and sebum. As the favus spreads, the scutula becomes surrounded by leukocytes and exudate with destroyed epithelial cells. Further, the causative agent of favus penetrates into the dermis and causes the development of an infiltrate consisting of lymphocytes and fibroblasts.
At the final stage, irreversible atrophy of the epidermis develops, destruction of the sebaceous and sweat glands, collagen fibers and elastic tissues melt and postfavus scars form. After infection, the fungus can spread both along the length and hematogenously. In the latter case, favus lesions are noted in the internal organs.
The incubation period is two weeks, after which the first lesions appear on the smooth skin and / or scalp. The scutular form is classical and is diagnosed in most cases of lesion by the fungus Tr. schonleinii. The main clinical manifestations in the scutular form is the formation of dry round crusts of a saucer-shaped yellow or ochre color with a depression in the center. The scalp is affected, smooth skin, nails are rarely affected, in isolated cases, internal organs are affected in the scutular form.
Sometimes the scutules are located in the place of the hair follicle, then they are permeated with hair. Scutules formed during favus tend to merge to form solid crusts. As the favus progresses, the musty unpleasant smell of barn mold will join. In the absence of adequate favus therapy, cicatricial skin atrophy begins to develop under the crusts, and in particularly advanced cases, persistent postfavus baldness is observed. Areas of atrophied skin are smooth, shiny with a thinned stratum corneum.
The hair on the areas affected by favus becomes dull, loses elasticity and shine, is prone to breakage and to cross-section. With the onset of baldness, the remnants of hair look like tufts of tow. The peculiarity of the course of favus is that with baldness, the hair falls out, and does not break off as with other fungal diseases. At the same time, the hair is always preserved in the marginal zone. Sometimes the hair looks gray due to the spores of the favus fungus, this symptom is most noticeable in people with dark hair.
The impetiginous course of favus is characterized by the appearance of brownish-brown crusts, which are superficially similar to vulgar impetigo. With the squamous form of favus, there are scales of whitish-gray color, the affected areas are prone to abundant peeling of a lamellar nature. Sometimes the scales have a yellowish tint or are similar to dandruff, which makes it difficult to diagnose favus. Atypical clinical forms often go unnoticed, and yet it is precisely such patients who support the constant epidemiological focus.
Nail lesions with favus are more often diagnosed in adults, mainly the process passes to the nails due to autoinfection. First, a yellowish spot forms in the thickness of the nail plate, which gradually increases and grows until it covers the entire plate. For a long time, when the nails are bitten, the configuration of the nail plate does not change. But in the absence of timely treatment, the nail begins to thicken, deform and color. Peeling is noted on the skin of the palms and on the palm surface of the fingers without inflammation, cracks later join, which are often infected a second time.
In emaciated and weakened patients, in patients with hypovitaminosis and endocrine disorders, in the presence of tuberculosis-related intoxication and immunodeficiency, favus proceeds more aggressively. Extensive and deeper skin lesions are noted, the mucous membranes and lymph nodes are involved in the process. In particularly severe cases, favus affects the brain by the type of meningoencephalitis and the gastrointestinal tract with the appearance of numerous erosive and ulcerative defects.
The clinical picture allows the dermatologist to suspect the presence of a fungal disease and refer the patient to a mycologist. But only with careful examination and with the scutular form of the favus, it is possible to accurately diagnose based only on visual data.
Microscopy of hair, pieces of scutulae and scraping on fungi of the scalp skin reveals changes characteristic of favus, fungal spores and mycelium. With favus lesions, a thin and wide mycelium is found in the hair, the spores of the fungus have a rounded and multifaceted shape, are arranged randomly in groups and chains, there are air bubbles and inclusions of fat droplets.
Dermatoscopy and luminescent diagnostics can be used as auxiliary methods of diagnosis of favus. If the data obtained is not enough to make a diagnosis, then they resort to culture sowing with the release of a culture of the fungus on a nutrient medium. Favus should be differentiated with seborrhea, seborrheic eczema, pyoderma and generalized granulomatous candidiasis.
With lesions of the scalp favus, with a generalized form of favus involving downy hair in the process, the hair in the lesion is shaved off once a week and antifungal treatment of the scalp is carried out.
Antifungal ointments with cyclopyrox, which is active against all types of fungi, or other modern drugs with high activity and low toxicity are used locally. Since in most cases, local treatment is not enough for favus, a course of treatment is carried out, itraconazole is often administered orally. Crusts on the scalp are first softened with lotions of vaseline oil and after detachment of the stratum corneum of the epidermis, antifungal ointments are used.
If the nail bed is affected, then either varnishes with antifungal components are prescribed, or if the nail coloring has begun, surgical removal of the affected nail plates is performed and ointments and creams are used. At the same time, general restorative therapy is carried out, immunomodulators are prescribed, vitamins are taken. The effectiveness of treatment is evaluated after the absence of spores and mycelium by microscopic examination. Three negative results with an interval of 5 days indicate a complete cure.
Prognosis and prevention
Treatment of favus is long-term, but in the absence of lesions of internal organs, the prognosis is favorable. However, if postfavous baldness has begun, then it is usually irreversible. Prevention of favus consists in regular medical examinations, disinfection in the epidemiological focus and examination of contact persons.