Mammalian community motifs as a driver of tick-borne disease hazard in urban environments

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Abstract

Understanding how host community composition influences tick-borne disease (TBD) risk is critical for predicting and managing public health in urban environments. Current disease ecology frameworks suggest that increasing biodiversity can impact transmission risk, depending on host reservoir competence and ecological interactions. However, mammalian community dynamics can mediate TBD risk in complex ways. Urban areas, with their unique gradients in habitat connectivity and species composition, provide an opportunity to explore how mammal community structures impact the density of infected nymphal ticks (DIN), thereby influencing TBD transmission. Our research leverages a multi-city approach using the Urban Wildlife Information Network to investigate these dynamics. We hypothesize that urban forest patches connected to peri-urban areas will support synanthropic mesopredators (e.g., raccoons, foxes) that reduce rodent populations, potentially diluting LD risk by decreasing tick-host interactions with highly competent reservoirs (e.g., white-footed mice). Conversely, mesopredator presence might also amplify risk through increased tick abundance due to alternative reproductive hosts. We will employ a robust modeling framework combining multi-species occupancy models, joint-species distribution models, and ecological niche models. We will analyze mammal presence along urban-to-rural transects, incorporating environmental covariates to predict habitat suitability and species interactions. Tick density data and genetic testing for Borrelia burgdorferi informs our models on DIN variability. The modeling framework will be calibrated and cross-validated across the three cities to assess the consistency of mammal-mediated TBD risk patterns. By identifying mammal community motifs that either dilute or amplify LD risk, our findings aim to enhance landscape-scale disease management in urban environments.