Effects of an urban sanitation intervention on childhood enteric infection and diarrhea in Maputo, Mozambique: a controlled before-and-after trial

Abstract

Background. Onsite sanitation serves more than 740 million people in urban areas, primarily in low-income countries. Although this critical infrastructure may play an important role in controlling enteric infections in high-burden settings, its health impacts have never been evaluated in a controlled trial. Methods. We conducted a controlled before and after trial to evaluate the impact an onsite urban sanitation intervention on the prevalence of bacterial and protozoan infection (primary outcome), soil transmitted helminth (STH) re-infection, and seven-day period prevalence of diarrhoea among children living in informal neighborhoods of Maputo, Mozambique. A non-governmental organization replaced existing shared latrines in poor condition with engineered pour-flush toilets with septic tanks serving household clusters. We enrolled children aged 1-48 months at baseline and measured outcomes before the intervention and at 12 and 24 months following intervention. We measured outcomes concurrently among children served by the sanitation improvements and those in a comparable control arm served by existing poor sanitation. The trial was registered at ClinicalTrials.gov, number NCT02362932. Findings. At baseline, we enrolled 454 children from 208 intervention clusters and 533 children from 287 control clusters. We enrolled or re-visited 462 intervention and 477 control children 12 months 60 after intervention and 502 intervention and 499 control children 24 months after intervention. Despite nearly exclusive use of the intervention, we found no evidence that engineered onsite sanitation affected the overall prevalence of any measured bacterial or protozoan infection (12-month adjusted prevalence ratio 1.05, 95% CI [0.95-1.16]; 24-month adjusted prevalence ratio 0.99, 95% CI [0.91-1.09]), any STH re-infection (1.11 [0.89-1.38]; 0.95 [0.77-1.17]), or diarrhoea (1.69 [0.89-3.21]; 0.84 [0.47-1.51]) after 12 or 24 months of exposure. Among children born into study sites after the intervention and measured at the 24-month visit, we observed a reduced prevalence of any STH re-infection of 49% (adjusted prevalence ratio 0.51 [95% confidence interval 0.27 - 0.95]), Trichuris of 76% (0.24 [0.10 - 0.60]), and Shigella infection by 51% (0.49 [0.28-0.85]) relative to the same age group at baseline. Interpretation. The intervention did not reduce the overall prevalence of enteric infection and diarrhoea among all enrolled children but may have substantially reduced the prevalence of STHs and Shigella among children born into clusters with sanitary improvements.

Quantitative Microbial Risk Assessment of Pediatric Infections Attributable to Ingestion of Fecally Contaminated Domestic Soils in Low-Income Urban Maputo, Mozambique

“…When comprehensive interventions are not possible, efforts targeting either source or contact control are necessary to progress toward the drastic reduction in dose, which our model indicates is needed to achieve acceptable levels of risk. Although rigorous trials of sanitation infrastructure found that effective source control may be a distant prospect in LMICs, 7 − 12 , 42 contact control, while insufficient, may be important in the near-term to reduce infection risks.…”

How does sanitation influence people's quality of life? Qualitative research in low-income areas of Maputo, Mozambique

“…This study was linked to the Maputo Sanitation trial (MapSan), which evaluated an urban shared sanitation intervention ( clinicaltrials.gov registration: NCT02362932) ( Knee et al, 2020 ). We used the trial as a vehicle, but our study is not an evaluation of the intervention.…”

Impacts of an urban sanitation intervention on fecal indicators and the prevalence of human fecal contamination in Mozambique

“…The intervention impact on fecal contamination was evaluated using a controlled before-and-after (CBA) study design. 5,43 Children in each intervention compound were enrolled immediately before the new latrine was opened for use, with concurrent enrollment of control compounds conducted at a similar frequency. Follow-up visits to each compound were conducted approximately 12 months following baseline enrollment.…”

“…2–4 Recent evaluations of a range of WASH interventions found inconsistent and largely negligible impacts on child diarrhea, growth, and enteric infection. 5–12 Notably, combined interventions did not provide greater protection than their constituent interventions alone, suggesting that key sources of pathogens and pathways of exposure are inadequately addressed by conventional WASH strategies. 6,7,9,13–15…”