Isolation and Molecular Typing of Leishmania infantum from Phlebotomus perfiliewi in a Re-Emerging Focus of Leishmaniasis, Northeastern Italy

Abstract

Visceral leishmaniasis (VL) caused by Leishmania (L.) infantum is a public health threat in the Emilia-Romagna region, northeastern Italy, but its epidemiology has not been fully elucidated in this area. The objective of this study was to characterize Leishmania infection in sand flies collected in a re-emerging focus of VL in the Bologna province. During the summer of 2016, 6114 sand flies were collected, identified, and tested for Leishmania detection. Of the identified sand flies, 96.5% were Phlebotomus (P.) perfiliewi and 3.5% were P. perniciosus. Detected parasites were characterized by biomolecular methods (multilocus microsatellite typing and characterization of repetitive region on chromosome 31), and quantified by real-time PCR. The prevalence of Leishmania infection in individually-tested P. perfiliewi sand flies varied from 6% to 10% with an increasing trend during the season. Promastigotes of L. infantum were isolated by dissection in one P. perfiliewi female; the isolated strain (Lein-pw) were closely related to Leishmania parasites from VL cases in northeastern Italy, but differed from strains isolated in dogs from the same area. Our findings strongly support the vector status of P. perfiliewi for human VL in the study area.

Co-Circulation of Phleboviruses and Leishmania Parasites in Sand Flies from a Single Site in Italy Monitored between 2017 and 2020

“…It is noteworthy that previous molecular studies showed the circulation of two genetically distinct populations of L. infantum in the Emilia-Romagna region—one affecting dogs and the other circulating in Ph. perfiliewi and humans [ 13 , 14 , 16 ]. This suggests the existence of two overlapping transmission cycles that probably involve different reservoirs.…”

“…Between 2017 and 2020, we sampled a single site that had already been surveyed, beginning in 2012 (44°17′15″ N, 11°41′46″ E) [ 16 ]. This site was located in the hilly area of the Emilia-Romagna region (altitude 196 m) in the garden of an uninhabited building.…”

Occurrence of Phlebotomine sand flies (Diptera: Psychodidae) in the northeastern plain of Italy

“…It is noteworthy that P. perfiliewi had never been reported in these regions, although it is the most abundant species in the neighboring region (Emilia Romagna) [ 31 ] and in central [ 32 ] and southern Italy [ 33 ].…”

“…Phlebotomus perfiliewi is a proven vector of L. infantum and its presence was documented in several outbreaks of CanL in the Emilia Romagna region [ 28 , 29 ]. The presence of P. perfiliewi was also observed in outbreaks of human VL, caused by L. infantum strains other than those isolated from dogs [ 31 ]. This finding suggests the involvement of P. perfiliewi in a sylvatic cycle of leishmaniasis in which wildlife plays the role of reservoir [ 34 ] rather than dogs [ 31 ].…”

“…The presence of P. perfiliewi was also observed in outbreaks of human VL, caused by L. infantum strains other than those isolated from dogs [ 31 ]. This finding suggests the involvement of P. perfiliewi in a sylvatic cycle of leishmaniasis in which wildlife plays the role of reservoir [ 34 ] rather than dogs [ 31 ].…”