Spatial configuration and the Dilution Effect in Vector-Borne Diseases: Insights from Agent-Based Model

Biodiversity provides ecosystem services, including health protection by reducing infection risks through the "dilution effect." This mechanism occurs when vertebrate diversity decreases disease prevalence in host populations. Prior SIR (Susceptible-Infected-Recovery) models have explored the dilution effect, but incorporating spatial configuration remains a challenge. We simulated the distances that agents (vectors and hosts) could travel under different movement types. We assessed maximum prevalence ((infected agents/total population) × 100) in each simulation using four Agent-Based Models (ABMs) implemented in NetLogo. These models tested scenarios with and without susceptibility diversity, combined with different agent densities (0.25 to 2) and movement distances. Our findings indicate that movement type has minimal relevance to the dilution effect. However, movement distance significantly influences disease prevalence. Notably, the dilution effect counteracts density-dependent effects on infectious disease prevalence. This study highlights the importance of susceptibility diversity in host communities for the effectiveness of the dilution effect, while vector susceptibility diversity plays a minor role. We identified movement and distance as key parameters influencing the dilution effect, which had not been analyzed before. Future studies should consider movement distance when evaluating the impact of spatial configuration on disease transmission. Our results provide new insights into the complex dynamics of infectious disease prevalence across spatial configurations and ecological settings.