Mobility and non-household environments: Understanding dengue transmission patterns in urban contexts

Households (HH) have been traditionally described as the main environments where people are at risk of dengue and other arbovirus infections. Mounting entomological evidence suggests a larger role for environments other than HH. Recently, an agent-based model (ABM) estimated that over half of infections occur in non-household (NH) environments such as workplaces, markets, and recreational sites. Despite the inferred importance of NH sites, we do not yet know how their urban spatial configurations, and human and vector mobility between them, affects their role in dengue transmission. To address this gap, we expanded an ABM calibrated with field data from Kenya to examine movement of people and vectors under different spatial configurations of buildings. We assessed the number of people traveling between HH and NH and the distances traveled, in three urban configurations: NH distributed randomly (scattered), concentrated in a single center, or clustered in multiple centers. Across simulations, the number of people moving was the most influential variable, with higher movement between HH and NH increasing case numbers. The number of cases was also higher when NH were scattered compared to centered or clustered. Intriguingly, the distance people traveled from HH to NH had little effect on dengue burden but influenced the spatial clustering of infections. These findings underscore the role of NH as major spreaders of infections between HH and NH environments, and the importance of human movement in driving dengue dynamics.