We work with insects and ticks that transmit diseases. We study salivary proteins of vectors of disease, how insect salivary proteins and egested insect gut microbiota modulate the skin immune response and how this immune response affects pathogen establishment. We discovered insect salivary proteins that work as vaccines and salivary proteins that work as biomarkers of insect exposure. We also investigate how the Leishmania parasite develops inside the sand fly gut and the molecular determinants that make a sand fly infectious. We discovered a new parasite stage inside the gut of the sand fly and described how this stage augments the infectivity of the insect. To address these questions, we perform basic research in our laboratory, clinical studies at the NIH Clinical Center with human volunteers and field and clinical studies in disease endemic countries including Mali, Cambodia, Brazil, and Tunisia.