Leishmaniasis is an infectious disease caused by parasites of the genus Leishmania, present on all continents, except Australia and Antarctica, with more than 20 species already identified.
THE streaming of the disease occurs through the bite of an insect, the phlebotomine of the genus Lutzomyia, known popularly as mosquito straw, tatuquira, birigui, cangalhinha, white wing, hard wing and straw.
The mosquito transmits leishmania after it has stung an infected animal, usually wild animals, although there is already a description of infected domestic dogs. There is no person-to-person transmission.
After the mosquito bite, the protozoan is inoculated into the body, where it can reproduce locally or spread through the body. Leishmaniasis can manifest itself in various forms, detailed below:
- Cutaneous leishmaniasis or cutaneous form: It is usually caused by the species Leishmania amazonensis and Leishmania braziliensis. It is characterized by the presence of an ulcer that does not cause pain in the exposed areas of the body, with a rounded or oval shape, of variable size (from millimeters to a few centimeters) and raised edges. The incubation period (elapsed time between the insect bite and the onset of symptoms) is around 2 to 3 months, but may vary from 2 weeks to 2 years. There may be more than one lesion simultaneously (up to 20 lesions) and there is usually good response to treatment. In only 2% of cases, the disseminated form, characterized by the appearance of multiple papular and acneiform lesions (similar to pimples), involving several parts of the body, including the face and trunk, can reach hundreds. There may be fever, muscle pain, general malaise and weight loss. Although more extensive, it is a form that presents a good response to the treatment. There are some patients who are infected with Leishmania amazonensis and are unable to generate immune response. In these patients, diffuse cutaneous leishmaniasis occurs, in which nodular or plaque lesions occur, covering large extensions of the body, often associated with deformities and that respond poorly to treatment.
- Mucosal or cutaneous mucosal leishmaniasis: corresponds to approximately 3 to 5% of cases of cutaneous leishmaniasis. It is characterized by exacerbated and ineffective immune response, with tissue destruction of infection sites and poor response to treatment. It reaches the mucous membranes of the upper airways (nose, mouth) and does not cause pain. In general, it appears after healing of a cutaneous lesion, by the dissemination of the parasite by blood or lymphatic vessels. However, it can occur even without evidence of a cutaneous lesion anterior or concomitantly to a cutaneous lesion at a distance.
- Visceral leishmaniasis: chronic form characterized by systemic (from internal organs) involvement by the Leishmania chagasi. The incubation period lasts from 2 to 6 months. The infection can be with little or no symptom, from moderate to severe, leading the patient to death. Initial symptomatic cases present, anemia, splenomegaly (enlargement of the spleen), hepatomegaly (enlargement of the liver) and fever. Without proper diagnosis and treatment, the disease progresses and significant weight loss, liver and kidney impairment, continuous fever and a decrease in the number of platelets and leukocytes can occur, leading to hemorrhage, bacterial infections and death.
O diagnosis of cutaneous forms is based on the clinical characteristics of the lesion and the patient's epidemiological history. It is always recommended to perform biopsy of the lesion for diagnostic confirmation, although it is difficult to find leishmaniasis in the lesion.
In the case of the visceral form, samples of blood, bone marrow, liver, spleen or lymph nodes should be collected for parasite research. The intradermalation of Montenegro, which is a test performed with intradermal injection of leishmania antigens (proteins), can also be performed.
In case the patient has already come in contact with the parasite (is infected or has been), an inflammatory reaction at the site of injection appears. It may be positive after successful treatment and negative in the diffuse cutaneous form, since it depends on the individual's immune response. In cases of visceral involvement, the test is negative, becoming positive only after clinical cure.
Another option that helps the diagnosis is the serology, which detects the anti-Leishmania antibodies circulating in the blood of people who have already come in contact with the parasite. It is not diagnostic of current infection and is of no value in the absence of clinical symptoms compatible with leishmaniasis.
If you have symptoms such as those mentioned above, and especially if you live in an endemic area for leishmaniasis, you should seek a dermatologist or infectious disease specialist.
