Biodiversity loss has the potential to affect infectious disease risk by disrupting complex ecological interactions between pathogens, vectors, and hosts. However, whether biodiversity loss generally increases or decreases disease risk remains the subject of contentious debate. In my thesis, I addressed this fundamental issue by studying the interactions among communities of hosts, ticks, and associated pathogens in Panama, a biodiversity hotspot under threat. Using a DNA barcode reference library specifically designed for this study, I first examined the distribution and diversity of ticks across a wide range of vertebrate host species, quantified tick-host specificity, and explored which host biological and ecological traits could explain tick parasitism. Then, I assessed how changes in wildlife community composition affected the abundance and diversity of ticks, their microbial communities and, ultimately, tick-borne disease risk. My results suggest that the relationship between biodiversity loss and disease risk is non-linear, and that the presence of specific host species is more important than species richness per se for tick population and tick-borne disease dynamics.