Leishmania

Leishmania is a genus of parasitic protozoa responsible for the disease leishmaniasis, which affects humans and other mammals. These single-celled organisms belong to the family Trypanosomatidae and are transmitted primarily through the bites of infected female sandflies belonging to the Phlebotomus and Lutzomyia genera.

Leishmania exists in two main morphological forms: the promastigote, which is the flagellated form found in the sandfly vector, and the amastigote, a non-flagellated form that infects host cells. During a blood meal, the promastigotes are injected into the host’s skin and are ingested by macrophages, where they transform into amastigotes and multiply within immune cells. This intracellular lifestyle allows the parasite to evade host immune responses.

Leishmaniasis manifests in several clinical forms, most notably cutaneous, mucocutaneous, and visceral. Cutaneous leishmaniasis causes skin ulcers and lesions, while mucocutaneous leishmaniasis can affect mucous membranes of the mouth and nose, leading to disfigurement. Visceral leishmaniasis, also known as kala-azar, affects internal organs such as the spleen, liver, and bone marrow, often resulting in fever, weight loss, and anemia, and can be fatal if untreated.

Diagnosis typically involves laboratory techniques such as microscopy, culture, or molecular methods like PCR. Treatment may include antimonial compounds, amphotericin B, or miltefosine, with the choice dependent on disease form and geographic factors. Control measures focus on vector management, reservoir control, and improving sanitation to reduce transmission.

Leishmania infections are endemic in parts of Asia, Africa, the Middle East, and Latin America, posing significant public health challenges in these regions.