A controlled, before-and-after trial of an urban sanitation intervention to reduce enteric infections in children: research protocol for the Maputo Sanitation (MapSan) study, Mozambique

Abstract

IntroductionAccess to safe sanitation in low-income, informal settlements of Sub-Saharan Africa has not significantly improved since 1990. The combination of a high faecal-related disease burden and inadequate infrastructure suggests that investment in expanding sanitation access in densely populated urban slums can yield important public health gains. No rigorous, controlled intervention studies have evaluated the health effects of decentralised (non-sewerage) sanitation in an informal urban setting, despite the role that such technologies will likely play in scaling up access.Methods and analysisWe have designed a controlled, before-and-after (CBA) trial to estimate the health impacts of an urban sanitation intervention in informal neighbourhoods of Maputo, Mozambique, including an assessment of whether exposures and health outcomes vary by localised population density. The intervention consists of private pour-flush latrines (to septic tank) shared by multiple households in compounds or household clusters. We will measure objective health outcomes in approximately 760 children (380 children with household access to interventions, 380 matched controls using existing shared private latrines in poor sanitary conditions), at 2 time points: immediately before the intervention and at follow-up after 12 months. The primary outcome is combined prevalence of selected enteric infections among children under 5 years of age. Secondary outcome measures include soil-transmitted helminth (STH) reinfection in children following baseline deworming and prevalence of reported diarrhoeal disease. We will use exposure assessment, faecal source tracking, and microbial transmission modelling to examine whether and how routes of exposure for diarrhoeagenic pathogens and STHs change following introduction of effective sanitation.EthicsStudy protocols have been reviewed and approved by human subjects review boards at the London School of Hygiene and Tropical Medicine, the Georgia Institute of Technology, the University of North Carolina at Chapel Hill, and the Ministry of Health, Republic of Mozambique.Trial registration numberNCT02362932.

Household sanitation is associated with lower risk of bacterial and protozoal enteric infections, but not viral infections and diarrhoea, in a cohort study in a low‐income urban neighbourhood in Vellore, India

“…Further, recent evidence from multiple studies suggests that controlling enteric infection, even at subclinical levels, is important for longer‐term health outcomes . Considering the large proportion of diarrhoea associated with viral pathogens in this study, these findings provide evidence to support future sanitation studies excluding viral pathogens or diarrhoeal episodes from primary outcome measures, and instead focusing on enteric infections by bacterial and protozoal agents, which may be more likely to be impacted by interventions to reduce exposure to faecal contamination in the environment .…”

“…and heat‐stable enterotoxin‐producing E. coli (ST‐ETEC) . Most other enteric organisms, including many bacteria, were at most moderately associated with diarrhoea, suggesting that human health responses to environmental conditions may be more accurately detected by measurement of enteric organisms in stool . Further, recent evidence from multiple studies suggests that controlling enteric infection, even at subclinical levels, is important for longer‐term health outcomes .…”

“…Mitigation of paediatric enteric infection by household sanitation may have important implications for malnutrition, growth and cognitive development, independent of diarrhoea . While the mechanisms of association have been proposed and examined in cross‐sectional studies, there are several ongoing and recently completed randomised and controlled before‐and‐after studies examining these impacts that will improve understanding of the environmental and biological mechanisms involved . Given the reliability and relative feasibility of molecular methods, including parallel and multiplex assays like the TaqMan Array Card and Luminex xTAG ® system, future sanitation studies should consider measures of enteric organisms present in stool to better understand how changes to the immediate household environment cause changes in faecal exposures and infection .…”

Assessment of Fecal Exposure Pathways in Low-Income Urban Neighborhoods in Accra, Ghana: Rationale, Design, Methods, and Key Findings of the SaniPath Study

“…This gap between risk assessment and epidemiology becomes even more relevant as additional health outcomes associated with fecal exposure (e.g., environmental enteropathy, stunting, and cognitive deficits) are being recognized. 35,36 In this context, not only short-term exposure may be relevant, but cumulative exposure over extended periods is also important, similar to considering the risks posed by chronic exposure to toxic substances or ionizing radiation.…”

Investigating the differential impact of school and community-based integrated control programmes for soil-transmitted helminths in Timor-Leste: the (S)WASH-D for Worms pilot study protocol

“…Intervention studies examining the impact of one or more components of WASH on STH infections have been conducted, or are currently underway, both in schools [32–36] and in communities [46–49]; however, the relative merits of the two delivery strategies have not been discussed in the literature. Furthermore, to our knowledge, there are no studies which have directly compared school-based and community-based integrated WASH and deworming programmes.…”