NSF Award
2243076
Parasites are often spread unevenly across space, where some host populations have few parasites and others are heavily infected. This pattern is common, but still poorly understood and poses a considerable barrier to accurately predicting and managing diseases. This is especially true for parasites that have complex life cycles or move between different host species. This includes many parasitic worms (helminths), which infect over two billion people worldwide and cause serious disease in livestock, yet have been historically understudied. This project connects empirical data with mathematical models to understand and predict how behavior, immunology, and ecology within each host species shapes parasite transmission across space and through time. This research focuses on a well-studied tapeworm system which infects fish-eating birds (Loons), copepods, and threespine stickleback fish in freshwater lakes. By integrating field studies, laboratory experiments, genetic studies, and mathematical models across all three hosts and the parasite itself, this project provides a detailed understanding of the transmission of a complex-life cycle parasite and builds a modeling toolkit that can be applied to other parasites. To share this work, the investigators have developed an art-science collaboration involving indigenous artists and a science journalism student to produce a traveling exhibition focused on this project. Research is also being incorporated into the classroom through a course-based undergraduate research experience, an interdisciplinary undergraduate course focused on the connections between art and science, a high school summer science program, and is being made broadly available through published lesson plans.<br/><br/>Parasite transmission is shaped by a complex interplay of ecological, behavioral, and immunological factors, yet our understanding of how these factors interact and their relative impacts on disease prevalence across scales remains fragmented. The project develops a general framework, informed by empirical data, for understanding and predicting how these different processes operate within multiple hosts and shape parasite transmission and distribution across space and time. This work addresses four main questions: (1) What are the relative contributions of parasite exposure (a dose-response) versus immunity on transmission dynamics? (2) How sensitive are exposure and immunity to environmental variation, namely resources and host population structure? (3) To what extent is parasite abundance driven by local factors or landscape-level patterns of parasite dispersal? (4) Is the uneven distribution of parasites driven more by traits of the first, second, or tertiary host? Using the model tapeworm system, S. solidus, this research develops and applies cutting-edge statistical and mathematical approaches and a global sensitivity analysis to large temporal and spatial datasets spanning multiple levels of biological organization. This project builds on our knowledge of the well-studied threespine stickleback host and filling in important missing information for the other two hosts in this system (loons and copepods). This research produces a general, yet mechanistic, modeling framework to better understand transmission in this system, as well as inform work with other complex life cycle parasites.<br/><br/>This project is supported by the Division of Environmental Biology, Division of Integrative Organismal Systems, and Division of Mathematical Sciences.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
