The sand fly genus "Lutzomyia" includes all species responsible for transmission, in the New World, of the "Leishmania" parasite; the causative agent of leishmaniasis. Of the more than 350 "Lutzomyia" species identified, less than 10% are known or suspected to transmit leishmaniasis to humans. The disease is in endemic in 22 countries of tropical and subtropical America, where it is generally considered a zoonosis. That is, the parasite cycles between mammalian reservoir hosts and the sand flies, with humans serving as incidental, dead-end hosts. Common reservoirs in the Americas include a number of rodent species, as well as dogs, sloths and armadillos. The "Lutzomyia" sand flies maintain transmission amongst reservoir species and allow the disease to ‘jump’ to humans, causing the visceral, cutaneous or mucocutaneous forms of the disease depending on the "Leishmania" species. Visceral Leishmaniasis is a serious form of the disease in particular that affects the internal organs. This specific disease is primarily transmitted by the species "Lutzomyia longipalpis". The human-sand fly-human cycle of transmission, known as anthroponotic, is limited to two "Leishmania" species endemic in the Old World and so does not involve "Lutzomyia" sand flies.