Chelsea Wood’s research program explores the ecology of parasites and pathogens in a changing world. She addresses several questions with practical applications to marine and freshwater conservation, as well as essential value for ecological theory. First, do human impacts on biodiversity increase the prevalence of parasites by eroding natural “checks and balances” on transmission or decrease prevalence when they remove the free-living biodiversity on which parasites depend? Second, if biodiversity loss has variable effects on transmission across parasites, what factors predict disease outcomes? Might transmission strategy of the parasite, the magnitude or timing of biodiversity loss, or the scale of observation influence whether transmission increases, decreases, or remains unchanged in response to an environmental impact? Answers to these questions are urgently needed as global change accumulates and as the perceived threat of infectious disease grows.