The role of sloths and anteaters as Leishmania spp. reservoirs: a review and a newly described natural infection of Leishmania mexicana in the northern anteater.

For years, mammals of the order Pilosa have been considered Leishmania reservoirs. But while most studies have focused on sloth species, anteaters have been overlooked, and in many Leishmania endemic countries like Mexico, no studies have been carried out. The aims of this work were to identify the presence of Leishmania spp. in tissue samples from road-killed northern tamanduas (Tamandua mexicana), using PCR amplification and sequencing of ITS1 DNA, and to discuss the role of Pilosa mammals as reservoirs of Leishmania based on available scientific records. This is the first study that identifies Leishmania in T. mexicana, from 1 of 16 individuals analyzed, so the estimated prevalence (CI 95%) of infection was 6.3% (0.3-27.2). Amplified sequence exhibited a 98.9% (727/735) similarity with L. mexicana, and phylogenetic analysis grouped the species in the L. mexicana-amazonensis cluster. The literature review revealed 241 cases of Leishmania spp. infection among 1219 Pilosa mammals evaluated, with prevalence between studies ranging from 3.5% in the brown-throated three-toed sloth (Bradypus variegatus) to 78% in the Hoffman's two-toed sloth (Choloepus hoffmanni). Current scientific information indicates that C. hoffmanni sloths are reservoirs of Leishmania, and further studies are needed in order to clarify if other Pilosa species play a role in Leishmania transmission.