Diversity, Abundance and Leishmania infantum Infection Rate of Phlebotomine Sandflies in an Area with Low Incidence of Visceral Leishmaniasis in Northern Tunisia.

Abstract

We report the study of sandfly Leishmania infection in an area of low incidence of visceral leishmaniasis in Tunisia. Sandflies were collected monthly using CDC light-traps set in houses and animal shelters during May–November 2016 and 2017. All males were identified at the species level. A sample of 878 females including all gravid specimens was subjected to kDNA qPCR for Leishmania detection and parasite load estimation. Leishmania species were determined by ITS1 PCR sequencing, and species identification of infected sandflies was performed by DNA barcoding. Phlebotomus perfiliewi and P. perniciosus were the dominant species during the two-year period. However, comparison of their relative abundances showed that P. perniciosus was more abundant during peaks of 2017 with longer activity duration. Real-time kDNA PCR did not detect Leishmania infection in 2016, although it identified four positive specimens (0.7%) in 2017. All four infected specimens were identified as P. perniciosus. ITS1 PCR sequencing allowed L. infantum identification in one kDNA qPCR-positive specimen. This was a P. perniciosus gravid female with a high parasite load caught during the long-lasting peak of 2017. This work highlights the usefulness of multi-seasonal studies of sandfly dynamics and kDNA qPCR in screening Leishmania infection and determining L. infantum vectors in hypo-endemic foci of human leishmaniasis.