Socio-Ecological Complexity and the Control of Helminthic Neglected Tropical Diseases

Soil-transmitted helminthiases (STH) and schistosomiasis are helminthic Neglected Tropical Diseases (NTDs) which currently infect 1.5 billion and 190,000 individuals, respectively, and cause substantial morbidity. Global control programs have been established to alleviate this burden through mass drug administration, marketed as a cost-effective solution with the potential to additionally alleviate poverty. While these control programs have achieved success, helminthic NTDs and poverty continue to persist in the global South. There is rising concern as to whether a narrow, biomedical intervention can sustainably control diseases which exhibit characteristics of socio-ecological complexity. While studies have addressed the social and ecological determinants of helminthic NTDs, such analyses are often fragmented in nature and these factors remain largely overlooked by policymakers. Conceptual frameworks which allow for the integrated consideration of diverse socio-ecological determinants are needed to re-conceptualize our understanding of helminthic NTDs and to guide both quantitative analysis and control strategies. Finally, while governance studies have highlighted the importance of accounting for socio-ecological complexity in effectively managing problems exhibiting such characteristics, this complexity is largely ignored by current control programs.

The overall aim of this dissertation is to apply a socio-ecological lens to comprehensively improve our understanding of helminthic NTDs and provide evidence-based policy recommendations to achieve sustainable helminthic NTD control. First, the socio-ecological complexity underlying helminthic NTD transmission is investigated through meta-analyses of helminth polyparasitism, a review of social determinants associated with polyparasitism, and an empirical field study quantifying the socio-ecological determinants of persistent schistosomiasis. Following the establishment of socio-ecological complexity, a vulnerability framework which accounts for the diverse socio-ecological determinants of STH infections is derived. This framework is subsequently used to guide the construction of a spatially-explicit vulnerability index for STH infections in sub-Saharan Africa. Finally, the thesis guides the design and management of helminthic NTD control programs at the micro-level through the evaluation of a village governance model designed to account for socio-ecological complexity as an alternative to the current governance of NTD control programs. The thesis concludes by forecasting the vulnerability of communities in sub-Saharan Africa to STH infections in 2050 to provide policy prescriptions at the macro-level.

Overall, this work demonstrates the importance of accounting for socio-ecological complexity in understanding helminthic NTD transmission and sustainably controlling helminthic NTDs. While this work was limited by publicly available data which may be insufficient in accurately capturing socio-ecological determinants, our findings highlight the need to continue developing frameworks, integrating diverse sources of data, and conducting quantitative analysis to contribute to the growing evidence base establishing the importance of socio-ecological complexity. Future work incorporating additional mixed-methods approaches to integrate natural and social science disciplines has the potential to further improve our understanding of socio-ecological complexity and ultimately lead to the sustainable control of helminthic NTDs.