Wild canids and domestic dogs are the natural reservoir of this organism.

[5] The sandfly species Lutzomyia longipalpis serves as the primary vector for the transmission of the disease.

[6] 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;[7] however, phylogenetic analyses can easily distinguish between the two groups despite no difference in morphology in the species complex.

[2][8] Comparative bioinformatic analyses showed that the size of the L. infantum BRCA2 protein is approximately three times smaller (125 kD) than its human counterpart.

The smaller size of the Leishmania BRCA2 DNA repair protein has been exploited to better understand its function in homologous recombination and its interaction with the LiRAD51 recombinase.