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Leishmaniasis is a disease caused by parasites of the Leishmania type. It is spread by the bite of certain types of sandflies. The disease can present in three main ways: cutaneous, mucocutaneous, or visceral leishmaniasis. The cutaneous form presents with skin ulcers, while the mucocutaneous form presents with ulcers of the skin, mouth, and nose, and the visceral form starts with skin ulcers and then later presents with fever, low red blood cells, and enlarged spleen and liver.
Infections in humans are caused by more than 20 species of Leishmania. Risk factors include poverty, malnutrition, deforestation, and urbanization. All three types can be diagnosed by seeing the parasites under the microscope. Additionally, visceral disease can be diagnosed by blood tests.
Leishmaniasis can be partly prevented by sleeping under nets treated with insecticide. Other measures include spraying insecticides to kill sandflies and treating people with the disease early to prevent further spread. The treatment needed is determined by where the disease is acquired, the species of Leishmania, and the type of infection. Some possible medications used for visceral disease include liposomal amphotericin B, a combination of pentavalent antimonials and paromomycin, and miltefosine. For cutaneous disease, paromomycin, fluconazole, or pentamidine may be effective.
The symptoms of leishmaniasis are skin sores which erupt weeks to months after the person is bitten by infected sand flies.
Leishmaniasis may be divided into the following types: Cutaneous leishmaniasis is the most common form, which causes an open sore at the bite sites, which heals in a few months to a year and half, leaving an unpleasant-looking scar. Diffuse cutaneous leishmaniasis produces widespread skin lesions which resemble leprosy, and may not heal on its own. Mucocutaneous leishmaniasis causes both skin and mucosal ulcers with damage primarily of the nose and mouth. Visceral leishmaniasis or kala-azar ('black fever') is the most serious form, and is potentially fatal if untreated. Other consequences, which can occur a few months to years after infection, include fever, damage to the spleen and liver, and anemia.
Leishmaniasis is considered one of the classic causes of a markedly enlarged (and therefore palpable) spleen; the organ, which is not normally felt during examination of the abdomen, may even become larger than the liver in severe cases.
Leishmaniasis is diagnosed in the hematology laboratory by direct visualization of the amastigotes (Leishman-Donovan bodies). Buffy-coat preparations of peripheral blood or aspirates from marrow, spleen, lymph nodes, or skin lesions should be spread on a slide to make a thin smear and stained with Leishman stain or Giemsa stain (pH 7.2) for 20 minutes. Amastigotes are seen within blood and spleen monocytes or, less commonly, in circulating neutrophils and in aspirated tissue macrophages. They are small, round bodies 2–4 μm in diameter with indistinct cytoplasm, a nucleus, and a small, rod-shaped kinetoplast. Occasionally, amastigotes may be seen lying free between cells. However, the retrieval of tissue samples is often painful for the patient and identification of the infected cells can be difficult. So, other indirect immunological methods of diagnosis are developed, including enzyme-linked immunosorbent assay, antigen-coated dipsticks, and direct agglutination test. Although these tests are readily available, they are not the standard diagnostic tests due to their insufficient sensitivity and specificity.
Several different polymerase chain reaction (PCR) tests are available for the detection of Leishmania DNA. With this assay, a specific and sensitive diagnostic procedure is finally possible. The most sensitive PCR tests use minicircle kinetoplast DNA found in the parasite. Kinetoplast DNA contains sequences for mitochondrial proteins in its maxicircles(~25-50 per parasite), and guide RNA in its minicircles(~10'000 per parasite) of the kinetoplast. With this specific method, one can still detect Leishmania even with a very low parasite load. When needing to diagnose a specific species of Leishmania, as opposed to only detection, other PCR methods have been superior.
more: https://en.wikipedia.org/wiki/Leishma...
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