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

Key environmental exposure pathways to antimicrobial resistant bacteria in southern Malawi: A SaniPath approach

Antimicrobial resistance (AMR) poses a severe global health threat, yet the transmission pathways of AMR within communal public environments, where humans and animals interact, remain poorly explored. This study investigated AMR risk pathways, prevalence, and seasonality of extended-spectrum β-lactamase (ESBL) producing E. coli and K. pneumoniae, and observed practices contributing to environmental contamination within urban, peri-urban, and rural Malawi. Using the SaniPath tool, in August 2020, transect walks across three Malawian study sites identified potential AMR exposure pathways, including drains, standing water, soil, and areas of communal hand contact. Subsequently, from September-2020 to August-2021, 1440 environmental samples were collected at critical points along exposure routes (n = 40/month from each site). These underwent microbiological analysis using chromogenic agar techniques to detect the presence of ESBL E. coli and ESBL K. pneumoniae. Results showed the highest ESBL prevalence in urban environments (68.1 %, 95%CI = 0.64-0.72, p < 0.001) with a higher ESBL presence seen in drains (58.8 %, 95%CI = 055-0.62, p < 0.001) and soil (54.1 %, 95%CI = 0.46-0.62, p < 0.001) compared to other pathways. Environmental contamination was attributed to unavailability and poor condition of sanitation and hygiene infrastructure based on key informant interviews with community leaders (n = 9) and confirmed by independent observation. ESBL prevalence varied between seasons (χ2 (2,N = 1440) = 10.89, p = 0.004), with the highest in the hot-dry period (55.8 % (n = 201)). Prevalence also increased with increased rainfall (for ESBL E.coli). We highlight that community environments are likely to be a crucial component in AMR transmission, evident in the abundance of ESBL bacteria in identified exposure pathways. Additionally, poor sanitation infrastructure and practices coupled with seasonal dynamics further affect the presence of ESBLs in communal environments. Therefore, a context appropriate whole system approach that tackles infrastructure and behavioural factors, supported by effective surveillance is required to impact AMR and a range of aligned development challenges in these settings.

Exposure behaviour to Escherichia coli among households in Imvepi refugee settlement, Terego district Uganda

INTRODUCTION

Exposure to Escherichia coli (E. coli) is a risk factor for diarrhoeal diseases, which pose a significant problem in refugee settlements. Refugee populations are exposed to faecal microorganisms through multiple pathways including sub-optimal sanitary facilities, contaminated drinking water, produce and food, flood water, bathing water, and soil among others. While these pathways are well-documented, specific exposure behaviours remain underexplored. We assessed exposure behaviour to E. coli among households in Imvepi refugee settlement, Uganda, and provided evidence-based recommendations for the design of interventions to reduce excreta-related disease in refugee settlements.

METHODS

Guided by the Sanitation Safety Planning approach, we surveyed 426 households in Imvepi refugee settlement, Uganda, using a digitized questionnaire and an observation checklist. We collected data on the background characteristics and exposure behaviour of women and emancipated girls (minors living on their own, having borne a child, married, or pregnant). The outcome variable, E. coli exposure behaviour, was measured using a five-point Likert scale, assessing behaviours that increase the risk of exposure. Data were cleaned in Microsoft Excel and analyzed in Stata version 17. Descriptive statistics were performed to summarize the data. We used modified Poisson regression to determine the factors associated with the outcome.

RESULTS

Over 59.4% (253) exhibited high-risk exposure behaviour. Residing in compound homes (Adjusted Prevalence Ratio (APR) = 0.72, 95% Confidence interval (CI): 0.58-0.90), being aged 35-49 years (APR = 0.76, 95% CI: 0.60-0.97), having household heads with post-primary education (APR = 0.54, 95% CI: 0.38-0.77), high knowledge (APR = 0.69, 95% CI: 0.59-0.80), and high-risk perceptions regarding exposure to E. coli (APR = 0.75, 95% CI: 0.64-0.88) were associated with a lower prevalence of high-risk E. coli exposure behaviours. Conversely, having sanitary facilities with excreta overflowing from the squat hole (APR = 1.26, 95% CI: 1.08-1.48) was associated with a higher prevalence of high-risk exposure behaviours.

CONCLUSION

The study indicates a substantial prevalence of high-risk E. coli exposure behaviours in the refugee settlement.. There's a need to implement behaviour change interventions targeted at preventing or minimizing exposure, especially among households whose heads have low education attainment, those with young caretakers and those with limited knowledge and low-risk perceptions regarding exposure to E. coli.

Indicators to complement global monitoring of safely managed on-site sanitation to understand health risks

Halfway through the Sustainable Development Goal (SDG) period, there has been little research on the criteria for monitoring safely managed sanitation under SDG target 6.2. For reporting against SDGs, global indicators are necessarily limited and exclude many safety aspects from a public health perspective. Primary survey data from 31,784 households in seven countries in Asia and Africa were analysed, comparing estimates of safely managed on-site sanitation based on global indicators with five complementary indicators of safety: animal access to excreta, groundwater contamination, overdue emptying, entering containments to empty and inadequate protection during emptying. Application of additional criteria reduced the population with safely managed sanitation by 0.4-35% for specific indicators, with the largest impact due to the risk of groundwater contamination, animal access, and containments overdue for emptying. Combining these indicators across the service chain, excluding transport and treatment, found almost three-quarters of on-site systems currently assessed as safely managed with global indicators were considered unsafe based on complementary indicators. A more comprehensive assessment of safety of on-site sanitation can be achieved through these indicators, which could be integrated into national monitoring systems and used to inform sanitation investments that address local health-related risks.

The Impact of Rapid Handpump Repairs on Diarrhea Morbidity in Children: Cross-Sectional Study in Kwale County, Kenya

BACKGROUND

Handpumps are used by millions of people as their main source of water. Although handpumps represent only a basic form of water provision, there have been continuous efforts to improve the performance of these systems as they are likely to remain in use for many years to come. The introduction of a professional maintenance service in southern Kenya has shown an order of magnitude improvement in operational performance over community-based management, with 90% of handpump faults repaired within 3 days of being reported. One driver behind these efforts is the assumption that a more reliable water supply will lead to a reduction in water-related disease. However, it is not clear if operational improvements lead to health gains. Despite limited empirical evidence, some modeling studies suggest that even short periods of drinking contaminated water can lead to disproportionate negative health impacts.

OBJECTIVE

The aim of this study was to assess whether the improvements in operational performance from the rapid professional maintenance of rural handpumps lead to improved household health outcomes.

METHODS

From a sample of households using handpumps as their primary water source in Kwale County, Kenya, we measured the 2-week prevalence of World Health Organization-defined diarrhea in children, reported by the adult respondent for each household. We compared the rates before and after a period during which the households' handpumps were being professionally maintained. We then conducted a cross-sectional analysis, fitting logistic regression models with reported diarrhea as the dependent variable and speed of repair as the independent exposure of interest, adjusting for household socioeconomic characteristics; dwelling construction; and Water, Sanitation, and Hygiene (WASH)-related factors. We fitted an additional model to examine select interactions between covariates.

RESULTS

Reported diarrhea in children was lower in households whose pumps had been repaired within 24 hours (adjusted odds ratio 0.35, 95% CI 0.24-0.51). This effect was robust to the inclusion of multiple categories of covariates. No reduction was seen in households whose pump repairs took more than 24 hours. Analysis of interaction terms showed that certain interventions associated with improved WASH outcomes were only associated with reductions in diarrhea in conjunction with socioeconomic improvements.

CONCLUSIONS

Only pump repairs consistently made within 24 hours of failure led to a reduction in diarrhea in the children of families using handpumps. While the efficacy of reduction in diarrhea is substantial, the operational challenges of guaranteeing same-day repairs limits the effectiveness of even best-in-class pump maintenance. Maintenance regimes that cannot bring handpump downtimes close to zero will struggle to generate health benefits. Other factors that reduce diarrhea prevalence have limited effect in isolation, suggesting that WASH interventions will be more effective when undertaken as part of more holistic poverty-reduction efforts.

Conceptualization of the Transmission Dynamic of Faecal-Orally Transmitted Diseases in Urban Exposome of Sub-Saharan Africa

In sub-Saharan Africa, many urban dwellers are at risk of faecal-orally transmitted diseases due to unplanned and growing urbanization with inadequate sanitation. Making it essential to understand the urban transmission of these diseases and the associated responses. This perspective paper discussed an approach to design a diagram of transmission dynamic from a combination of an urban exposome framework and transmission of faecal-oral diseases. The result is an exposome diagram displaying the interconnection of exposure components and potential barriers to stop the transmission of faecal-oral diseases in the urban area subdivided into public, domestic and individual. As an exposome diagram, it helps to follow the dynamics of exposure over time and to plan targeted surveillance and intervention.

Animal contact and paediatric acute febrile illness in Greater Accra Region, Ghana

Objective

To examine the association between animal contact (primarily dogs and cats) and non-malarial fever, as well as with secondary symptoms of headache, nausea, vomiting, and cough, in 687 children in Greater Accra Region, Ghana.

Design

Cross-sectional study of acute febrile illness among children aged 1-15 years old between October 2016 and August 2017.

Setting

Ledzokuku-Krowor Municipal Assembly (LEKMA) Hospital, Teshie, Greater Accra Region.

Participants

The study included children with acute fever, defined as a measured temperature of greater than 37.5°C, occurring less than seven days before the hospital visit, and afebrile children as controls.

Main outcome measures

Measured fever, self-reported fever, and secondary symptoms, each adjusting for patient household characteristics.

Results

Animal contact was neither associated with measured fever (OR = 1.04, 95% CI 0.73-1.49) nor with self-reported fever (OR = 0.97, 95% CI 0.68-1.39). Animal contact was associated with headache (OR = 3.26, 95% CI 2.23-4.77, P < .01) and nausea (OR = 3.05, 95% CI 1.99-4.68, P < .01), but not with vomiting or cough. Additional models that used alternate inclusion criteria to define non-malarial fever yielded similar results. Several bacterial zoonoses that could plausibly have been transmitted by dogs and cats were diagnosed in the study population.

Conclusion

These findings suggest the need for future studies to evaluate animal contact as a risk factor for bacterial zoonoses that may serve as an etiological driver of acute febrile illness.

Funding

no external funding.

Expected annual probability of infection: A flood-risk approach to waterborne infectious diseases

This study introduces a new approach for the investigation of infections after an accidental ingestion of contaminated floodwater. The concept of Expected Annual Probability of Infection (EAPI) is introduced and implemented in an infection risk-model approach, by combining a Quantitative Microbial Risk Assessment (QMRA) with the four steps in flood risk assessment. Two groups and exposure paths are considered: adults wading in floodwater and small children swimming/playing in floodwater. The study area is located in Ghana, West Africa. Even though Ghana is one of the most urbanized countries in Africa it has significant problems with water resources management and public health. While cholera is classified as endemic in Accra, the natural and human-made characteristics of the capital makes it prone to flooding. The results of the EAPI approach show that on one hand the concentration of pathogens in floodwater, and thus the risk of infection, decreases with the increase of the flood magnitude. On the other hand, larger floods can spread the pathogens further from the point source, threatening populations previously not identified as at risk by small-scale floods. The concept of EAPI is demonstrated for cholera but it can be extended to other waterborne diseases and also different pathways of exposure, requiring minimal adaptations. For future applications, better estimation of EAPI key components and improvement points are discussed and recommendations given for all the assessment steps.

Environmental impacts of mass drug administration programs: exposures, risks, and mitigation of antimicrobial resistance

Mass drug administration (MDA) of antimicrobials has shown promise in the reduction and potential elimination of a variety of neglected tropical diseases (NTDs). However, with antimicrobial resistance (AMR) becoming a global crisis, the risks posed by widespread antimicrobial use need to be evaluated. As the role of the environment in AMR emergence and dissemination has become increasingly recognized, it is likewise crucial to establish the role of MDA in environmental AMR pollution, along with the potential impacts of such pollution. This review presents the current state of knowledge on the antimicrobial compounds, resistant organisms, and antimicrobial resistance genes in MDA trials, routes of these determinants into the environment, and their persistence and ecological impacts, particularly in low and middle-income countries where these trials are most common. From the few studies directly evaluating AMR outcomes in azithromycin MDA trials, it is becoming apparent that MDA efforts can increase carriage and excretion of resistant pathogens in a lasting way. However, research on these outcomes for other antimicrobials used in MDA trials is sorely needed. Furthermore, while paths of AMR determinants from human waste to the environment and their persistence thereafter are supported by the literature, quantitative information on the scope and likelihood of this is largely absent. We recommend some mitigative approaches that would be valuable to consider in future MDA efforts. This review stands to be a valuable resource for researchers and policymakers seeking to evaluate the impacts of MDA.

Impact of Urbanization on Health and Well-Being in Ghana. Status of Research, Intervention Strategies and Future Directions: A Rapid Review

Introduction

Ghana like other African countries is facing multiple health threats due to expansion of urban populations. Globally, the urbanization phenomenon has received considerable attention and modest steps have been undertaken to address it. Ghana is stalling on implementation of policies and interventions targeted at alleviating the menace.

Objectives

This review examined research evidence, interventions, and policies relating to urbanization and threats to health and well-being of people living in Ghana. The review focused on three areas including urbanization threats to health and well-being, health risks associated with urbanization, and interventions and policies.

Materials and Methods

The search spanned from year 2000 to February 2022 covering documents related to urbanization, health, and well-being. Databases used for the search include African Journals Online, Annual Reviews (Biomedical, Life & Physical sciences, Social Sciences), BioMedCentral, BioOne, BLDS digital library, Cambridge University Press, ClinicalKey, CINAHL, University of Ghana Digital Collections/UGSpace, JSTOR, Medline and Wiley Online Library.

Results

Environmental risk factors, urban planning, water-related, behavior-related, and socioeconomic factors were important urbanization threats to health and well-being. Health risks identified include airborne diseases, waterborne diseases, malaria, and non-communicable diseases such as hypertension and lung cancer. Additionally, there is evidence of non-implementation and/or non-enforcement of existing interventions and policies.

Conclusion and Recommendation

Evidence from this rapid review shows that urbanization impacts on health and well-being of people in Ghana. Urbanization threats that expose populations to health risks could be reduced through commitment to implementation, surveillance and monitoring of policies and interventions. Communities and individuals must be equipped to take control of their health and well-being.

Development and validation of questionnaire to assess exposure of children to enteric infections in the rural northwest Ethiopia

In areas where children have multiple environmental exposures to enteric pathogens, identifying the sources of exposure by measuring external and internal exposures to enteric pathogens and complementing by questionnaire and observational checklist to capture behaviors resulting risk of exposure is critical. Accordingly, this study was conducted to design valid and reliable questionnaire to assess behaviors and environmental conditions resulting exposure to enteric pathogens in the rural northwest Ethiopia. We began with a thorough exploration of relevant literature to understand the theoretical framework on the research objectives to identify variables to highlight what the questionnaire is measuring. We then generated items in each domain that can effectively address the study objectives and we refined and organized the items in a suitable format. Then after, we conducted face and content validity by involving experts on the research subject. After pre-testing a pre-final version of the instrument generated in the content validity study, we conducted a pilot study in 150 randomly selected rural households to test the internal consistency reliability. We used content validity ratio (CVR), item-level content validity index (I-CVIs), scale-level content validity index (S-CVI/UA), and modified kappa statistics to measure content validity of items. Moreover, we used agreement and consistency indices (i.e., Cronbach's alpha) to assess the internal consistency of items. The content validity test result showed that the value of CVR was 0.95, I-CVIs was 0.97, and modified kappa was 0.97 for the whole items, indicating all the items are appropriate. The scale-level content validity index (S-CVI/UA) was 0.95 for the whole items indicating the agreement among judges to each items is higher. The internal consistency reliability test result indicated that Cronbach's alpha for the pre-final version of the pre-final tool was 0.85, indicating the strong reliability of the tool. The final version of the questionnaire was, therefore, prepared with 8 dimensions and 80 items. In this study, we designed valid and reliable questionnaire to assess behaviors and environmental conditions that result high risk of exposure to enteric infections in rural settings. The questionnaire can be used as a tool in the rural settings of developing countries with some amendments to account local contexts. However, this questionnaire alone does not measure exposure of children to enteric infections. It only complements external and internal exposure assessments.

Out of sight, out of mind: Understanding the sanitation crisis in global South cities

Global monitoring efforts do not provide a clear picture of the challenge of managing human waste at the city scale. Where cities do not provide universal access to publicly managed sanitation systems, households and communities find their own solutions resulting in a patchwork of approaches to removing human waste from places where people live. In dense urban environments, the absence of a coordinated approach can create serious public health problems. In the absence of comparable city-level data, we analyze primary and secondary data from 15 cities and 15 informal settlements in sub-Saharan Africa, South Asia, and Latin America. Across these regions, our study finds that 62 percent of human waste is not safely managed. We also find that, while many cities have a proportion of households connected to sewers, none of the 15 cities safely manage human waste at scale. In the absence of sewers, on-site fecal sludge management systems place enormous responsibility on households and private providers, and unaffordable sanitation options result in risky sanitation practices.

Fecal indicator bacteria along multiple environmental exposure pathways (water, food, and soil) and intestinal parasites among children in the rural northwest Ethiopia

Background

Children in low-resource settings are exposed to multiple risk factors for enteropathogens. However, the probability of exposures may be different across exposure pathways. Accordingly, this study was conducted to assess environmental exposures of children to intestinal parasites in the east Dembiya district of Ethiopia.

Methods

A cross-sectional study was conducted for 372 households with children aged 24–59 months. The potential for external exposure of children to intestinal parasites was assessed by determining the presence of fecal indicator organism (Escherichia coli (E. coli)) in drinking water at point of use, ready-to-eat foods, and courtyard soil from children’s outdoor play areas. For internal exposure assessment, ova of parasites in stool samples was detected using wet mount and Kato-Katz techniques to estimate exposure to intestinal parasites. The external and internal exposure assessments were also complemented using questionnaire and spot-check observations to assess behaviors that result in high risk of exposure. Individual and community-level predictors of intestinal parasites were identified using a multilevel logistic regression model. Statistically significant variables were identified on the basis of adjusted odds ratio (AOR) with 95% confidence interval (CI) and p-value < 0.05.

Results

Ova of one or more intestinal parasites was detected among 178 (47.8%) (95% CI 42.8, 52.6%) of the children. The most common intestinal parasites were A. lumbricoides (20.7%) and S. mansoni (19.1%). Furthermore, E. coli was detected in 69.1% of drinking water samples at point of use, 67.5% of ready-to-eat food samples, and 83.1% of courtyard soil samples from children’s outdoor play areas. Exposure of children to intestinal parasites among children in the studied region was associated with poor hand hygiene of mothers (AOR 1.98, 95% CI (1.07, 3.66), poor hand hygiene of children (AOR 3.20, 95% CI (1.77, 5.77), mouthing of soil contaminated materials (AOR 2.31, 95% CI (1.26, 4.24), open defecation practices (AOR 2.22, 95% CI (1.20, 4.10), limited access to water (AOR 2.38, 95% CI (1.13, 5.01), water contamination (AOR 2.51, 95% CI (1.31, 4.80), food contamination (AOR 3.21, 95% CI (1.69, 6.09), and soil contamination (AOR 2.56, 95% CI (1.34, 4.90).

Conclusion

An extensive E. coli contamination of water, foods, and courtyard soil was found in the studied region and the potential sources of contamination were open defecation practices, unhygienic disposal of wastes, poor animal husbandry and keeping practices, and poor water and food safety measures at household level. Moreover, fecal contamination of water, foods, and soil linked to exposure of children to intestinal parasites in the studied region. Thus, it is critical to implement individual-level interventions (such as latrine utilization, hand hygiene promotion, food safety, home-based water treatment, and containment of domestic animals), plus community-level interventions (such as protecting water sources from contamination, source-based water treatment, and community-driven sanitation).

Quantitative assessment of exposure to fecal contamination in urban environment across nine cities in low-income and lower-middle-income countries and a city in the United States

BACKGROUND

During 2014 to 2019, the SaniPath Exposure Assessment Tool, a standardized set of methods to evaluate risk of exposure to fecal contamination in the urban environment through multiple exposure pathways, was deployed in 45 neighborhoods in ten cities, including Accra and Kumasi, Ghana; Vellore, India; Maputo, Mozambique; Siem Reap, Cambodia; Atlanta, United States; Dhaka, Bangladesh; Lusaka, Zambia; Kampala, Uganda; Dakar, Senegal.

OBJECTIVE

Assess and compare risk of exposure to fecal contamination via multiple pathways in ten cities.

METHODS

In total, 4053 environmental samples, 4586 household surveys, 128 community surveys, and 124 school surveys were collected. E. coli concentrations were measured in environmental samples as an indicator of fecal contamination magnitude. Bayesian methods were used to estimate the distributions of fecal contamination concentration and contact frequency. Exposure to fecal contamination was estimated by the Monte Carlo method. The contamination levels of ten environmental compartments, frequency of contact with those compartments for adults and children, and estimated exposure to fecal contamination through any of the surveyed environmental pathways were compared across cities and neighborhoods.

RESULTS

Distribution of fecal contamination in the environment and human contact behavior varied by city. Universally, food pathways were the most common dominant route of exposure to fecal contamination across cities in low-income and lower-middle-income countries. Risks of fecal exposure via water pathways, such as open drains, flood water, and municipal drinking water, were site-specific and often limited to smaller geographic areas (i.e., neighborhoods) instead of larger areas (i.e., cities).

CONCLUSIONS

Knowledge of the relative contribution to fecal exposure from multiple pathways, and the environmental contamination level and frequency of contact for those "dominant pathways" could provide guidance for Water, Sanitation, and Hygiene (WASH) programming and investments and enable local governments and municipalities to improve intervention strategies to reduce the risk of exposure to fecal contamination.

Quantitative assessment of exposure to fecal contamination in urban environment across nine cities in low-income and lower-middle-income countries and a city in the United States

BACKGROUND

During 2014 to 2019, the SaniPath Exposure Assessment Tool, a standardized set of methods to evaluate risk of exposure to fecal contamination in the urban environment through multiple exposure pathways, was deployed in 45 neighborhoods in ten cities, including Accra and Kumasi, Ghana; Vellore, India; Maputo, Mozambique; Siem Reap, Cambodia; Atlanta, United States; Dhaka, Bangladesh; Lusaka, Zambia; Kampala, Uganda; Dakar, Senegal.

OBJECTIVE

Assess and compare risk of exposure to fecal contamination via multiple pathways in ten cities.

METHODS

In total, 4053 environmental samples, 4586 household surveys, 128 community surveys, and 124 school surveys were collected. E. coli concentrations were measured in environmental samples as an indicator of fecal contamination magnitude. Bayesian methods were used to estimate the distributions of fecal contamination concentration and contact frequency. Exposure to fecal contamination was estimated by the Monte Carlo method. The contamination levels of ten environmental compartments, frequency of contact with those compartments for adults and children, and estimated exposure to fecal contamination through any of the surveyed environmental pathways were compared across cities and neighborhoods.

RESULTS

Distribution of fecal contamination in the environment and human contact behavior varied by city. Universally, food pathways were the most common dominant route of exposure to fecal contamination across cities in low-income and lower-middle-income countries. Risks of fecal exposure via water pathways, such as open drains, flood water, and municipal drinking water, were site-specific and often limited to smaller geographic areas (i.e., neighborhoods) instead of larger areas (i.e., cities).

CONCLUSIONS

Knowledge of the relative contribution to fecal exposure from multiple pathways, and the environmental contamination level and frequency of contact for those "dominant pathways" could provide guidance for Water, Sanitation, and Hygiene (WASH) programming and investments and enable local governments and municipalities to improve intervention strategies to reduce the risk of exposure to fecal contamination.

Detection and Quantification of Enteric Pathogens in Aerosols Near Open Wastewater Canals in Cities with Poor Sanitation

Urban sanitation infrastructure is inadequate in many low-income countries, leading to the presence of highly concentrated, uncontained fecal waste streams in densely populated areas. Combined with mechanisms of aerosolization, airborne transport of enteric microbes and their genetic material is possible in such settings but remains poorly characterized. We detected and quantified enteric pathogen-associated gene targets in aerosol samples near open wastewater canals (OWCs) or impacted (receiving sewage or wastewater) surface waters and control sites in La Paz, Bolivia; Kanpur, India; and Atlanta, USA, via multiplex reverse-transcription qPCR (37 targets) and ddPCR (13 targets). We detected a wide range of enteric targets, some not previously reported in extramural urban aerosols, with more frequent detections of all enteric targets at higher densities in La Paz and Kanpur near OWCs. We report density estimates ranging up to 4.7 × 10² gc per m_air³ across all targets including heat-stable enterotoxigenic Escherichia coli, Campylobacter jejuni, enteroinvasive E. coli/Shigella spp., Salmonella spp., norovirus, and Cryptosporidium spp. Estimated 25, 76, and 0% of samples containing positive pathogen detects were accompanied by culturable E. coli in La Paz, Kanpur, and Atlanta, respectively, suggesting potential for viability of enteric microbes at the point of sampling. Airborne transmission of enteric pathogens merits further investigation in cities with poor sanitation.

A planetary health model for reducing exposure to faecal contamination in urban informal settlements: Baseline findings from Makassar, Indonesia

BACKGROUND

The intense interactions between people, animals and environmental systems in urban informal settlements compromise human and environmental health. Inadequate water and sanitation services, compounded by exposure to flooding and climate change risks, expose inhabitants to environmental contamination causing poor health and wellbeing and degrading ecosystems. However, the exact nature and full scope of risks and exposure pathways between human health and the environment in informal settlements are uncertain. Existing models are limited to microbiological linkages related to faecal-oral exposures at the individual level, and do not account for a broader range of human-environmental variables and interactions that affect population health and wellbeing.

METHODS

We undertook a 12-month health and environmental assessment in 12 flood-prone informal settlements in Makassar, Indonesia. We obtained caregiver-reported health data, anthropometric measurements, stool and blood samples from children < 5 years, and health and wellbeing data for children 5-14 years and adult respondents. We collected environmental data including temperature, mosquito and rat species abundance, and water and sediment samples. Demographic, built environment and household asset data were also collected. We combined our data with existing literature to generate a novel planetary health model of health and environment in informal settlements.

RESULTS

Across the 12 settlements, 593 households and 2764 participants were enrolled. Two-thirds (64·1%) of all houses (26·3-82·7% per settlement) had formal land tenure documentation. Cough, fever and diarrhoea in the week prior to the survey were reported among an average of 34.3%, 26.9% and 9.7% of children aged < 5 years, respectively; although proportions varied over time, prevalence among these youngest children was consistently higher than among children 5-14 years or adult respondents. Among children < 5 years, 44·3% experienced stunting, 41·1% underweight, 12.4% wasting, and 26.5% were anaemic. There was self- or carer-reported poor mental health among 16.6% of children aged 5-14 years and 13.9% of adult respondents. Rates of potential risky exposures from swimming in waterways, eating uncooked produce, and eating soil or dirt were high, as were exposures to flooding and livestock. Just over one third of households (35.3%) had access to municipal water, and contamination of well water with E. coli and nitrogen species was common. Most (79·5%) houses had an in-house toilet, but no houses were connected to a piped sewer network or safe, properly constructed septic tank. Median monthly settlement outdoor temperatures ranged from 26·2 °C to 29.3 °C, and were on average, 1·1 °C warmer inside houses than outside. Mosquito density varied over time, with Culex quinquefasciatus accounting for 94·7% of species. Framed by a planetary health lens, our model includes four thematic domains: (1) the physical/built environment; (2) the ecological environment; (3) human health; and (4) socio-economic wellbeing, and is structured at individual, household, settlement, and city/beyond spatial scales.

CONCLUSIONS

Our planetary health model includes key risk factors and faecal-oral exposure pathways but extends beyond conventional microbiological faecal-oral enteropathogen exposure pathways to comprehensively account for a wider range of variables affecting health in urban informal settlements. It includes broader ecological interconnections and planetary health-related variables at the household, settlement and city levels. It proposes a composite framework of markers to assess water and sanitation challenges and flood risks in urban informal settlements for optimal design and monitoring of interventions.

Impacts of an Urban Sanitation Intervention on Fecal Indicators and the Prevalence of Human Fecal Contamination in Mozambique

Fecal source tracking (FST) may be useful to assess pathways of fecal contamination in domestic environments and to estimate the impacts of water, sanitation, and hygiene (WASH) interventions in low-income settings. We measured two nonspecific and two human-associated fecal indicators in water, soil, and surfaces before and after a shared latrine intervention from low-income households in Maputo, Mozambique, participating in the Maputo Sanitation (MapSan) trial. Up to a quarter of households were impacted by human fecal contamination, but trends were unaffected by improvements to shared sanitation facilities. The intervention reduced Escherichia coli gene concentrations in soil but did not impact culturable E. coli or the prevalence of human FST markers in a difference-in-differences analysis. Using a novel Bayesian hierarchical modeling approach to account for human marker diagnostic sensitivity and specificity, we revealed a high amount of uncertainty associated with human FST measurements and intervention effect estimates. The field of microbial source tracking would benefit from adding measures of diagnostic accuracy to better interpret findings, particularly when FST analyses convey insufficient information for robust inference. With improved measures, FST could help identify dominant pathways of human and animal fecal contamination in communities and guide the implementation of effective interventions to safeguard health.

The Applications of Implementation Science in Water, Sanitation, and Hygiene (WASH) Research and Practice

BACKGROUND

Delivery of high quality, at-scale, and sustained services is a major challenge in the water, sanitation, and hygiene (WASH) sector, made more challenging by a dearth of evidence-based models for adaption across contexts in low- and middle-income countries.

OBJECTIVE

We aim to describe the value of implementation science (IS) for the WASH sector and provide recommendations for its application.

METHODS

We review concepts from the growing field of IS-defined as the "scientific study of methods to promote the systematic uptake of research findings and other evidence-based practices into routine practice, and hence, to improve the quality and effectiveness of health services"-and we translate their relevance to WASH research, learning, and delivery.

DISCUSSION

IS provides a suite of methods and theories to systematically develop, evaluate, and scale evidence-based interventions. Though IS thinking has been applied most notably in health services delivery in high-income countries, there have been applications in low-income settings in fields such as HIV/AIDS and nutrition. Expanding the application of IS to environmental health, specifically WASH interventions, would respond to the complexity of sustainable service delivery. WASH researchers may want to consider applying IS guidelines to their work, including adapting pragmatic research models, using established IS frameworks, and cocreating knowledge with local stakeholders. https://doi.org/10.1289/EHP7762.

Household Water, Sanitation, and Hygiene Practices Impact Pathogen Exposure in Remote, Rural, Unpiped Communities

Household water, sanitation and hygiene (WASH) practices in remote, rural, and unpiped communities are likely to impact exposure to pathogens beyond the fecal-oral transmission routes that are typically prioritized in WASH interventions. We studied 43 homes in two remote, rural, unpiped communities in Alaska to evaluate seasonal water haul, water sources, water quality, and water reuse, as well as greywater and human waste disposal over 1 year. Hauled quantities of water reportedly ranged from 3.0 to 5.4 gallons per capita per day (gpcd) depending on the community and season. Natural, untreated water sources contributed 0.5-1.1 gpcd to household water availability. Reported quantities of water hauled were significantly correlated with total water storage capacity in the home. Total coliforms were detected in 30-60% of stored household water samples from treated and untreated sources, and total coliform counts were significantly higher in specific sources and during specific seasons. Exposure to pathogens during periods of low water access, from untreated water reuse, from greywater disposal and from human waste disposal are important pathways of disease transmission in these remote, rural, unpiped communities. We discuss intermediate steps that can be taken at the household and community levels to interrupt exposure pathways before piped infrastructure is installed. This model of examining specific household practices to determine transmission routes can be applied to other remote communities or unique conditions to aid in the recommendation of targeted WASH interventions.

Navigating Data Uncertainty and Modeling Assumptions in Quantitative Microbial Risk Assessment in an Informal Settlement in Kampala, Uganda

Decision-makers in developing communities often lack credible data to inform decisions related to water, sanitation, and hygiene. Quantitative microbial risk assessment (QMRA), which quantifies pathogen-related health risks across exposure routes, can be informative; however, the utility of QMRA for decision-making is often undermined by data gaps. This work integrates QMRA, uncertainty and sensitivity analyses, and household surveys in Bwaise, Kampala (Uganda) to characterize the implications of censored data management, identify sources of uncertainty, and incorporate risk perceptions to improve the suitability of QMRA for informal settlements or similar settings. In Bwaise, drinking water, hand rinse, and soil samples were collected from 45 households and supplemented with data from 844 surveys. Quantified pathogen (adenovirus, Campylobacter jejuni, and Shigella spp./EIEC) concentrations were used with QMRA to model infection risks from exposure through drinking water, hand-to-mouth contact, and soil ingestion. Health risks were most sensitive to pathogen data, hand-to-mouth contact frequency, and dose-response models (particularly C. jejuni). When managing censored data, results from upper limits of detection, half of limits of detection, and uniform distributions returned similar results, which deviated from lower limits of detection and maximum likelihood estimation imputation approaches. Finally, risk perceptions (e.g., it is unsafe to drink directly from a water source) were identified to inform risk management.

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

We conducted a controlled before-and-after trial to evaluate the impact of an onsite urban sanitation intervention on the prevalence of enteric infection, soil transmitted helminth re-infection, and diarrhea among children in Maputo, Mozambique. A non-governmental organization replaced existing poor-quality latrines with pour-flush toilets with septic tanks serving household clusters. We enrolled children aged 1-48 months at baseline and measured outcomes before and 12 and 24 months after the intervention, with concurrent measurement among children in a comparable control arm. Despite nearly exclusive use, we found no evidence that intervention affected the prevalence of any measured outcome after 12 or 24 months of exposure. Among children born into study sites after intervention, we observed a reduced prevalence of Trichuris and Shigella infection relative to the same age group at baseline (<2 years old). Protection from birth may be important to reduce exposure to and infection with enteric pathogens in this setting.

Ex-ante quantification of nutrient, total solids, and water flows in sanitation systems

To prioritise sustainable sanitation systems in strategic sanitation planning, indicators such as local appropriateness or resource recovery have to be known at the pre-planning phase. The quantification of resource recovery remains a challenge because existing substance flow models require large amounts of input data and can therefore only be applied for a few options at a time for which implementation examples exist. This paper aims to answer two questions: How can we predict resource recovery and losses of sanitation systems ex-ante at the pre-planning phase? And how can we do this efficiently to consider the entire sanitation system option space? The approach builds on an existing model to create all valid sanitation systems from a set of conventional and emerging technologies and to evaluate their appropriateness for a given application case. It complements the previous model with a Substance Flow Model (SFM) and with transfer coefficients from a technology library to quantify nutrients (phosphorus and nitrogen), total solids (as an indicator for energy and organics), and water flows in sanitation systems ex ante. The transfer coefficients are based on literature data and expert judgement. Uncertainties resulting from the variability of literature data or ignorance of experts are explicitly considered, allowing to assess the robustness of the model output. Any (future) technologies or additional products can easily be added to the library. The model is illustrated with a small didactic example showing how 12 valid system configurations are generated from a few technologies, and how substance flows, recovery ratios, and losses to soil, air, and water are quantified considering uncertainties. The recovery ratios vary between 0 and 28% for phosphorus, 0-10% for nitrogen, 0-26% for total solids, and 0-12% for water. The uncertainties reflect the high variability of the literature data but are comparable to those obtained in studies using a conventional post-ante material flow analysis (generally about 30% variability at the scale of a an urban area). Because the model is fully automated and based on literature data, it can be applied ex-ante to a large and diverse set of possible sanitation systems as shown with a real application case. From the 41 technologies available in the library, 101,548 systems are generated and substance flows are modelled. The resulting recovery ratios range from nothing to almost 100%. The two examples also show that recovery depend on technology interactions and has therefore to be assessed for all possible system configurations and not at the single technology level only. The examples also show that there exist trade-offs among different types of reuse (e.g. energy versus nutrients) or different sustainability indicators (e.g. local appropriateness versus resource recovery). These results show that there is a need for such an automated and generic approach that provides recovery data for all system configurations already at the pre-planning phase. The approach presented enables to integrate transparently the best available knowledge for a growing number of sanitation technologies into a planning process. The resulting resource recovery and loss ratios can be used to prioritise resource efficient systems in sanitation planning, either for the pre-selection or the detailed evaluation of options using e.g. MCDA. The results can also be used to guide future development of technology and system innovations. As resource recovery becomes more relevant and novel sanitation technologies and system options emerge, the approach presents itself as a useful tool for strategic sanitation planning in line with the Sustainable Development Goals (SDGs).

Modelling faecal pathogen flows and health risks in urban Bangladesh: Implications for sanitation decision making

Faecal-oral infections are a major component of the disease burden in low-income contexts, with inadequate sanitation seen as a contributing factor. However, demonstrating health effects of sanitation interventions - particularly in urban areas - has proved challenging and there is limited empirical evidence to support sanitation decisions that maximise health gains. This study aimed to develop, apply and validate a systems modelling approach to inform sanitation infrastructure and service decision-making in urban environments by examining enteric pathogen inputs, transport and reduction by various sanitation systems, and estimating corresponding exposure and public health impacts. The health effects of eight sanitation options were assessed in a low-income area in Dhaka, Bangladesh, with a focus on five target pathogens (Shigella, Vibrio cholerae, Salmonella Typhi, norovirus GII and Giardia). Relative to the sanitation base case in the study site (24% septic tanks, 5% holding tanks and 71% toilets discharging directly to open drains), comprehensive coverage of septic tanks was estimated to reduce the disease burden in disability-adjusted life years (DALYs) by 48-72%, while complete coverage of communal scale anaerobic baffled reactors was estimated to reduce DALYs by 67-81%. Despite these improvements, a concerning health risk persists with these systems as a result of effluent discharge to open drains, particularly when the systems are poorly managed. Other sanitation options, including use of constructed wetlands and small bore sewerage, demonstrated further reductions in local health risk, though several still exported pathogens into neighbouring areas, simply transferring risk to downstream communities. The study revealed sensitivity to and a requirement for further evidence on log reduction values for different sanitation systems under varying performance conditions, pathogen flows under flooding conditions as well as pathogen shedding and human exposure in typical low-income urban settings. Notwithstanding variability and uncertainties in input parameters, systems modelling can be a feasible and customisable approach to consider the relative health impact of different sanitation options across various contexts, and stands as a valuable tool to guide urban sanitation decision-making.

The utility of Escherichia coli as a contamination indicator for rural drinking water: Evidence from whole genome sequencing

Across the water sector, Escherichia coli is the preferred microbial water quality indicator and current guidance upholds that it indicates recent faecal contamination. This has been challenged, however, by research demonstrating growth of E. coli in the environment. In this study, we used whole genome sequencing to investigate the links between E. coli and recent faecal contamination in drinking water. We sequenced 103 E. coli isolates sampled from 9 water supplies in rural Kitui County, Kenya, including points of collection (n = 14) and use (n = 30). Biomarkers for definitive source tracking remain elusive, so we analysed the phylogenetic grouping, multi-locus sequence types (MLSTs), allelic diversity, and virulence and antimicrobial resistance (AMR) genes of the isolates for insight into their likely source. Phylogroup B1, which is generally better adapted to water environments, is dominant in our samples (n = 69) and allelic diversity differences (z = 2.12, p = 0.03) suggest that naturalised populations may be particularly relevant at collection points with lower E. coli concentrations (<50 / 100mL). The strains that are more likely to have originated from human and/or recent faecal contamination (n = 50), were found at poorly protected collection points (4 sites) or at points of use (12 sites). We discuss the difficulty of interpreting health risk from E. coli grab samples, especially at household level, and our findings support the use of E. coli risk categories and encourage monitoring that accounts for sanitary conditions and temporal variability.

Measuring Environmental Exposure to Enteric Pathogens in Low-Income Settings: Review and Recommendations of an Interdisciplinary Working Group

Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments.

Developing sanitation planning options: A tool for systematic consideration of novel technologies and systems

To provide access to sustainable sanitation for the entire world population, novel technologies and systems have been developed. These options are often independent of sewers, water, and energy and therefore promise to be more appropriate for fast-growing urban areas. They also allow for resource recovery and and are adaptable to changing environmental and demographic conditions what makes them more sustainable. More options, however, also enhance planning complexity. Structured decision making (SDM) can help balance opposing interests. Yet, most of the current research focuses on the selection of a preferred option, assuming that a set of appropriate options is available. There is a lack of reproducible methods for the identification of sanitation system planning options that can consider the growing number of available technology and the many possible system configurations. Additionally, there is a lack of data, particularly for novel options, to evaluate the various sustainability criteria for sanitation.To overcome this limitation, we present a novel software supported approach: the SANitation sysTem Alternative GeneratOr (Santiago). To be optimally effective, Santiago is required to be integrated into an SDM approach. In this paper, we present all the elements that such an integration requires and illustrate these methods at the case of Arba Minch, a fast growing town in Ethiopia. Based on this example and experiences from other cases, we discuss the lessons learnt and present the advantages potentially brought by Santiago for sanitation planning The integration requires four elements: a set of technologies to be looked at, decision objectives for sustainable sanitation, screening criteria to evalute technology appropriateness, and about the technologies and the casea. The main output is a set of sanitation system options that is locally appropriate, diverse in order to reveal trade-offs, and of a manageable size. To support the definition of decision objectives, we developed a generic objective hierarchy for sustainable sanitation. Because one of the main challenges lies in the quantification of screening criteria, we established the data for 27 criteria and 41 technologies in a library.The case studies showed, that if the integration is successful, then Santiago can provide substantial benefits: (i) it is systematic and reproducible; (ii) it opens up the decision space with novel and potentially more appropriate solutions; (iii) it makes international data accessible for more empirical decision making; (iv) it enables decisions based on strategic objectives in line with the sustainable development goals; (v) it allows to prioritise appropriate and resource efficient systems right from the beginning (vi) and it contributes to a more citywide inclusive approach by birding strategic objectives with an area-based appropriateness assessment. The here presented approach enables the prioritisation of appropriate and resource efficient sanitation technologies and systems in strategic planning. Thereby this approach contributes to SDG 6.2, 6.3, and 11, sustainable sanitation for all.

Are There Seasonal Variations in Faecal Contamination of Exposure Pathways? An Assessment in a Low-Income Settlement in Uganda

Sanitation infrastructure are not able to cope with the increasing population in low-income countries, which leaves populations exposed to faecal contamination from multiple pathways. This study evaluated public health risk (using SaniPath) in a low-income community during the dry season, to identify the dominant exposure pathways, and compare this data to existing data for the rainy season, questioning the assumption that risk of faecal contamination is higher in the rainy season. SaniPath was used to collect and assess exposure and environmental data, and to generate risk profiles for each pathway. In the dry season the highest exposure frequency was for bathing and street food, exposure frequency generally increased, and seasonal variation was found in five pathways. The highest hazards in the dry season were through contact with drains, soil, and street food. Seasonal variation was found in the contamination of open drains and street food, with higher levels of Escherichia coli (E. coli) in the dry season. Open drains were identified as the most dominant risk pathway in both seasons, but risk was higher in the dry season. This highlights the complex nature of seasonal variation of faecal risk, and questions the assumption that risk is higher in the rainy season.

Faecal contamination of the environment and child health: a systematic review and individual participant data meta-analysis

BACKGROUND

Exposure to faecal contamination is believed to be associated with child diarrhoea and possibly stunting; however, few studies have explicitly measured the association between faecal contamination and health. We aimed to assess individual participant data (IPD) across multiple trials and observational studies to quantify the relationship for common faecal-oral transmission pathways.

METHODS

We did a systematic review and meta-analysis of IPD from studies identified in an electronic search of PubMed, Web of Science, and Embase on May 21, 2018. The search was done in English, but full texts published in French, Portuguese, and Spanish were also reviewed. Eligible studies quantified (1) household-level faecal indicator bacteria concentrations along common faecal-oral transmission pathways of drinking water, soil, or food, on children's hands or fomites, or fly densities in food preparation areas; and (2) individual-level diarrhoea or linear growth measures for children younger than 5 years in low-income and middle-income countries. For the diarrhoea analysis, all definitions of diarrhoea were eligible but studies were excluded if they used a recall period longer than 7 days. For the linear growth analysis (using height-for-age Z scores [HAZ]), cross-sectional studies were excluded, because of the absence of longitudinal environmental contamination data measured before the growth outcomes. We used multilevel generalised mixed-effects models to estimate the odds ratio (OR) for diarrhoea and the difference in HAZ scores for individual studies associated with a 1-log₁₀ higher measure of faecal contamination. Estimates from each study were combined under a random-effects meta-analysis framework. The study protocol was pre-registered with PROSPERO (CRD42018102114).

FINDINGS

From 72 eligible studies, we included IPD for 20 studies in the meta-analyses, totalling 54 225 diarrhoea or linear growth observations matched to faecal indicator bacteria concentrations in drinking water, and a further 35 010 observations with faecal contamination data for the other transmission pathways. Child diarrhoea was associated with 1-log₁₀ higher faecal indicator bacteria concentrations in drinking water (OR 1·09, 95% CI 1·04 to 1·13; p=0·0002, I²=34%, 95% CI 0 to 62) and on children's hands (1·11, 1·02 to 1·22; p=0·021, I²=0%, 0 to 71). Lower HAZ scores were associated with 1-log₁₀ higher median faecal indicator bacteria concentrations in drinking water (HAZ -0·04, 95% CI -0·06 to -0·01; p=0·0054; I²=19%, 95% CI 0 to 63) and on fomites (-0·06, -0·12 to 0·00; p=0·044, I²=57%, 0 to 90).

INTERPRETATION

Although summary measures from individual studies often report little or no effect of measured faecal contamination on child health, this multi-study IPD analysis indicates that household faecal indicator bacteria concentrations are associated with important adverse health outcomes in young children. Improved direct measures of exposure and enteric pathogens could help to better characterise the relationship and inform intervention design in future studies.

FUNDING

None.

The SaniPath Exposure Assessment Tool: A quantitative approach for assessing exposure to fecal contamination through multiple pathways in low resource urban settlements

Inadequate sanitation can lead to exposure to fecal contamination through multiple environmental pathways and can result in adverse health outcomes. By understanding the relative importance of multiple exposure pathways, sanitation interventions can be tailored to those pathways with greatest potential public health impact. The SaniPath Exposure Assessment Tool allows users to identify and quantify human exposure to fecal contamination in low-resource urban settings through a systematic yet customizable process. The Tool includes: a project management platform; mobile data collection and a data repository; protocols for primary data collection; and automated exposure assessment analysis. The data collection protocols detail the process of conducting behavioral surveys with households, school children, and community groups to quantify contact with fecal exposure pathways and of collecting and analyzing environmental samples for E. coli as an indicator of fecal contamination. Bayesian analyses are used to estimate the percentage of the population exposed and the mean dose of fecal exposure from microbiological and behavioral data. Fecal exposure from nine pathways (drinking water, bathing water, surface water, ocean water, open drains, floodwater, raw produce, street food, and public or shared toilets) can be compared through a common metric-estimated ingestion of E. coli units (MPN or CFU) per month. The Tool generates data visualizations and recommendations for interventions designed for both scientific and lay audiences. When piloted in Accra, Ghana, the results of the Tool were comparable with that of an in-depth study conducted in the same neighborhoods and highlighted consumption of raw produce as a dominant exposure pathway. The Tool has been deployed in nine cities to date, and the results are being used by local authorities to design and prioritize programming and policy. The SaniPath Tool is a novel approach to support public-health evidence-based decision-making for urban sanitation policies and investments.

Does suboptimal household flooring increase the risk of diarrhoea and intestinal parasite infection in low and middle income endemic settings? A systematic review and meta-analysis protocol

BACKGROUND

Water, sanitation, and hygiene interventions often fail to show long-term impact on diarrhoeal and/or intestinal parasite risk in many low- and middle-income countries. Less attention has been paid to wider contextual factors that may contribute to high levels of contamination in the domestic environment such as household flooring. The purpose of this study will be to assess the association between diarrhoeal and/or intestinal parasite infection status and unimproved/unfinished flooring in low- and middle-income countries.

METHODS

We will conduct a comprehensive search of published studies (randomized controlled trials, non-randomized controlled trials, and observational studies) that examined the association between unimproved/unfinished household flooring and diarrhoeal and/or intestinal parasite infection status from January 1, 1980, onwards with no language restriction. The primary outcome will include diarrhoeal and/or intestinal parasite infection status. Databases to be searched include EMBASE, MEDLINE, Web of Science, and Google Scholar. The secondary outcome will be the association between specific pathogens (laboratory confirmed) and unimproved/unfinished household flooring. Independent screening for eligible studies using defined criteria and data extraction will be completed in duplicate and independently. Any discrepancies between the two reviewers will be resolved by consensus and/or arbitration by a third researcher. If data permits, random effects models will be used where appropriate. Subgroup and additional analyses will be conducted to explore the potential sources of heterogeneity (e.g. age group, geographical region) and potential risk of bias of included studies.

DISCUSSION

This review will provide a comprehensive examination of a possible association between suboptimal household flooring and increased risk of enteric pathogen infection, highlight gaps for future research in high risk areas, and inform intervention design for future planned studies in Kenya and/or elsewhere in the region.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42019156437.

Effect of Sanitation Improvements on Pathogens and Microbial Source Tracking Markers in the Rural Bangladeshi Household Environment

Diarrheal illnesses from enteric pathogens are a leading cause of death in children under five in low- and middle-income countries (LMICs). Sanitation is one way to reduce the spread of enteric pathogens in the environment; however, few studies have investigated the effectiveness of sanitation in rural LMICs in reducing pathogens in the environment. In this study, we measured the impact of a sanitation intervention (dual-pit latrines, sani-scoops, child potties delivered as part of a randomized control trial, WASH Benefits) in rural Bangladeshi household compounds by assessing prevalence ratios, differences, and changes in the concentration of pathogen genes and host-specific fecal markers. We found no difference in the prevalence of pathogenic Escherichia coli, norovirus, or Giardia genes in the domestic environment in the sanitation and control arms. The prevalence of the human fecal marker was lower on child hands and the concentration of animal fecal marker was lower on mother hands in the sanitation arm in adjusted models, but these associations were not significant after correcting for multiple comparisons. In the subset of households with ≥10 individuals per compound, the prevalence of enterotoxigenic E. coli genes on child hands was lower in the sanitation arm. Incomplete removal of child and animal feces or the compound (versus community-wide) scale of intervention could explain the limited impacts of improved sanitation.

Variation in E. coli concentrations in open drains across neighborhoods in Accra, Ghana: The influence of onsite sanitation coverage and interconnectedness of urban environments

Alongside efforts to improve safe management of feces along the entire sanitation chain, including after the toilet, global sanitation efforts are focusing on universal access 'basic' services: onsite facilities that safely contain excreta away from human contact. Although fecal sludge management is improving in urban areas, open drains remain a common fate for feces in these often densely-populated neighborhoods in low-income countries. To-date, it is unclear to what extent complete coverage of onsite sanitation reduces fecal contamination in the urban environment and how fecal contamination varies within urban drains across neighborhoods by sanitation status within a city. We assessed how neighborhood levels of environmental fecal contamination (via spatially-representative sampling of open drains for E. coli) varied across four neighborhoods with varying income, type and coverage of household sanitation facilities, and population density in Accra, Ghana. Neighborhoods with very high sanitation coverage (≥89%) still had high (>4 log10 CFU/100 mL) E. coli concentrations in drains. Between-neighborhood variation in E. coli levels among the high coverage neighborhoods was significant: drain concentrations in neighborhoods with 93% and 89% coverage (4.7 (95% CI: 4.5, 4.9) & 4.9 (95% CI: 4.5, 5.3) log10 CFU/100 mL, respectively) were higher than in the neighborhood with 97% coverage (4.1 log10 CFU/100 mL, 95% CI: 3.8, 4.4 log10 CFU/100 mL). Compared with the highest coverage neighborhood, the neighborhood with lowest coverage (48%) also had higher E. coli concentrations (5.6 log10 CFU/100 mL, 95% CI: 5.3, 5.9 log10 CFU/100 mL). Although fecal contamination in open drains appeared lower in neighborhoods with higher onsite sanitation coverage (and vice versa), other factors (e.g. fecal sludge management, animals, population density) may affect drain concentrations. These results underscore that neighborhood-level onsite sanitation improvements alone may not sufficiently reduce fecal hazards to public health from open drains. These findings supporting the need for integrated, city-level fecal sludge management alongside multifaceted interventions to reduce fecal contamination levels and human exposure.

Characterization of the gut microbiota of Nicaraguan children in a water insecure context

OBJECTIVES

The gut microbiota varies across human populations. The first years of life are a critical period in its development. While delivery mode and diet contribute to observed variation, the additional contribution of specific environmental factors remains poorly understood. One factor is waterborne enteric pathogen exposure. In this pilot study, we explore the relationship between household water security and the gut microbiota of children.

METHODS

From Nicaraguan households (n = 39), we collected drinking water samples, as well as fecal samples from children aged one month to 5.99 years (n = 53). We tested water samples for total coliforms (CFU/mL) and the presence of common enteric pathogens. Composition and diversity of the gut microbiota were characterized by 16S rRNA sequencing. Households were classified as having drinking water that was "low" (<29 CFU/mL) or "high" (≥29 CFU/mL) in coliforms. We used permutational analyses of variance and Mann-Whitney U-tests to identify differences in the composition and diversity of the gut microbiota of children living in these two home types.

RESULTS

Insecure access led households to store drinking water and 85% tested positive for coliforms. High concentrations of Salmonella and Campylobacter were found in water and fecal samples. Controlling for age, the gut microbiota of children from high coliform homes were compositionally different and less diverse than those from low coliform homes.

CONCLUSIONS

Results indicate that research exploring the ways water insecurity affects human biology should consider the gut microbiome and that investigations of inter-population variation in the gut microbial community of children should consider pathogen exposure and infection.

Quantitative assessment of fecal contamination in multiple environmental sample types in urban communities in Dhaka, Bangladesh using SaniPath microbial approach

Rapid urbanization has led to a growing sanitation crisis in urban areas of Bangladesh and potential exposure to fecal contamination in the urban environment due to inadequate sanitation and poor fecal sludge management. Limited data are available on environmental fecal contamination associated with different exposure pathways in urban Dhaka. We conducted a cross-sectional study to explore the magnitude of fecal contamination in the environment in low-income, high-income, and transient/floating neighborhoods in urban Dhaka. Ten samples were collected from each of 10 environmental compartments in 10 different neighborhoods (4 low-income, 4 high-income and 2 transient/floating neighborhoods). These 1,000 samples were analyzed with the IDEXX-Quanti-Tray technique to determine most-probable-number (MPN) of E. coli. Samples of open drains (6.91 log10 MPN/100 mL), surface water (5.28 log10 MPN/100 mL), floodwater (4.60 log10 MPN/100 mL), produce (3.19 log10 MPN/serving), soil (2.29 log10 MPN/gram), and street food (1.79 log10 MPN/gram) had the highest mean log10 E. coli contamination compared to other samples. The contamination concentrations did not differ between low-income and high-income neighborhoods for shared latrine swabs, open drains, municipal water, produce, and street foodsamples. E. coli contamination levels were significantly higher (p <0.05) in low-income neighborhoods compared to high-income for soil (0.91 log10 MPN/gram, 95% CI, 0.39, 1.43), bathing water (0.98 log10 MPN/100 mL, 95% CI, 0.41, 1.54), non-municipal water (0.64 log10 MPN/100 mL, 95% CI, 0.24, 1.04), surface water (1.92 log10 MPN/100 mL, 95% CI, 1.44, 2.40), and floodwater (0.48 log10 MPN/100 mL, 95% CI, 0.03, 0.92) samples. E. coli contamination were significantly higher (p<0.05) in low-income neighborhoods compared to transient/floating neighborhoods for drain water, bathing water, non-municipal water and surface water. Future studies should examine behavior that brings people into contact with the environment and assess the extent of exposure to fecal contamination in the environment through multiple pathways and associated risks.

Translating pathogen knowledge to practice for sanitation decision-making

Sanitation planners make complex decisions in the delivery of sanitation services to achieve health outcomes. We present findings from a stakeholder engagement workshop held in Kampala, Uganda, to educate, interact with, and solicit feedback from participants on how the relevant scientific literature on pathogens can be made more accessible to practitioners to support decision-making. We targeted Water, Sanitation and Hygiene (WASH) practitioners involved in different levels of service delivery. Practitioners revealed that different sanitation planning tools are used to inform decision-making; however, most of these tools are not user-friendly or adapted to meet their needs. Most stakeholders (68%) expressed familiarity with pathogens, yet less than half (46%) understood that fecal coliforms were bacteria and used as indicators for fecal pollution. A number of stakeholders were unaware that fecal indicator bacteria do not behave and persist the same as helminths, protozoa, or viruses, making fecal indicator bacteria inadequate for assessing pathogen reductions for all pathogen groups. This suggests a need for awareness and capacity development around pathogens found in excreta. The findings underscore the importance to engage stakeholders in the development of support tools for sanitation planning and highlighted broader opportunities to bridge science with practice in the WASH sector.

Integrated value-chain and risk assessment of Pig-Related Zoonoses in Ghana

The marked increase in the pig-trade in Ghana has raised concerns about increased transmission of related zoonotic diseases. A study on pig-related zoonoses along the pork value-chain was conducted in Greater Accra and Upper East Regions of Ghana. Results showed significant taenia (60%) and trichinella (8%) seroprevalence in pigs in Upper East with little evidence of transmission to humans. Sero-prevalence of HEV was high in both pigs (85%) and humans (37%). Sero-prevalence rates were significantly higher in Upper East than Greater Accra. Pig handlers in Accra had significantly higher sero-prevalence rates (58%) than other community members (18%) but there was no such association in the Upper East. Given the high rates of mortality, miscarriage and stillbirth associated with HEV in pregnancy, it is a cause for concern that 31% women of child-bearing age tested sero-positive for HEV.

A localized sanitation status index as a proxy for fecal contamination in urban Maputo, Mozambique

Sanitary surveys are used in low- and middle-income countries to assess water, sanitation, and hygiene conditions, but have rarely been compared with direct measures of environmental fecal contamination. We conducted a cross-sectional assessment of sanitary conditions and E. coli counts in soils and on surfaces of compounds (household clusters) in low-income neighborhoods of Maputo, Mozambique. We adapted the World Bank's Urban Sanitation Status Index to implement a sanitary survey tool specifically for compounds: a Localized Sanitation Status Index (LSSI) ranging from zero (poor sanitary conditions) to one (better sanitary conditions) calculated from 20 variables that characterized local sanitary conditions. We measured the variation in the LSSI with E. coli counts in soil (nine locations/compound) and surface swabs (seven locations/compound) in 80 compounds to assess reliability. Multivariable regression indicated that a ten-percentage point increase in LSSI was associated with 0.05 (95% CI: 0.00, 0.11) log10 fewer E. coli/dry gram in courtyard soil. Overall, the LSSI may be associated with fecal contamination in compound soil; however, the differences detected may not be meaningful in terms of public health hazards.

Sanitation for Low-Income Regions: A Cross-Disciplinary Review

Sanitation research focuses primarily on containing human waste and preventing disease; thus, it has traditionally been dominated by the fields of environmental engineering and public health. Over the past 20 years, however, the field has grown broader in scope and deeper in complexity, spanning diverse disciplinary perspectives. In this article, we review the current literature in the range of disciplines engaged with sanitation research in low- and middle-income countries (LMICs). We find that perspectives on what sanitation is, and what sanitation policy should prioritize, vary widely. We show how these diverse perspectives augment the conventional sanitation service chain, a framework describing the flow of waste from capture to disposal. We review how these perspectives can inform progress toward equitable sanitation for all [i.e., Sustainable Development Goal (SDG) 6]. Our key message is that both material and nonmaterial flows-and both technological and social functions-make up a sanitation "system." The components of the sanitation service chain are embedded within the flows of finance, decision making, and labor that make material flows of waste possible. The functions of capture, storage, transport, treatment, reuse, and disposal are interlinked with those of ensuring equity and affordability. We find that a multilayered understanding of sanitation, with contributions from multiple disciplines, is necessary to facilitate inclusive and robust research toward the goal of sanitation for all.

Predictors of Enteric Pathogens in the Domestic Environment from Human and Animal Sources in Rural Bangladesh

Fecal indicator organisms are measured to indicate the presence of fecal pollution, yet the association between indicators and pathogens varies by context. The goal of this study was to empirically evaluate the relationships between indicator Escherichia coli, microbial source tracking markers, select enteric pathogen genes, and potential sources of enteric pathogens in 600 rural Bangladeshi households. We measured indicators and pathogen genes in stored drinking water, soil, and on mother and child hands. Additionally, survey and observational data on sanitation and domestic hygiene practices were collected. Log10 concentrations of indicator E. coli were positively associated with the prevalence of pathogenic E. coli genes in all sample types. Given the current need to rely on indicators to assess fecal contamination in the field, it is significant that in this study context indicator E. coli concentrations, measured by IDEXX Colilert-18, provided quantitative information on the presence of pathogenic E. coli in different sample types. There were no significant associations between the human fecal marker (HumM2) and human-specific pathogens in any environmental sample type. There was an increase in the prevalence of Giardia lamblia genes, any E. coli virulence gene, and the specific E. coli virulence genes stx1/2 with every log10 increase in the concentration of the animal fecal marker (BacCow) on mothers' hands. Thus, domestic animals were important contributors to enteric pathogens in these households.

Associations between open drain flooding and pediatric enteric infections in the MAL-ED cohort in a low-income, urban neighborhood in Vellore, India

BACKGROUND

Open drains are common methods of transporting solid waste and excreta in low-income urban neighborhoods. Open drains can overflow due to blockages with solid waste and during rainfall, posing exposure risks. The goal of this study was to evaluate whether pediatric enteric infection was associated with open drains and flooding in a dense, low-income, urban neighborhood.

METHODS

As part of the MAL-ED study in Vellore, India, a cohort of 230 children provided stool specimens at 14-17 scheduled home visits and during diarrheal episodes in the first two years of life. All specimens were analyzed for enteric pathogens. Caregivers in 100 households reported on flooding of drains and households and monthly frequency of contact with open drains and flood water. Household GPS points were collected. Monthly rainfall totals for the Vellore district were collected from the Indian Meteorological Department. Clustering of reported drain and house flooding were identified by Kulldorff's Bernoulli Spatial Scan. Differences in enteric infection were assessed for household responses and spatial clusters, with interactions between reported flooding and rainfall to approximate monthly drain flooding retrospectively, using multivariable, mixed-effects logistic regression models.

RESULTS

Coverage of household toilets was low (33%), and most toilets (82%) discharged directly into open drains, suggesting poor neighborhood fecal sludge management. Odds of enteric infection increased significantly with total monthly rainfall for children who lived in households that reported that the nearby drain flooded (4% increase per cm of rain: OR: 1.04, 95% CI: 1.00-1.08) and for children in households in a downstream spatial cluster of reported drain flooding (5% increase per cm of rain: OR: 1.05, 95% CI: 1.01-1.09). There was no association between odds of enteric infection and frequency of reported contact with drain or floodwater.

CONCLUSIONS

Children in areas susceptible to open drain flooding had increased odds of enteric infection as rainfall increased. Results suggested that infection increased with rainfall due to neighborhood infrastructure (including poor fecal sludge management) and not frequency of contact. Thus, these exposures may not be mitigated by changes in personal behaviors alone. These results underscore the importance of improving the neighborhood environment to improve children's health in low-income, urban settings.

A Faecal Contamination Index for interpreting heterogeneous diarrhoea impacts of water, sanitation and hygiene interventions and overall, regional and country estimates of community sanitation coverage with a focus on low- and middle-income countries

OBJECTIVES

The impact on diarrhoea of sanitation interventions has been heterogeneous. We hypothesize that this is due to the level of prevailing faecal environmental contamination and propose a Faecal Contamination Index (FAECI) of selected WASH indicators (objective 1). Additionally, we provide estimates of the proportion of the population living in communities above certain sanitation coverage levels (objective 2).

METHODS

Objective 1: Faecal contamination post-intervention was estimated from WASH intervention reports. WASH indicators composing the FAECI included eight water, sanitation and hygiene practice indicators, which were selected for their relevance for health and data availability at study- and country-level. The association between the estimated level of faecal environmental contamination and diarrhoea was examined using meta-regression. Objective 2: A literature search was conducted to identify health-relevant community sanitation coverage thresholds. To estimate total community coverage with basic sanitation in low- and middle-income countries, at relevant thresholds, household surveys with data available at primary sampling unit (PSU)-level were analysed according to the identified thresholds, at country-, regional- and overall level.

RESULTS

Objective 1: We found a non-linear association between estimated environmental faecal contamination and sanitation interventions' impact on diarrhoeal disease. Diarrhoea reductions were highest at lower faecal contamination levels, and no diarrhoea reduction was found when contamination increased above a certain level. Objective 2: Around 45% of the population lives in communities with more than 75% of coverage with basic sanitation and 24% of the population lives in communities above 95% coverage, respectively.

CONCLUSIONS

High prevailing faecal contamination might explain interventions' poor effectiveness in reducing diarrhoea. The here proposed Faecal Contamination Index is a first attempt to estimate the level of faecal contamination in communities. Much of the world's population currently lives in faecally contaminated environments as indicated by low community sanitation coverage.

Children Are Exposed to Fecal Contamination via Multiple Interconnected Pathways: A Network Model for Exposure Assessment

In recent decades, quantitative microbial risk assessment (QMRA) has been widely used to assess exposure to fecal microbes and associated health risks. In this study, a multipathway exposure assessment model was developed to evaluate exposure to fecal microbes for children under 5 in highly contaminated urban environments. Children had contact with various environmental compartments. The contamination levels of these compartments were estimated from fecal indicator counts in the environmental samples. Structured observations of child behavior (including activities, locations, and time) were used to model behavioral sequences as a dynamic network. The exposure model combines behavior sequences with environmental contamination, using additional exposure factors when needed, to estimate the number of fecal microbes transferred from environmental sources to human oral ingestion. As fecal exposure in a highly contaminated urban environment consists of contributions from multiple pathways, it is imperative to study their relative importance. The model helps us better understand the characteristics of the exposure pathways that may be driven by variation in contamination and by variable behavior, like hygiene and high-risk activities. Importantly, the model also allows prediction of the quantitative effects of an intervention-the expected reduction in exposure due to infrastructural or behavioral changes-by means of scenario studies. Based on experience with this exposure model, we make specific recommendations for additional studies of child behavior and exposure factors in order to fill critical information gaps and improve the model structure and assumptions.

Early childhood cognitive development is affected by interactions among illness, diet, enteropathogens and the home environment: findings from the MAL-ED birth cohort study

Background

Millions of children in low-income and middle-income countries (LMICs) are at risk of not reaching their full cognitive potential. Malnutrition and enteric infections in early life are implicated as risk factors; however, most studies on these risks and their associations with cognitive development have failed to adequately account for confounding factors or the accumulation of putative insults. Here, we examine the interaction between infections and illness on cognitive development in LMIC community settings.

Methods

As part of the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) longitudinal birth cohort study, children from eight LMICs were followed from birth to 24 months to understand the influence of repeated enteric infections on child growth and development. Here, data from six sites were employed to evaluate associations between infection, illness, the home environment, micronutrient intake and status, maternal reasoning, and cognitive development at 24 months.

Results

Higher rates of enteropathogen detection and days with illness were associated with lower haemoglobin concentrations, which in turn were associated with lower cognitive scores at 24 months. Children with lower environmental health/safety scores and lower intakes of vitamin B₆ and folate had more enteropathogen detections and illness. Strength of associations varied by weight-for-age in the first 17 days of life; lower weight infants were more susceptible to the negative effects of enteropathogens and illness.

Conclusions

Enteropathogens were negatively related to child cognitive development. However, other factors were more strongly associated with child cognition. Targeting of interventions to improve cognitive development should include a focus on reducing frequency of illness, improving the safety and healthfulness of the child’s environment, and improving dietary intake.

Urban sanitation coverage and environmental fecal contamination: Links between the household and public environments of Accra, Ghana

Exposure to fecal contamination in public areas, especially in dense, urban environments, may significantly contribute to enteric infection risk. This study examined associations between sanitation and fecal contamination in public environments in four low-income neighborhoods in Accra, Ghana. Soil (n = 72) and open drain (n = 90) samples were tested for E. coli, adenovirus, and norovirus. Sanitation facilities in surveyed households (n = 793) were categorized by onsite fecal sludge containment ("contained" vs. "uncontained") using previous Joint Monitoring Program infrastructure guidelines. Most sanitation facilities were shared by multiple households. Associations between spatial clustering of household sanitation coverage and fecal contamination were examined, controlling for neighborhood and population density (measured as enumeration areas in the 2010 census and spatially matched to sample locations). E. coli concentrations in drains within 50m of clusters of contained household sanitation were more than 3 log-units lower than those outside of clusters. Further, although results were not always statistically significant, E. coli concentrations in drains showed consistent trends with household sanitation coverage clusters: concentrations were lower in or near clusters of high coverage of household sanitation facilities-especially contained facilities-and vice versa. Virus detection in drains and E. coli concentrations in soil were not significantly associated with clustering of any type of household sanitation and did not exhibit consistent trends. Population density alone was not significantly associated with any of the fecal contamination outcomes by itself and was a significant, yet inconsistent, effect modifier of the association between sanitation clusters and E. coli concentrations. These findings suggest clustering of contained household sanitation, even when shared, may be associated with lower levels of fecal contamination within drains in the immediate public domain. Further research is needed to better quantify these relationships and examine impacts on health.

Child soil ingestion in rural Ghana - frequency, caregiver perceptions, relationship with household floor material and associations with child diarrhoea

OBJECTIVES

The objectives of this work were to evaluate (i) the prevalence and frequency of caregiver-reported soil ingestion by children, (ii) whether household flooring material in the bedroom (earth vs. concrete) affected caregiver-reported soil ingestion, (iii) whether caregiver-reported soil ingestion was associated with caregiver-reported diarrhoea and (iv) caregivers' perceptions of their children ingesting soil.

METHODS

We conducted 309 household surveys in northern Ghana, including 529 children under five (249 children aged 6-36 months), and measured faecal contamination in soil from 31 households.

RESULTS

Among all children, 15% were reported to have directly ingested soil in the past week, including 28% of children aged 6-36 months. Among children reported to have ingested soil, the median frequency was 14 times in the past week, and the median amount of soil ingested each time was half a handful. There was no association between household floor material and whether the caregiver observed a child directly ingesting soil. After adjusting for household floor material and other potential confounding variables, caregiver-reported soil ingestion was associated with caregiver-reported diarrhoea for children under five [adjusted odds ratio (adj. OR) = 3.13, 95% confidence interval (CI) 2.76-3.55] and children aged 6-36 months (adj. OR = 2.61, 95% CI 2.01-3.39). Approximately 83% of caregivers whose children ingested soil reported they thought it was unsafe and were more likely to report stopping their child from ingesting soil, but these responses did not affect the quantity of soil ingested.

CONCLUSIONS

Our results suggest direct soil ingestion is associated with diarrhoea independent of household floor material, and separate interventions may be necessary to prevent exploratory soil ingestion.

Faecal Pathogen Flows and Their Public Health Risks in Urban Environments: A Proposed Approach to Inform Sanitation Planning

Public health benefits are often a key political driver of urban sanitation investment in developing countries, however, pathogen flows are rarely taken systematically into account in sanitation investment choices. While several tools and approaches on sanitation and health risks have recently been developed, this research identified gaps in their ability to predict faecal pathogen flows, to relate exposure risks to the existing sanitation services, and to compare expected impacts of improvements. This paper outlines a conceptual approach that links faecal waste discharge patterns with potential pathogen exposure pathways to quantitatively compare urban sanitation improvement options. An illustrative application of the approach is presented, using a spreadsheet-based model to compare the relative effect on disability-adjusted life years of six sanitation improvement options for a hypothetical urban situation. The approach includes consideration of the persistence or removal of different pathogen classes in different environments; recognition of multiple interconnected sludge and effluent pathways, and of multiple potential sites for exposure; and use of quantitative microbial risk assessment to support prediction of relative health risks for each option. This research provides a step forward in applying current knowledge to better consider public health, alongside environmental and other objectives, in urban sanitation decision making. Further empirical research in specific locations is now required to refine the approach and address data gaps.

Multipathway Quantitative Assessment of Exposure to Fecal Contamination for Young Children in Low-Income Urban Environments in Accra, Ghana: The SaniPath Analytical Approach

Lack of adequate sanitation results in fecal contamination of the environment and poses a risk of disease transmission via multiple exposure pathways. To better understand how eight different sources contribute to overall exposure to fecal contamination, we quantified exposure through multiple pathways for children under 5 years old in four high-density, low-income, urban neighborhoods in Accra, Ghana. We collected more than 500 hours of structured observation of behaviors of 156 children, 800 household surveys, and 1,855 environmental samples. Data were analyzed using Bayesian models, estimating the environmental and behavioral factors associated with exposure to fecal contamination. These estimates were applied in exposure models simulating sequences of behaviors and transfers of fecal indicators. This approach allows us to identify the contribution of any sources of fecal contamination in the environment to child exposure and use dynamic fecal microbe transfer networks to track fecal indicators from the environment to oral ingestion. The contributions of different sources to exposure were categorized into four types (high/low by dose and frequency), as a basis for ranking pathways by the potential to reduce exposure. Although we observed variation in estimated exposure (108-1016 CFU/day for Escherichia coli) between different age groups and neighborhoods, the greatest contribution was consistently from food (contributing > 99.9% to total exposure). Hands played a pivotal role in fecal microbe transfer, linking environmental sources to oral ingestion. The fecal microbe transfer network constructed here provides a systematic approach to study the complex interaction between contaminated environment and human behavior on exposure to fecal contamination.