Impact of weather and season on stored water contamination and infant diarrhea in climate-vulnerable, urban Mozambique

Background: Diarrhea remains one of the leading causes of morbidity and mortality for children under the age of five, despite reductions in its overall global burden in recent decades. However, climate change, and its associated meteorological conditions - heavy rainfall, temperature, flooding - has the potential to impede or reverse progress that has been made toward alleviating the burden of diarrheal diseases. This is especially true in low-income, climate-vulnerable communities that are currently bearing many impacts of climate change. Better characterization of the impact of weather and season on drinking water quality and child health will allow us to capture the anticipated health burden associated with climate change. Methods: We characterized the associations of weather and season on infant diarrhea and household stored water quality in the city of Beira, Mozambique. We collected data from mother-child dyads in the third trimester of pregnancy and when the infant was 3-, 6-, 9-, and 12-months old. Using modified Poisson regression mixed effects models, we evaluated associations between weather (i.e. season, heavy rainfall events, ambient temperature, and flooding) and (1) household stored water quality and (2) infant diarrhea. Results: Rainy season (aPR: 1.49; 95% CI: [1.34, 1.67]) was associated with a higher prevalence of stored water contamination, and higher temperatures were associated with a higher prevalence of stored water contamination during the dry season only (aPR: 1.14; 95% CI: [1.03, 1.27]). Source water contamination was associated with a higher prevalence of stored water contamination during both rainy (aPR: 1.32; 95% CI: [1.11, 1.56]) and dry seasons (aPR: 1.56; 95% CI: [1.22, 2.00]). Rainy season (aPR: 1.18; 95% CI: [1.01, 1.38]) was associated with a higher prevalence of infant diarrhea, as was higher temperatures, though only during the dry season, (aPR: 1.19; 95% CI: [1.05, 1.35]). Conclusions: This study highlights the importance of addressing household water contamination for reducing the burden of diarrheal disease as well as the importance of understanding the seasonal and weather-dependent variation in both water contamination and infant diarrhea.