The high level of species diversity in the genus "Lutzomyia", coupled with its high adaptability is leading to increasing risk of "Leishmania" transmission in the New World in response to global change. "Lutzomyia" sand flies transmit the disease in the tropics and subtropics, regions which are subject to high levels of deforestation associated with continual development. Deforestation, with the establishment of settlements at the periphery of primary or secondary forest, increases the risk of "Leishmania" transmission by creating a selection pressure for the adaptation of sand flies to these new peridomestic environments. In southern Brazil, for example, levels of cutaneous leishmaniasis are increasing as a result of the adaptation of three, formerly forest-inhabiting species ("Lutzomyia intermedia", "Lutzomyia whitmani" and "Lutzomyi migonei") following deforestation. Now, a disease which previously only affected forest workers is becoming more prevalent in urbanisations. Similar increases in risk factors are also driving higher rates of visceral leishmaniasis in north-eastern Brazil. Increased urbanisation, driven by climate change and socio-economic factors, is bringing the adapting sand flies into closer contact with both humans and the domestic canine reservoirs of the disease.