Leishmania infantum is the causative agent of infantile visceral leishmaniasis in the Mediterranean region of the Old World and in Latin America, where it has been called Leishmania chagasi. It is also an unusual cause of cutaneous leishmaniasis, which is normally caused by specific lineages (or zymodemes). Wild canids and domestic dogs are the natural reservoir of this organism. Leishmania infantum is closely related to Leishmania donovani, and some authors believe that these two species are so close as to actually be subspecies of each other; however, phylogenetic analyses can easily distinguish between the two groups, although analysis has shown that some isolates of Leishmania donovani have been classified as Leishmania infantum and that the former includes a number of different genet