Molecular Characterization of Visceral Leishmaniasis in Asymptomatic Dogs in North Khorasan, Northeastern Iran

background: leishmania infantum parasites are the main causative agents of visceral leishmaniasis that threaten a wide range of humans and canines in iran. objectives: our aim was to survey leishmania parasite species and simultaneous comparison of canine organs in endemic areas for the diagnosis of visceral leishmaniasis using the its-rdna gene, sequencing, and phylogenetic analysis. methods: in this study, sampling was done with vacuum tubes containing edta from blood and sterile swabs from the snout and conjunctiva of asymptomatic sheepdogs (n = 37) using a non-invasive method in north khorasan, northeastern iran, from 28 july to 4 august 2018. the dna of collected samples was extracted, amplified, and sequenced by targeting the its-rdna gene. to demonstrate the taxonomic status of leishmania spp., sequences were subjected to phylogenetic analysis basedonthemaximumlikelihood method. results:we obtained 37 samples from asymptomatic dogs of which, 10 dogs were definitely diagnosed with l. infantum and one dog infected with l. tropica. the blood (n = 8) and right conjunctiva (n = 6) samples were the most infected samples. the highest number of infections in dogs was in the age group of 5 - 10 years indicating that this group is more sensitive to visceral leishmaniasis in this region. conclusions: the current findings indicate that non-invasive sampling and molecular methods are reliable and suitable in the detection of visceral leishmaniasis. this is the first report of the visceral involvement of a shepherd dog with l. tropica in northeastern iran. the remarkable occurrence of visceral leishmaniasis (29.7%) in asymptomatic sheepdogs reflects a health alert to conduct the surveillance and monitoring of susceptible individuals/reservoirs in the region.