Bridging landscape ecology and urban science to respond to the rising threat of mosquito-borne diseases

The rise of vector-borne diseases transmitted by the Aedes spp. mosquitoes is attributed, in part, to the dramatic rates of contemporary urbanization. Over the past 30 years, scientists have developed a wealth of knowledge around the drivers of heterogeneity in Aedes-borne disease risk within and between cities. However, in current Aedes-borne disease research, characterizations of “urban” are oversimplified, with the built environment and social institutions of the city often relegated to a background context. To mitigate the spread of Aedes-borne diseases, under the dual global pressures of urbanization and climate change, there is an urgent need to incorporate the multi-dimensionality of urban systems in driving Aedes-borne disease risk. This dissertation is anchored in socio-ecological sciences, and tailored to the complexities of urban eco-epidemiological dynamics. Herein, theory and methods from ecology, epidemiology, geography, and urban science are synthesized to develop and implement a novel urban systems approach for Aedes-borne diseases. T he first chapter establishes the theoretical foundation for this approach, integrating concepts from three bodies of knowledge: “cities as complex adaptive systems”, hierarchical patch systems theory, and relational geography. In the framework, cities are conceptualized as hierarchically-structured patches of different land uses and characteristics. Patch composition determines localized disease risk, while patch configuration and connectivity contribute to emergent patterns of disease risk and spread. Complexity is added to the system by considering the cross-scale and dynamical processes occurring within a city. Furthermore, the framework establishes how individual and collective social structures interact with the biophysical landscape to generate risk. The empirical research for this dissertation uses a range of data sets, from open source remotely-sensed environmental data and census-derived socio-economic data to fine-scale household survey and entomological data. Chapter 2 is carried out at the scale of the city, and examines how extreme climate and weather conditions in Colombia differentially affects the onset of peak dengue incidence for urban settlements with varying landscape and socio-economic properties. Using Bayesian spatio-temporal hierarchical models we discovered that extreme temperature anomalies (10–12°C) result in an earlier onset of dengue risk for high-elevation compared to low-elevation settlements, which experience increases in dengue risk two to four months after extreme temperature anomalies. Furthermore, the risk of dengue after extremely dry conditions is higher and extends for a longer duration in highly urban areas compared to areas with a low proportion of the population living in urban settlements. These findings indicate the potential for landscape-specific dengue early warning and forecasting frameworks. Chapter 3 is based in a mid-sized, rapidly growing city (Ibagué) embedded within the Andes Mountains of Colombia, and establishes homogenous urban typologies of dengue risk. Measuring dengue incidence across census block and higher order urban sections, we show that distinctive signatures of incidence can emerge from interactions between heterogeneous socio-environmental composition and configuration. Finally, Chapter 4 is carried out at the household and neighborhood scale in Ibagué, and examines how water governance and neighborhood-based social processes drive household-level dengue risk. We documented the role of collective societal memory of water scarcity in fostering a culture of water storage. We determined that neighborhood-based metrics of social cohesion do not necessarily translate to dengue household preventative practices and that to scale dengue prevention strategies, public health agencies may consider interventions rooted in “place-making” to foster linkages between perceived neighborhood-level versus household-level risk. This dissertation demonstrates how trans-disciplinary research bridges urban science, ecology, and public health research communities, and provides a pathway for mosquito-borne disease interventions to be incorporated into national-level early warning systems as well as community-based initiatives that collectively, set cities on more healthy and sustainable trajectories for the 21st century