Opportunistic feeding behaviour and Leishmania infantum detection in Phlebotomus perniciosus females collected in the human leishmaniasis focus of Madrid, Spain (2012-2018)

Background An outbreak of human leishmaniasis due to Leishmania infantum has been registered in an urban area of southwestern Madrid, Spain, since 2010. Entomological surveys carried out in the municipalities of Fuenlabrada, Leganes, Getafe and Humanes de Madrid showed that Phlebotomus perniciosus is the only potential vector. In this work, an intensive molecular surveillance was performed in P. perniciosus females captured in the region between 2012 and 2018. Methodology/Principal findings A total of 1805 P. perniciosus females were analyzed for Leishmania infection, and 1189 of them also for bloodmeal identification. Eleven different species of vertebrate were detected by amplification and subsequent sequencing of the 359 bp cytb fragment. The most prevalent blood source identified was hare (n = 553, 46.51%), followed by rabbit (n = 262, 21.95%). Less frequent were cat (n = 45, 3.80%), human (n = 34, 2.90%), pig (n = 14, 1.20%), horse (n = 11, 0.93%), sheep (n = 3, 0.25%), rhea (n = 3, 0.25%), partridge (n = 1, 0.09%) and chicken (n = 1, 0.09%). The distribution of the blood meal sources varied between the different locations. Regarding L. infantum detection, PCR amplification of a fragment of kDNA, cpb gene and ITS1 region showed 162 positive specimens (8.97%). The highest infection rate was found in the municipality of Leganes (15.17%). Conclusions The results of this molecular survey in P. perniciosus, the only leishmaniasis vector in the outbreak occurred in southwestern Madrid region, showed its opportunistic blood-feeding behaviour, high infection rates and the differences between the different points. This study was an essential part of the intensive surveillance plan in the area and the results obtained have supported the implementation of control measures in the outbreak. Author summary Vector-borne diseases (VBD) comprise a pathogen-vector-reservoir relation, and control programs should take into account different factors involving this relationship. This study is focused on a leishmaniasis outbreak that has occurred in the southwestern Madrid region since 2010. An intensive molecular surveillance of the sand fly vector Phlebotomus perniciosus was carried out from 2012 to 2018 in 4 municipalities from the affected region: Fuenlabrada, Leganes, Getafe and Humanes de Madrid. The aim of this investigation was to discern how much the vector was infected and find out its blood-feeding habits in the different surveyed points. The results showed an important rate of infected sand flies and also that P. perniciosus presents an opportunistic blood-feeding behaviour, taking blood from many different hosts, depending on their availability and density. The results obtained in this surveillance helped the authorities to plan and implement more accurate and effective control measures in the area, reflecting the importance of applying molecular surveillance in VBD outbreaks.