Cutaneous leishmaniasis: causes, symptoms, diagnosis, treatment

Cutaneous leishmaniasis (synonyms: Old World leishmaniasis, Borovsky's disease) is an endemic transmission disease, occurring mainly in countries with hot and warm climates, and manifested mainly by skin lesions.

Causes and pathogenesis of cutaneous leishmaniasis. The causative agent is the protozoan Leishmania tropica. The carriers of the disease are various types of mosquitoes. There are mainly two types of leishmaniasis: anthroponotic (urban type), caused by Leishmania tropica minor, and zoonotic (rural type), caused by Leishmania tropica major.

The source or reservoir of infection of the rural type of cutaneous leishmaniasis are rodents and gerbils, and of the urban type - a sick person.

Cutaneous zoonotic leishmaniasis is characterized by seasonality, i.e. the disease occurs in summer and autumn, while the anthroponotic type occurs all year round.

It is found mainly in Central Asia and Azerbaijan. The main reservoirs of the infection are rodents (gophers, gerbils), and the carriers are mosquitoes. There are two types of the disease: rural, or acute necrotizing, caused by Leishmania tropica major, and urban, or late ulcerating, caused by Leishmania tropica minor. In rare cases, a tuberculoid (lupoid) variant is observed, which usually occurs in the area of previously regressed lesions in the urban type of leishmaniasis due to the reactivation of surviving leishmania, caused by general or local immune disorders.

The rural type is acute, furuncle-like elements develop at the site of the bites, after ulceration of which crater-like ulcers appear, scarring within 3-8 months. Lymphangitis is characteristic.

In the urban type, the development of elements of a smaller size is observed than in acute necrotizing leishmaniasis; they exist for a long time (5-6 months) without ulceration, and heal slowly (on average, within 1 year). The duration of the inflammatory process is associated with the predominance of lymphocytes with suppressor properties in the infiltrates.

Symptoms of cutaneous leishmaniasis. Cutaneous leishmaniasis occurs cyclically: primary (stage of tubercle, ulceration, scarring), sequential (early, late), diffuse-infiltrating leishmaniomas and tuberculoid are noted.

Leishmaniasis is cutaneous zoonotic. The incubation period is from one week to two months. At the site of the mosquito bite, a painful, flattened, acutely inflammatory tubercle of a bright red color, 3-5 mm in size, is formed. The tubercle turns into a furuncle-like infiltrate with unclear boundaries. The infiltrate increases in size, reaching 10-15 cm in diameter, and after 2 weeks its central part quickly undergoes necrosis, necrotic masses are rejected and a small crater-like ulcer (5-8 mm in diameter) is formed, with purulent discharge, around which there is a wide zone of infiltrate with inflammatory edema of the surrounding tissue.

Later, the bottom of the ulcer is cleared of necrotic masses and red papillary granular growths appear, resembling caviar. The ulcers are round, oval or irregular in shape, their edges are sometimes smooth, undermined, sometimes scalloped, as if eaten away. New ulcers appear around the main one. Specific complications of cutaneous leishmaniasis include lymphangitis around ulcers and lymphadenitis. Dense, slightly painful nodes appear from the upper edge of the ulcer, the size of a small pea to a hazelnut. Later, the inflammation in these nodes may intensify and lead to ulcerative decay. Bead-shaped lymphangitis is noted on the extremities. The process is accompanied by pain, the development of edema of the feet and shins. After 3-6 months, the process ends with scarring.

Cutaneous anthroponous leishmaniasis. The incubation period is from 3 to 6 months (rarely - up to 3 years). At the site of introduction of the pathogen, leishmanioma appears in the form of a smooth, slowly growing brownish-red tubercle 1-2 mm in size. Gradually, the tubercle grows, protruding above the skin level, and after 6 months reaches 1-2 cm in diameter.

In the central part of the element, a crater-like depression is observed, which has horny scales, which are sometimes impregnated with exudate and turn into scaly crusts. In 6-8 months after the rejection of the blood-purulent crust, an ulcerative defect is formed. The ulcer is round, surrounded by a raised infiltrate, with an uneven reddish bottom, corroded edges, a scanty serous-purulent discharge dries into a brown crust. New tubercles and seeding ulcers may appear around the ulcer. Bead-shaped lymphangitis is observed on the extremities. Approximately in a year (sometimes more), the infiltrate decreases, the ulcer clears up, islands of granulation tissue appear and it begins to cicatrize.

Sometimes the healing of granulation tissue occurs under the crust in a dry way. The general condition of the patients is not disturbed.

Tuberculoid leishmaniasis is a variant of leishmaniasis that develops in individuals with altered reactivity of the body as a result of activation of surviving leishmania or as a result of natural superinfection. This type of leishmaniasis is often found in children or young people. The disease develops either in the process of regression of primary anthropophilic leishmanioma or in the area of a postleishmanial scar. Around the healing lesion, tubercles appear, 2-5 mm in size, yellow-white in color with a sign of congestive redness. The elements have a hemispherical flat shape, with a smooth, sometimes flaky surface. Tubercles often surround a fresh scar, can develop on an already formed scar and persist for a long time. The appearance of new elements contributes to an increase in the affected area, capturing new areas of the skin. Then, in the process of regression, they leave atrophy or can ulcerate, becoming covered with a yellow-brown crust. In appearance, the tubercles resemble lumps in tuberculous lupus, which is why the disease is often called lupoid leishmaniasis.

In our country, American cutaneous leishmaniasis, the causative agent of which is Leishmania brasiliens, has also been described in a patient who arrived from an endemic zone. This form of leishmaniasis differs from Borovsky's disease by frequent lesions of the mucous membranes of the upper respiratory tract, oral cavity, the presence of early (at the site of bites) manifestations characterized by ulcerating tubercles and nodes, and late manifestations, occurring after several years, in the form of granulomatous-destructive and ulcerative lesions.

Pathomorphology. In the acute period, an infiltrate consisting mainly of macrophages filled with a large amount of the pathogen is found in the dermis, among them are lymphoid and plasma cells. In ulceration, neutrophilic granulocytes are also found in the infiltrate, leishmania can be not only inside the macrophages, but also outside them. After several months, foci of a tuberculoid structure appear, the number of macrophages and leishmania decreases. In the chronic course of the process, an infiltrate of a tuberculoid structure is found, difficult to distinguish from tuberculosis. However, the absence of caseous necrosis and the presence of plasma cells, as well as leishmania help diagnose leishmaniasis. In the tuberculoid form of leishmaniasis (metaleishmaniasis), the histological picture reveals signs of both an acute and a chronic process. In the dermis there is an infiltrate of macrophages with an admixture of lymphocytes and plasma cells and tuberculoid structures. Leishmania is rare.

Histopathology. Grapulema infiltrate consisting of epithelioid cells, lymphocytes, and histiocytes is detected. Pirogov-Langhans type giant cells are visible among the epithelioid cells.

The diagnosis is made based on the detection of leishmania in the lesions.

Differential diagnosis is carried out with tuberculosis, syphilis, pyoderma, sarcoidosis.

Treatment of cutaneous leishmaniasis. Antibiotics are prescribed - monomycin, doxycycline, meta-iclin, antimalarial drugs - delagyl, plaquenil (including for injection of unopened leishmaniomas). Cryodestruction and laser therapy are performed. There are reports of the effectiveness of lamisil (250 mg per day for 28 days).

Individual prevention consists of using mosquito protection (canopies, nets, treatment with repellents). Public prevention consists of eliminating mosquito breeding sites, mosquito treatment (focal disinfestation), and extermination of gerbils (in the case of the zoonotic type).

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ]