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.