Four Leishmania species (L. major, L. infantum, L. donovani and L. braziliensis) have been fully sequenced.
Leishmania major is a species of parasites found in the genus Leishmania, and is associated with the disease zoonotic cutaneous leishmaniasis (also known as Aleppo boil, Baghdad boil, Bay sore, Biskra button, Chiclero ulcer, Delhi boil, Kandahar sore, Lahore sore, Oriental sore, Pian bois, and Uta). L. major is an intracellular pathogen which infects the macrophages and dendritic cells of the immune system.
Though Leishmania species are found on every continent aside from Antarctica, Leishmania major is found only in the Eastern Hemisphere, specifically in Northern Africa, the Middle East, Northwestern China, and Northwestern India.
Upon becoming infected, patients usually present with lesions at the site of the sand fly bite. The infection is acute, and usually has a duration of about 3–6 months. As more and more phagocytic cells engulf promastigotes, prompting the production of amastigotes, nodules form on the skin. These nodules then ulcerate, due to the variable characteristics of the lesions, species specific identification of the pathogen is impossible by traditional means.