Climate change and pandemic disease are two of the most daunting challenges of the twenty-first century. In this new era with the potential for increased temperatures and climate variability, controlling the spread of infectious diseases will require a deep understanding of how climate variation influences parasitic diseases. Most studies of climate-disease interactions have focused on mean temperature and precipitation, ignoring short-term climate fluctuations. This approach assumes that neither parasites nor their hosts acclimate to temperature shifts, despite evidence that such acclimation responses are pervasive in ectothermic hosts. Accounting for these acclimation responses could dramatically alter predictions of climate-disease models, particularly for diseases with ectothermic hosts and vectors (e.g., malaria). However, there is currently no quantitative theory describing parasite and host acclimation responses to temperature shifts. Johnson and his colleagues will fill this important gap in knowledge by (1) developing a mathematical model describing how temperature variability influences parasitic infection, (2) parameterizing this model in a trematode-tadpole system using a series of controlled temperature experiments, and (3) testing quantitative predictions of the model across different timescales of temperature variability in artificial ponds. Their central hypothesis is that parasites acclimate to temperature changes more rapidly than their hosts because of their smaller sizes and faster metabolisms, leading to higher infection rates under variable-temperature conditions. This project will also train undergraduate, graduate, and post-doctoral research scholars and promote science awareness through public outreach and workshops for K-12 teachers.