Two Leishmania species circulating in the Kaleybar focus of infantile visceral leishmaniasis, northwest Iran: implications for deltamethrin dog collar intervention.

Leishmania infantum is the causative agent of infantile visceral leishmaniasis (IVL) in the Mediterranean Basin and, based on isoenzyme typing of a few isolates from patients and domestic dogs, this parasite was considered to predominate in the Kaleybar focus of IVL in northwest Iran. However, in the current investigation only one out of five sandfly infections was found to be L. infantum, based on PCR detection and sequencing of parasite internal transcribed spacer (ITS) rDNA infecting Phlebotomus perfiliewi transcaucasicus. The four other infections were of haplotypes of L. tropica, the causative agent of anthroponotic cutaneous leishmaniasis in the Middle East and a parasite occasionally detected in the viscera of dogs and patients in Iran and elsewhere. The widespread distribution of L. tropica in the Kaleybar focus suggests that this parasite is not a transient introduction. Kaleybar has been used for a deltamethrin dog collar intervention to reduce the biting rates of the vectors of L. infantum and this has significantly reduced the incidence of Leishmania infections both in children and the domestic dog, the usual reservoir host of IVL. The implications of finding L. tropica widespread in the heart of the intervention area are discussed. Extensive and intensive typing of natural Leishmania infections is a characteristic of epidemiological investigations in the Neotropics and the current report indicates that this will also be necessary in some regions of the Old World.