Assessing vulnerability to water-associated disease: an ecosystem approach to health

Abstract

Water-associated diseases are a significant cause of morbidity and mortality worldwide and are a barrier to sustainable development in many regions. Human pressures on the environment resulting in large-scale changes to land and water resources have been implicated in these health challenges. In this context, developing sustainable interventions requires a more integrative understanding of the complexity and relationships between these processes, as well as policy-relevant research that supports decision-makers. By applying a vulnerability framework to water-associated disease, this dissertation explored social and ecological determinants that mediate transmission at different scales. Vulnerability was conceptualized as the propensity of a system to be adversely impacted by a water-associated disease, described by dimensions of exposure, susceptibility and resilience. Based on this framework, a water-associated disease index (WADI) and mapping approach was developed, and applied to the case of dengue at a national level in Malaysia. The findings identified heterogeneous patterns of vulnerability, including regions experiencing consistently low and high vulnerability, as well as areas with changing conditions due to strong seasonal exposure. The WADI was further applied to assess the dynamic nature of vulnerability to water-associated disease in northeastern Brazil. Changes across the region due to short-term seasonal trends as well as long-term trends between time periods 2000 and 2010 were identified. These findings illustrated the importance of long-term global environmental changes such as land use intensification and growing urban population density, as well as short-term seasonal changes. In addition to the WADI analysis, qualitative research at a local level was conducted to investigate spatial perceptions of vulnerable places within a community. Findings illustrated different understanding of mosquito breeding sites among residents in the study areas, suggesting potential differences in susceptibility to dengue despite similar levels of exposure on a large scale. Overall, this dissertation highlights the need for a comprehensive understanding of vulnerability to water-associated disease, achieved by considering complex spatiotemporal relationships as well as local perspectives.