Detection of Leishmania infantum DNA in phlebotomine sand flies from an area where canine leishmaniosis is endemic in southern Italy

Phlebotomine sand flies (Diptera, Psychodidae) are vectors of Leishmania spp., among which Leishmania infantum is recognized as the main agent of human and canine leishmaniosis (CanL) in the Mediterranean area. In this study, females of Phlebotomus spp. (P. perniciosus, P. neglectus and P. papatasi) and Sergentomyia minuta were collected in a dog shelter of southern Italy, where CanL is endemic, and examined for Leishmania DNA. In total, 32 out of 56 of Phlebotomus spp. insects (57.1%) were found positive for L. infantum DNA by quantitative PCR (qPCR), with a mean parasite load of 1.9 x 103 promastigotes/ml among 23 positive P. perniciosus and 2.1 x 103 promastigotes/ml among five positive P. neglectus. Four P. papatasi, a species known to be refractory to L. infantum development, were also found positive. Among 216 S. minuta specimens examined, 25 (11.6%) scored positive for Leishmania tarentolae by conventional nested PCR; two (16.7%) of them were also positive for lizard blood, which is in agreement with the feeding preference of this phlebotomine species. Nine S. minuta (4.2%) were positive for L. infantum by qPCR, with a mean parasite load of 1.62 × 102 promastigotes/ml. The detection of L. infantum DNA in S. minuta may suggest that this species could acquire the protozoan, occasionally feeding on infected dogs. Further investigations need to clarify the potential role that S. minuta may have in the transmission of L. infantum to receptive mammal hosts.