The Effects of Water Storage and Meteorological Conditions on Enteric Infections from a Matched-Control Trial in Beira, Mozambique

Abstract

The provision of community-level piped drinking water infrastructure has the potential to reduce the burden of enteric diseases, including diarrhea, in rapidly growing urban centers. However, water intermittency and water storage practices, as well as impacts of meteorological conditions, may interfere with the progress made by drinking water interventions. Results from the PAASIM study, a matched-control trial assessing a piped water supply intervention in Beira, Mozambique, showed that provision of upgraded piped water infrastructure led to a reduction in water contamination and improvement in overall access to the water supply, but mixed evidence of health benefits from the drinking water supply upgrades. In this dissertation, I assessed the impact of water storage practices and meteorological conditions on enteric infection prevalence and the effectiveness of the PAASIM drinking water intervention. In Aim 1, I evaluated the impact of water contamination, at both the point of collection (PoC) and in water storage containers, on enteric pathogen infections using a causal mediation analysis approach. I found that households where contamination was detected in their PoC water had a 32% higher prevalence of stored water contamination and that both PoC and stored water contamination were associated with a higher prevalence of children’s enteric pathogen infections for some key pathogens of interest. Findings from Aim 1 demonstrate that reducing PoC water contamination and addressing water storage practices are important for mitigating waterborne disease risk in urban areas with piped water systems. In Aim 2, I assessed the variation in enteric infection prevalence across seasons and meteorological conditions. I found that enteric infections, particularly protozoal infections and co-infections, varied depending on seasonal conditions and rainfall events. Results from Aim 2 highlight the need to consider seasonal variation in environmental conditions and human behaviors in efforts to reduce the burden of enteric disease. In Aim 3, I assessed the impact of seasonality and meteorological conditions on the effectiveness of the PAASIM intervention for reducing enteric pathogen infections. I showed that season did not impact the effectiveness of the piped water intervention, but that it was more protective for several key enteric infections of interest following heavy rainfall events. Results from Aim 3 highlight the potential benefit of piped water interventions for providing resilience to seasonal changes in environmental conditions, as well as some additional protection following heavy rainfall events. Piped water infrastructure in urban settings may help mitigate health risks associated with extreme weather events and provide robust effectiveness in the presence of seasonal variation in enteric disease. However, water intermittency and water storage practice have the potential to impede the progress made by piped water interventions. Investments in urban settings should continue to prioritize providing robust, community-level piped water infrastructure to support growing populations but should also invest in strategies to reduce water intermittency and the need for water storage. Results from these analyses may be valuable for developing more resilient drinking water intervention strategies that can accommodate rapidly growing urban populations.