Transmission of Leishmania infantum by Rhipicephalus sanguineus (Acari: Ixodidae) in Dogs

Background: Rhipicephalus sanguineus is the most widely distributed tick in the world, which is partly due to its biological flexibility and the global distribution of its major host, the domestic dog. In Mediterranean region it could be principal reservoir host for Leishmania infantum, usually transmitted by the phlebotomine sand flies. In this study, we evaluated the vector potential of R. sanguineus in transmitting L. infantum to uninfected dogs. Methods: During 2014, five dogs with clinical manifestations of canine visceral leishmaniasis (CVL), high anti-Leishmania antibody titers and tick infestation, were selected from CVL endemic areas (Tehran and Alborz provinces). At least, twenty live ticks were removed from each infected dog. After morphological identification, the ticks were divided into two groups; ticks belonging to the first group were dissected for parasitological examinations and semi-nested PCR assay, and those of the second group were selected for the transmission of CVL caused by L. infantum to uninfected dogs. Following tick infestation, all uninfected dogs were kept for 9 months and examined monthly for clinical and serological tests. Results: Nearly, 67% of ticks were infected by L. infantum using the semi-nested PCR. All other parasitological tests of ticks were negative. Clinical examinations and serological tests of the investigated dogs revealed negative results. Nested-PCR test results performed on splenic biopsy samples of dogs were also negative. Conclusion: L. infantum-positive R. sanguineus ticks were unable to transfer L. infantum from infected dogs to healthy ones. The detection of L. infantum DNA in ticks collected from naturally infected dogs by semi-nested PCR does not prove their vectorial competence.