Associations Between Point-of-Use Water Treatment Interventions and Cognitive Scores among Children 5 Years of Age and Younger in Limpopo, South Africa

For children in low-resource settings, repeated exposure to enteric pathogens, including through unsafe water, can have long-term effects and is potentially associated with impaired cognitive development. Access to effective, low-cost point-of-use (POU) water treatment technologies may therefore improve cognitive function. A community-based randomized controlled trial of two POU water treatment technologies was conducted in rural Limpopo, South Africa. In total, 404 households with a primary study child younger than 3 years were randomly assigned to one of four groups: 1) a silver-impregnated ceramic filter and a silver-impregnated ceramic tablet group, 2) a silver-impregnated ceramic tablet only group, 3) a safe-storage water container group, or 4) a no-intervention group. Follow-up surveys were conducted every quarter for the following 2 years. Approximately 2 years after the baseline assessment, 236 of the primary study children were evaluated using the Wechsler Preschool and Primary Scale of Intelligence, Third Edition (WPPSI-III) examination to estimate the effects of the water treatment technologies on cognitive function. There was no significant difference found in WPPSI-III composite scores between intervention groups, and the individual presence of enteric pathogens at enrollment, reported diarrhea, and water service level exhibited no associations with WPPSI-III scores after controlling for covariates. However, several sociodemographic variables were significant predictors of cognitive function within the study population. These results are consistent with the lack of significant effects of the interventions on more proximal outcomes, such as enteric infections, diarrhea, and growth stunting, for the same study population, despite significant improvements in microbial water quality.