Influence of temperature and precipitation on the effectiveness of water, sanitation, and handwashing interventions against childhood diarrheal disease in rural Bangladesh: a re-analysis of a randomized control trial

Abstract

Background: Climate change may influence the effectiveness of environmental interventions. We investigated if climate and environment modified the effect of low-cost, point-of-use water, sanitation, and handwashing (WASH) interventions on diarrhea and predicted intervention effectiveness under climate change scenarios. Methods: We analyzed data from a cluster-randomized trial in rural Bangladesh that measured diarrhea prevalence in children 0-2 years from 2012-2016. We matched remote sensing data on temperature, precipitation, humidity, and surface water to households by location and measurement date. We estimated prevalence ratios (PR) for WASH interventions vs. control stratified by environmental factors using generative additive models and targeted maximum likelihood estimation. We estimated intervention effects under predicted precipitation in the study region in 2050 for climate change scenarios from different Shared Socioeconomic Pathways (SSPs). Findings: WASH interventions more effectively prevented diarrhea under higher levels of total precipitation in the previous week and when there was heavy rain in the previous week (heavy rainfall PR = 0.38, 95% CI 0.23-0.62 vs. no heavy rainfall PR = 0.77, 0.60-0.98). We did not detect substantial effect modification by other environmental variables. WASH intervention effectiveness increased under most climate change scenarios; in a fossil-fueled development scenario (SSP5), the PR was 0.46 (0.44-0.48) compared to 0.67 (0.65-0.68) in the study. Interpretation: WASH interventions had the strongest effect on diarrhea under higher precipitation, and effectiveness may increase under climate change without sustainable development. WASH interventions may improve population resilience to climate-related health risks. Funding: Bill & Melinda Gates Foundation, National Institute of Allergy and Infectious Diseases, National Heart, Lung, And Blood Institute

Rainfall and Temperature Influences on Childhood Diarrhea and the Effect Modification Role of Water and Sanitation Conditions: A Systematic Review and Meta-Analysis

“…This is consistent with the finding of the study that shows that when mean temperature and rainfall increase, households using unimproved sanitation or unimproved water have more cases of diarrhea [43]. On the other hand, the interventional study reported that when there were co-occurrence shifts in temperature and precipitation, the prevalence of childhood diarrhea increased by half in areas with unimproved WASH [72].…”

Influence of climatic and environmental risk factors on child diarrhea and enteropathogen infection and predictions under climate change in rural Bangladesh

“…We restricted diarrhea analyses to the control arms of the original trial (N=7,320 measurements) because a companion analysis found that intervention effects on diarrhea were modified by climate and environment. 24 For pathogen carriage outcomes, we pooled across all study arms in which specimens were collected (N=1,408 measurements) and included study arm as a covariate.…”