Seasonality in multi-host disease systems

Demographic processes have long been known to critically impact population-level epidemic dynamics. Within a single ecosystem, a novel pathogen may circulate among multiple species, each with different seasonal demographic patterns. We investigate the synergy between these different seasonal demographic processes and epidemic dynamics in a two-host disease system. While differences in disease burden between hosts are often explained by immunological differences, behavior, or social contact structures, we find that different demographic patterns alone can also drive differences in disease burden over time, even with only two host species. Most importantly, we show how the timing of disease introduction relative to annual birth cycles in one species can profoundly, and potentially unpredictably or unexpectedly, influence disease dynamics in both host species.