Urban heterogeneities and pathogen transmission
Urban populations are growing rapidly and cities are larger than ever before. Urban areas contain staggering levels of demographic and socioeconomic variation. In particular, heterogeneities in density, wealth and access to resources produce variability in susceptibility, transmission and recovery, which drive local disease dynamics and impact the efficacy of control. Unfortunately, these important heterogeneities are often overlooked; infectious disease data and intervention strategies frequently aggregate across the epidemiologically important heterogeneities in urban areas, in many cases treating cities as single units. Measuring urban heterogeneities can vastly improve urban disease surveillance, prediction, and control strategies.
We describe heterogeneities and changes in population density across space and time in four urban disease systems with different routes of transmission using various methodologies. Using a series of case studies, we describe how disaggregating epidemiologically important demographic characteristics within urban populations improved our understanding of local disease dynamics and our abilities to implement control. We also discuss how improved control in cities could resonate to rural areas, in some cases breaking transmission maintained through urban-rural source sink dynamics. Characterizing demographic heterogeneities within cities will be a significant step forward in the control of infectious diseases.