Exploring disaster-related disease outbreaks and the impact of pre-existing vulnerabilities: focusing on cholera and Africa
Creators: name: Charnley, Georgina Eva Ceres
Publisher: name: Imperial College London
Year: 2022

description: Research into the links between infectious disease outbreaks and disasters has increased over time, with continued discussion regarding the rate and mechanisms for these links. Yet, significant discrepancies and research gaps remain globally in terms of the frequency, geography and characteristics of post-disaster disease outbreaks. Here, the aim was to address these gaps and discrepancies by exploring several disasters and their associated risk factors and further quantifying their impact. By increasing this understanding, this improves the extent to which disaster-related disease outbreaks can be prepared for, to prevent outbreaks from exacerbating and prolonging disaster recovery. To further understand these risk factors, disease outbreaks in drought and conflict settings were analysed and an overview of the research area was gained through the first global systematic review of the literature. Cholera was selected as a focus for the research here, due to it being a disease of global public health importance and potentially linked to drought and conflict. The area of study was predominately Africa (due to the relatively high cholera, conflict and drought burden) and was studied at several spatial scales, from national to administrative level 1. The research identified many important risk factors for cholera outbreaks in a disaster context. To help further identify areas for prioritisation both nationally and sub-nationally, drought-related cholera outbreaks were investigated, as droughts are a relatively understudied natural hazard. Generalised linear models were used to identify a potential relationship and the flexibility of the modelling approach allowed for multiple covariates to be tested. The lack of available water during a drought exacerbates risk factors relating to cholera transmission. However, increasing freshwater availability, improving access to sanitation, poverty elimination and emissions reductions could help to offset cholera risk in the future. Using random forest models, specific targets for these risk factors were further quantified for Nigeria. States with Multi Dimensional Poverty Index values over 0.38 and sanitation access below 54% were particularly at risk for cholera transmission, which includes most northern states in Nigeria. Conflict-related cholera outbreaks were analysed by applying the self-controlled case series in a new application. The modelling approach uses conditional logistic regression to understand the impact of an exposure (conflict) on an event (outbreak). Conflict had the most significant impact on cholera in the first week after the conflict and increased the risk of cholera outbreaks by as much as 3.6 times. The recently developed percentage attributable fraction equations were applied to these results and identified &lt;20% of cholera outbreaks being attributable to conflict in Nigeria and the Democratic Republic of Congo (DRC). The research helped quantify a specific health effect of both the Boko Haram conflict in Nigeria and the civil unrest in eastern DRC. Disease, disasters and global change were brought together here beyond what has previously been done and the knowledge gained was applied to policy throughout. Furthermore, a variety of projections and scenarios were used to identify how potential future conditions could alter cholera transmission. The Global Task for Cholera Control have ambitious 2030 targets, that will be essential for global cholera eradication and are important to make sure governments are committed to overcoming challenges. Both disasters and cholera outbreaks are not new phenomenon and societies have always had to respond and adapt but marked differences in global inequity can prevent this. Giving people agency and empowerment to react to sudden changes and make informed decisions to protect their health will require long-term investment in sustainable development. Enhancing development has far-reaching impacts and is essential for controlling disease, both regionally and globally.