Macalester Reviews in Biogeography


The vector borne disease Leishmaniasis, caused by the Leishmania parasite, is estimated to affect the lives of 12 million people. Manifesting itself into three different clinical forms that center on disfiguring sores and enlargement of several organs, Leishmaniasis is a devastating disease impairing economic productivity and impeding socioeconomic development. The complex life cycle of this parasite, involving a host, vector, and reservoir, has played a major role in defining the dispersal and prevalence of this disease on a global level. The prevalence of Leishmaniasis is highly concentrated due to the close relationship of this parasite and its single vector (the female Phlebotomine sand fly), and the socioeconomic and environmental factors that are beneficial to the sand fly habitat. Yet, there is a wide and varied distribution of Leishmania species. Some species belonging to the subgenera of Leishmania are found in both Old and New Worlds, while others belonging to the subgenera Viannia are found only in the New World. Interest in the origin and dispersal of Leishmania has risen from this disjointed distribution and a need for a complete comprehensive understanding of this parasite in order to determine the best approach in the eradication of this disease. The two main hypotheses from the literature that have become established in this debate are a Palaearctic origin and a Neotropical origin. These hypotheses are presented along with a third hypothesis of an African and Neotropical origin. The conflicts between molecular, entomological, biogeographical, and ecological data, along with insufficient research that have rendered this debate unresolved are also discussed. Complexity of this diseases’ epidemiological cycle demands a comprehensive understanding of the parasite, including its origin and dispersal, to maintain the most effective prevention, treatment, and hopefully eradication.