Cutaneous leishmaniasis is an infectious disease caused by protozoa and accompanied by damage to the skin, less often the mucous membranes. A characteristic feature is ulcers at the site of the introduction of the pathogen. The temperature reaction of the body varies widely, other signs of the disease are detected very rarely. Diagnosis is based on the detection of the pathogen and antibodies to it. Treatment is carried out with the help of etiotropic drugs and symptomatic measures. In some cases, surgical intervention, cryodestruction or laser therapy is necessary.
ICD 10
B55.1 B55.2
General information
Cutaneous leishmaniasis is an infection transmitted mainly by transmissible means. This disease has been known since antiquity, was first described by the English doctor Pocock in 1745. The pathogen itself – Leishmania – owes its name to the English pathologist Leishman, who in 1903 described this protozoan almost in parallel with the Italian researcher Donovan. Pathology is common in tropical countries, seasonality is associated with the activity of vectors – from May to November.
Causes
The causative agent of the infection is the Leishmania parasite, which belongs to the protozoa. The most common species are L. tropica, L. major, L. aethiopica, L. infantum, L. mexicana, L. amazonensis, L. braziliensis. The reservoirs of parasites in nature are mosquitoes, raccoon dogs, sloths, rodents, foxes and porcupines. The main method of infection is a vector–borne pathway, implemented with the help of mosquito vectors, less often sand flies.
The microorganism needs a change of two hosts for reproduction, while the non–flagellar phase of development takes place in the body of humans or animals, and the flagellar phase takes place in the digestive tract of a female mosquito. When bitten, the carrier regurgitates leishmania into the wound, which are embedded in the thickness of the skin. Other ways of infection (vertical, with blood transfusions and surgical interventions) are rare. Risk groups for cutaneous leishmaniasis are children, rural residents, travelers, HIV-infected persons and cancer patients. Young men and elderly women are most often ill.
Pathogenesis
After penetration into the dermis, leishmanias are absorbed by macrophages, inside which they can multiply. To control the replication of the pathogen in the body, CD8+ T lymphocytes produce tumor necrosis factor and interferon gamma in large quantities, with the help of which the affected skin cells and macrophages begin to induce the production of their own microbicidal effectors capable of destroying leishmania. CD8+ lymphocytes play a significant role in the pathogenesis of the disease – they actively destroy the affected cells, but do not act on the intracellular parasites themselves.
The role of B-lymphocytes is being studied; a number of studies have shown the possibility of long-term persistence of the disease due to stimulation of CD4+ cells by B-lymphocytes and the occurrence of excessive production of both pro-inflammatory and regulatory cytokines. Histological examination reveals inflammatory infiltrates of variable intensity with diffuse or focal distribution, characterized by a predominance of lymphocytes, histiocytes and plasma cells with zones of spongiosis, parakeratosis and pseudoepitheliomatous hyperplasia. Ulcers, focal necrosis zone and well-organized granulomas are determined in the affected area.
Classification
Cutaneous leishmaniasis can be widespread (diffuse) or localized. Less common is the skin-mucous form of the disease (espundia), in which the mucous membranes of the mouth and nasopharynx are affected. In some cases, the respiratory tract is involved in the process, in particular, the larynx. In this variant of the course, disfiguration and deformation of the face occurs, death from respiratory failure is possible. The division of the disease into urban and rural leishmaniasis persists – it is believed that with the first type, the course of the ulcerative process is slower than with the second, and infection occurs due to sick dogs and rodents, respectively.
Symptoms
The incubation period of the urban form of pathology lasts from 10 days to a year, more often – 3-5 months; for the rural variant, the incubation time can be reduced to 1-8 weeks. The onset of the disease is gradual, with fever up to 38 ° C. Acute onset is characteristic of young children and HIV-positive patients, often leads to cutaneous visceral lesion and death. At the site of a mosquito bite, a brown-colored bump appears, which gradually grows to 2 or more centimeters, is covered with small scales (leishmanioma). Then the formation continues its growth and after six months ulcerates with the appearance of a characteristic mucopurulent discharge. The healing of the ulcer ends with the formation of a scar.
The rural form of the disease proceeds much faster and more aggressively: leishmaniomas almost immediately pass into the ulcerative stage with the formation of daughter tubercles, after 2-4 months the bottom of the ulcer begins to resemble fish eggs and centrifugal heal with the appearance of a scar defect. Lymphatic vessels become inflamed, palpated in the form of hard nodules-beads, some of which are opened. After the transferred urban skin variant, in rare cases, there is a chronic course of the process with the formation of small bumps near the scar, which do not ulcerate and can persist throughout a person’s life.
Complications
The most common complications of untimely diagnosed cutaneous leishmaniasis are areas of hyperpigmentation and scars at the site of leishmaniomas. In addition to a cosmetic defect, scarring can lead to disability (especially when located on the mucous membranes). Bleeding caused by the melting of the vessel at the bottom of the ulcer and secondary purulent processes are less common. With a long course, extensive lesion, comorbid pathology, the formation of chronic venous insufficiency, lymphostasis and recurrent erysipelas is possible. When the epiglottis is involved, a false croup may be observed.
Diagnostics
The diagnosis of the cutaneous form of leishmaniasis is verified by an infectious disease specialist, according to indications, consultations of other specialists are prescribed. A thorough collection of epidemiological anamnesis for staying in tropical zones is mandatory. During the diagnostic search, the following instrumental and laboratory techniques are used:
- Physical examination. Skin lesion in leishmaniasis is visualized as an ulcerative defect with raised edges, marginal “pockets” and purulent-serous discharge. The bottom of the formation may be granular, the shape is irregular. Sometimes daughter papules are visible. Inflamed lymphatic vessels are palpated in the form of dense knotted cords. Regional lymph nodes are rarely enlarged.
- Laboratory tests. There are no markers of cutaneous leishmaniasis in the general clinical blood analysis. With the addition of a secondary infection, leukocytosis is possible, with the transition to the visceral form – anemia, thrombocytopenia. Biochemical parameters are usually within the normal range. Changes in the general analysis of urine are uncharacteristic.
- Identification of infectious agents. PCR examination of the prints of skin ulcers and histological materials of papules makes it possible to detect leishmania. Microscopy, seeding of biological preparations, and bioassays are carried out to determine the pathogen. Blood ELISA indicates the presence of antibodies to the pathogen. The Montenegro intradermal test is an indirect method of confirming the diagnosis, used during the recovery period.
- Instrumental techniques. Chest X-ray or CT scan is indicated for patients with suspected tuberculosis lesion. Ultrasound of lymphatic vessels and nodes is performed for the purpose of differential diagnosis, soft tissue sonography is recommended for severe edema. Ultrasound of the abdominal organs is necessary if a combination with a visceral form of the disease is suspected.
Differential diagnosis of cutaneous leishmaniasis is carried out with anthrax, dermal plague, tuberculosis and tularemia. These diseases have manifestations in the form of ulcerative defects: painful (plague), with necrotic zones (anthrax), peeling edges (tularemia). Syphilitic chancre is usually located on the genitals and mucous membranes, painless, hard. Psoriatic plaques are areas of inflamed skin with silvery peeling. Systemic lupus erythematosus classically manifests as a maculopapular “butterfly” on the face, less often in the form of red discs with peeling.
Treatment
Patients with cutaneous forms of the disease do not need inpatient treatment. Bed rest is indicated for severe fever, pain syndrome and purulent complications. A special diet has not been developed, because of possible medicinal side effects, it is recommended to give up alcohol, narcotic drugs and nicotine, exclude difficult-to-digest food (fatty, fried, marinades) for the duration of treatment. Local antiseptic treatment of ulcers, mouth rinsing and washing of nasal passages with the location of foci on the mucous membranes, the use of sterile dressings with a daily change is indicated.
Specific antiprotozoal treatment is carried out taking into account the type of pathogen mainly with preparations of pentavalent antimony (sodium stibogluconate). It is possible to use miltefosine, pentacarinate, liposomal amphotericin B. The systemic use of these drugs is associated with the risk of side effects, therefore, local medications (creams, ointments) are currently being studied as a supplement to the main therapy. Symptomatic treatment involves taking antipyretics, painkillers, detoxification and other drugs. If leishmaniasis is resistant, splenectomy is performed.
Local treatment of leishmaniasis skin ulcers is inextricably linked with thermal exposure, since pathogens are extremely sensitive to high temperatures. Radiofrequency therapy is common among such therapies, the advantage of which is that there is no damage to healthy skin during application. Photodynamic and direct electrical therapy, infrared stimulation, laser therapy are used. There are descriptions of isolated cases of complete cure of cutaneous leishmaniasis using local techniques as nosology monotherapy in HIV-positive and other immunosuppressive patients.
Prognosis and prevention
The prognosis for cutaneous leishmaniasis in the absence of complications is usually favorable. Up to 85% of cases of the disease end in recovery; the disease is characterized by a cyclical course and natural convalescence. No fatal cases of leishmaniasis of this type have been recorded. Among HIV-infected and other people with immune deficiency, even weakly pathogenic strains of leishmania can cause visceral pathology. The duration of uncomplicated rural type of leishmaniasis of the skin is no more than 3-6 months, urban – up to 2 years. Treatment lasts for 20-30 days, therapy is allowed for up to two months.
Specific prophylaxis is indicated for everyone traveling to endemic areas, it is recommended to vaccinate in the winter-autumn season and no later than 3 months before the planned trip. The main means of non-specific prevention is vector control: drainage of basements and vegetable storages, insecticidal treatment, the use of repellents. Timely diagnosis, isolation and treatment of patients, installation of mosquito nets in wards is important. Routine vaccination of domestic dogs, the fight against urban landfills, deratization and shooting of sick wild animals are recommended.