Impact of Immature Tick Activity Synchrony on Tick Population Dynamics, Borrelia burgdorferi Infection Prevalence, and Spatial Spread of Lyme Disease

The northward expansion of Lyme disease in North America poses a major public health concern, with migratory birds acting as key vectors of Borrelia burgdorferi. Focusing on the seasonal activity synchrony between larvae and nymphs of Ixodes scapularis, this study developed a multi-species patch-based mathematical model to investigate its effects on tick population dynamics, infection prevalence, and spatial spread. Simulation results show that moderate synchrony between larval and nymphal activity maximizes the proportion of infected nymphs, whereas complete asynchrony favors the maximization of tick population size. Activity synchrony also accelerates pathogen colonization in newly invaded regions. Sensitivity analysis confirms that activity synchrony is the most critical factor influencing local tick infection prevalence and population size. The findings of this study provide strong theoretical support for elucidating the transmission characteristics of Lyme disease and establishing regionally targeted precision prevention and control systems.