We performed a cross-sectional survey in humans to evaluate Lutzomyia longipalpis, i.e. sand fly vector, bite exposure association with Leishmania (Leishmania) infantum chagasi infection in Bujar? municipality, Northern Brazil, an endemic area
for visceral leishmaniasis. In recruited individuals, which were stratified by sex and age, we measured L. (L.) i. chagasi
parasitic loads with quantitative polymerase chain reaction (qPCR), exposure to sand fly bites with an anti-saliva immunoglobulin G enzyme-linked immunosorbent assay and performed immunological diagnostic tests, in order to evaluate the
association between exposure to sand fly bites, and infection. The prevalence increased from 11% when using immunological diagnostic tests to 28% when using qPCR, being around that value for all age classes, but children below 5 years
(40%) and people over 60 years (15%). The association between PCR-based L. (L.) i. chagasi prevalence and saliva exposure
was convex, reflecting the fact that at both high and low saliva exposure the PCR-based L. (L.) i. chagasi prevalence
decreases. This scenario indicates that low sand fly exposure is likely associated with low parasite transmission, while
high anti-saliva prevalence, i.e. a large sand fly bite exposure could be associated with anti-Leishmania protective
immune mechanisms driven by vector saliva and/or increased parasite exposure
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