Over 20 species infect humans, reservoir animal
Transmitted by the bite of infected female phlebotomine sandflies
Only a small fraction of those infected by Leishmania parasites will eventually develop the disease.
Parasitize in macrophage
3 main forms
Visceral (kala-azar and the most serious form of the disease)
Cutaneous (skin ulcers, most common)
2 forms: promastigote (in the vector sand fly), amastigote (in the mammalian host)
Sandfly injects promastigote into skin and are phagocytized by macrophages (or other types of mononuclear phagocytic cells) and transform into amastigotes which invade and multiply in cells of various tissues and infect other cells (particularly organs with large collections of macrophages e.g. spleen/bone marrow)
Sandfly takes blood meal, ingests macrophage with infected amastigote which transforms to promastigote in gut, divide and migrate to proboscis.
The disease affects some of the poorest people on earth, and is associated with malnutrition, population displacement, poor housing, a weak immune system and lack of financial resources.
Leishmaniasis is linked to environmental changes such as deforestation, building of dams, irrigation schemes, and urbanization.
An estimated 700,000–1 million new cases and 20,000 - 30,000 deaths/yr.