Phlebotomine sand fly fauna characterization and Bartonella bacilliformis DNA detection in Pintomyia (Pifanomyia) robusta at the Ecuador-Peru frontier

Phlebotomine sand flies are blood-sucking dipterans widely distributed in tropical and subtropical areas of the Americas and are important vectors of leishmaniasis caused by Leishmania spp. parasites and Carrion's disease caused by the bacteria Bartonella bacilliformis. Both are a significant economic burden in rural areas and a major risk to military personnel deployed to endemic areas. To better understand transmission of these pathogens and epidemiological trends, sand flies were collected from nine sites across the Ecuador-Peru border region in 2015 and 2017 and screened for Leishmania using PCR targeting kinetoplast DNA, and Bartonella using PCR targeting the 16S-23S internal transcribed spacer (ITS) region, citrate synthase (gltA) gene, and NADH dehydrogenase subunit G (nuoG) gene. A total of 548 sand flies belonging to 15 species and 2,711 sand flies belonging to 11 species were collected in Ecuador and Peru, respectively. Pintomyia (Pifanomyia) robusta was generally the most abundant species found across sites sampled in Ecuador and Peru. In the Chinchipe River basin, Pi. (Pif.) robusta, Pintomyia (Pifanomyia) maranonensis, and Lutzomyia (Helcocyrtomyia) castanea were collected on both sides in Zamora-Chinchipe, Ecuador, and Namballe, Peru. Of the 637 phlebotomine sand fly pools screened, no Leishmania positives were found; however, nine pools of Pi. (Pif.) robusta collected in Ecuador were positive for B. bacilliformis based on phylogenetic analysis of the gltA gene. One Pi. (Pif.) maranonensis from Peru and one Pi. (Pif.) robusta from Ecuador were positive for Bartonella DNA sequences that were close to Candidatus Bartonella rondoniensis based on gltA. This is the first reported detection of B. bacilliformis DNA in Pi. (Pif.) robusta, providing evidence for the role of this sand fly species in transmission of this pathogen at the Ecuador-Peru border.