Leishmania

Leishmania are dimorphic intracellular protozoan parasites of vertebrates that are transmitted by the bite of the phlebotomine sandfly vector. Leishmania are one of several genera in the family Trypanomastidae (which includes the important human pathogens in the genus Trypanosoma). Their complex life cycle dictates an interesting cell biology, as well-documented cellular and biochemical changes must occur within these parasites as they prepare for the transition from life within the fly to survival in the vertebrate host. As is the case for all Trypanomastidae, their molecular biology is fascinating and has helped to reveal novel mechanisms of RNA processing and uncommon mechanisms of gene regulation. Species of Leishmania have also become an important model for studying the pathogenesis of intracellular parasitism and the subversion of the host's immune system for the benefit of the parasite. The leishmaniases are a diverse set of zoonotic diseases in which humans are incidentally infected. Multiple species of Leishmania are known to cause human diseases of the skin, mucosal surfaces, and organs of the reticuloendothelial system. Cutaneous leishmaniasis is usually mild, but may be cosmetically disfiguring. Visceral and mucosal diseases have a significant morbidity and mortality. The drugs used in treating these diseases are only partially effective, which underlines the importance of preventing exposure to sandflies. Currently, no effective vaccines exist for any form of leishmaniasis, although there is reason to believe that an effective vaccine could be developed in the future.