Just over 30 years ago, a new species ofLeishmaniaof the subgenusLeishmania(Viannia) was described infecting the armadilloDasypus novemcinctus; then, a report of human infection followed. From the Brazilian Amazon and apparently restricted to this region and its close borders,Leishmania(Viannia)naiffihas been characterized as a species that grows easily in axenic culture medium and causes few to no lesions after inoculation in experimental animal models. Results in the last decade indicate the occurrence ofL.naiffiin vectors and human infections, including a report of therapeutic failure possibly associated withLeishmaniaRNA virus 1. Overall, such accounts suggest that the parasite is more dispersed and the disease less self-healing than previously expected.Graphical Abstract