From the Center for Disease Control and Prevention (CDC)
Leishmaniasis is a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. It is classified as a Neglected Tropical Disease (NTD). Leishmaniasis is caused by infection with Leishmania parasites, which are spread by the bite of phlebotomine sand flies. There are several different forms of leishmaniasis in people. The most common forms are cutaneous leishmaniasis, which causes skin sores, and visceral leishmaniasis, which affects several internal organs (usually spleen, liver, and bone marrow).
Image: The sand flies that transmit the parasite are only about one third the size of typical mosquitoes or even smaller. On the left, an example of a vector sand fly (Phlebotomus papatasi) is shown; its blood meal is visible in its distended transparent abdomen. On the right, Leishmania promastigotes from a culture are shown. The flagellated promastigote stage of the parasite is found in sand flies and in cultures.