The major goal of this project is to analyze baseline data on and samples from a community that will soon undergo transformative neighborhood level sanitation infrastructure improvements. The study team is leveraging preliminary funding to collect data and samples in 2024, but funding for sample analysis is not available. Infrastructure improvements in Quelimane, Mozambique a cholera-endemic city of 420,000, will be transformative, as ~20% of people in the city currently practice open defecation. We will leverage this imminent major infrastructure project – funded by the World Bank and serving 200,000 people – to assess its impacts on child health, disease transmission, and climate resilience, toward a better understanding of the cost-benefit of such investments. Safe sanitation is considered one of the greatest public health achievements of the 20th Century, but three billion people still lack improved sanitation infrastructure. Pathogens in fecal wastes reach the environment through well-understood pathways, yet evidence for the impact of city-wide sanitation in low- income urban settings is largely uncharacterized. Rigorous controlled studies of city-wide interventions are difficult to carry out, as it is often infeasible to randomize and challenging to find opportunities to collect preliminary data immediately before implementation of a project. This unique opportunity will allow us to overcome many of these challenges by collecting and analyzing baseline data prior to initiation of construction of the neighborhood wide sanitation intervention. We will map the urban, informal neighborhoods in the city and collect baseline data on demographic information, water and sanitation access, and household conditions and behaviors to establish a robust baseline for young children in future intervention and matched comparison areas. In a subset of 200 households, we will collect household environmental samples including domestic soils and synanthropic flies (SA1) and in 600 households we will also measure anthropometry and collect biological samples from children from one month to five years of age to measure baseline markers of child health and development (SA2). We propose to analyze environmental and stool samples for enteropathogens using state-of-the-art molecular methods (SA1 + SA2). This transformational sanitation intervention is a unique, natural experiment that will allow our team to characterize the living conditions, exposure risks, and infection rates of children living in low-income neighborhoods in Quelimane, to establish a robust baseline for future impact analyses, while also understanding the relationship between these factors under current conditions. Our multidisciplinary research team has decades of experience conducting field studies of enteric diseases and impact evaluations of water and sanitation interventions in low-income settings, and specifically in Mozambique. This work elucidating the potential health impacts of community-sanitation interventions in Quelimane will serve as a model for other highly urbanizing, coastal tropical or subtropical cities with high vulnerability to climate and extreme weather globally.

PROJECT NARRATIVE Our research team has a unique opportunity to assess the impact of a transformative neighborhood level sanitation improvement intervention – the World Bank-funded Mozambique Urban Sanitation Project – construction on which will be completed in the city of Quelimane, Mozambique by December 2026. The goal of this study is to analyze previously collected baseline data and samples that will serve as critical preliminary data to enable a future evaluation of how the neighborhood wide sanitation improvements impact environmental contamination and acute and long-term child health outcomes. We will analyze current associations between living conditions, exposure risks, and infection rates of the population living in low-income neighborhoods in Quelimane; assess balance between intervention and comparison groups; and analyze samples using state-of- the-art molecular assays.