Leishmania parasites, illustration - stock illustration

Amastigotes of Leishmania parasites inside macrophages, illustration. Leishmania sp. cause leishmaniosis, a tropical disease transmitted by bites from infected sand-flies. These are the non-flagellated amastigote form of the parasite. In humans flagellated promastigotes infect macrophages and are transformed into amastigotes. There are two forms of leishmaniosis. The first, cutaneous leishmaniosis, affects the skin giving rise to an ulcer at the site of the bite. This mainly heals naturally, although scarring may occur. The more serious, visceral leishmaniosis (kala-azar), causes fever and liver damage, and can be fatal.