Occurrence of Host-Associated Fecal Markers on Child Hands, Household Soil, and Drinking Water in Rural Bangladeshi Households

Rural revival: Navigating environmental engineering and technology

The necessity for global engineering and technological solutions to address rural environmental challenges is paramount, particularly in improving rural waste treatment and infrastructure. This study presents a comprehensive quantitative analysis of 3901 SCI/SSCI and 3818 Chinese CSCD papers, spanning from 1989 to 2021, using tools like Derwent Data Analyzer and VOSviewer. Our key findings reveal a significant evolution in research focus, including a 716.67% increase in global publications from 1995 to 2008 and a 154.76% surge from 2015 to 2021, highlighting a growing research interest with technological hotspots in rural revitalization engineering and agricultural waste recycling. China and the USA are pivotal, contributing 784 and 714 publications respectively. Prominent institutions such as the Chinese Academy of Sciences play a crucial role, particularly in fecal waste treatment technology. These insights advocate for enhanced policy development and practical implementations to foster inclusive and sustainable rural environments globally.

Addressing Fecal Contamination in Rural Kenyan Households: The Roles of Environmental Interventions and Animal Ownership

Combined water, sanitation, and handwashing (WSH) interventions could reduce fecal contamination along more transmission pathways than single interventions alone. We measured Escherichia coli levels in 3909 drinking water samples, 2691 child hand rinses, and 2422 toy ball rinses collected from households enrolled in a 2-year cluster-randomized controlled trial evaluating single and combined WSH interventions. Water treatment with chlorine reduced E. coli in drinking water. A combined WSH intervention improved water quality by the same magnitude but did not affect E. coli levels on hands or toys. One potential explanation for the limited impact of the sanitation intervention (upgraded latrines) is failure to address dog and livestock fecal contamination. Small ruminant (goat or sheep) ownership was associated with increased E. coli levels in stored water and on child hands. Cattle and poultry ownership was protective against child stunting, and domesticated animal ownership was not associated with child diarrhea. Our findings do not support restricting household animal ownership to prevent child diarrheal disease or stunting but do support calls for WSH infrastructure that can more effectively reduce household fecal contamination.

Is detection of enteropathogens and human or animal faecal markers in the environment associated with subsequent child enteric infections and growth: an individual participant data meta-analysis

BACKGROUND

Quantifying contributions of environmental faecal contamination to child diarrhoea and growth faltering can illuminate causal mechanisms behind modest health benefits in recent water, sanitation, and hygiene (WASH) trials. We aimed to assess associations between environmental detection of enteropathogens and human or animal microbial source tracking markers (MSTM) and subsequent child health outcomes.

METHODS

In this individual participant data meta-analysis we searched we searched PubMed, Embase, CAB Direct Global Health, Agricultural and Environmental Science Database, Web of Science, and Scopus for WASH intervention studies with a prospective design and concurrent control that measured enteropathogens or MSTM in environmental samples, or both, and subsequently measured enteric infections, diarrhoea, or height-for-age Z-scores (HAZ) in children younger than 5 years. We excluded studies that only measured faecal indicator bacteria. The initial search was done on Jan 19, 2021, and updated on March 22, 2023. One reviewer (AM) screened abstracts, and two independent reviewers (AM and RT) examined the full texts of short-listed articles. All included studies include at least one author that also contributed as an author to the present Article. Our primary outcomes were the 7-day prevalence of caregiver-reported diarrhoea and HAZ in children. For specific enteropathogens in the environment, primary outcomes also included subsequent child infection with the same pathogen ascertained by stool testing. We estimated associations using covariate-adjusted regressions and pooled estimates across studies.

FINDINGS

Data from nine published reports from five interventions studies, which included 8603 children (4302 girls and 4301 boys), were included in the meta-analysis. Environmental pathogen detection was associated with increased infection prevalence with the same pathogen and lower HAZ (ΔHAZ -0·09 [95% CI -0·17 to -0·01]) but not diarrhoea (prevalence ratio 1·22 [95% CI 0·95 to 1·58]), except during wet seasons. Detection of MSTM was not associated with diarrhoea (no pooled estimate) or HAZ (ΔHAZ -0·01 [-0·13 to 0·11] for human markers and ΔHAZ -0·02 [-0·24 to 0·21] for animal markers). Soil, children's hands, and stored drinking water were major transmission pathways.

INTERPRETATION

Our findings support a causal chain from pathogens in the environment to infection to growth faltering, indicating that the lack of WASH intervention effects on child growth might stem from insufficient reductions in environmental pathogen prevalence. Studies measuring enteropathogens in the environment should subsequently measure the same pathogens in stool to further examine theories of change between WASH, faecal contamination, and health. Given that environmental pathogen detection was predictive of infection, programmes targeting specific pathogens (eg, vaccinations and elimination efforts) can environmentally monitor the pathogens of interest for population-level surveillance instead of collecting individual biospecimens.

FUNDING

The Bill & Melinda Gates Foundation and the UK Foreign and Commonwealth Development Office.

Prevention of human exposure to livestock faecal waste in the household: a scoping study of interventions conducted in sub-Saharan Africa

BACKGROUND

Poorly managed animal faecal waste can result in detrimental environmental and public health implications. Limiting human exposure to animal waste through Animal inclusive Water Sanitation and Hygiene (A-WASH) strategies is imperative to improve public health in livestock keeping households but has received little attention to date. A small number of A-WASH interventions have previously been identified through a systematic review by another research team, and published in 2017. To inform intervention design with the most up-to-date information, a scoping study was conducted to map the existing evidence for A-WASH in sub-Saharan Africa (SSA) emerging since the previous review.

METHODS

This review followed PRISMA guidelines to identify interventions in SSA published between January 2016 to October 2022. Databases searched included PubMed, PMC Europe, CabDirect and Web of Science. Studies were eligible for inclusion if they were written in English and documented interventions limiting human contact with animal faecal material in the SSA context. Key data extracted included: the intervention itself, its target population, cost, measure of effectiveness, quantification of effect, assessment of success, acceptability and limitations. These data were synthesized into a narrative, structured around the intervention type.

FINDINGS

Eight eligible articles were identified. Interventions to reduce human exposure to animal faecal matter were conducted in combination with 'standard' human-centric WASH practices. Identified interventions included the management of human-animal co-habitation, educational programs and the creation of child-safe spaces. No novel A-WASH interventions were identified in this review, beyond those identified by the review in 2017. Randomised Controlled Trials (RCTs) were used to evaluate six of the eight identified interventions, but as effect was evaluated through various measures, the ability to formally compare efficacy of interventions is lacking.

CONCLUSION

This study indicates that the number of A-WASH studies in SSA is increasing and the use of RCTs suggests a strong desire to create high-quality evidence within this field. There is a need for standardisation of effect measures to enable meta-analyses to be conducted to better understand intervention effectiveness. Evaluation of scalability and sustainability of interventions is still lacking in A - WASH research.

The effect of a health extension program on improving water, sanitation, and hygiene practices in rural Ethiopia

BACKGROUND

To make basic primary health care services accessible, especially to the rural community, the government of Ethiopia launched the Health Extension Program (HEP) in 2004. Most of components of HEP are dedicated to hygiene and sanitation. Few studies have assessed the role of the Health Extension Program in improving water, hygiene, and sanitation (WASH) practices in Ethiopia. This study explored the role of health extension workers (HEWs) in influencing household water treatment practices, latrine ownership, latrine use and ownership, and the use of hand-washing facilities on the incidence of diarrheal diseases among the children under five years of age in rural Ethiopia.

METHODS

Using a cross sectional design, we conducted a national assessment that covered all nine regions of Ethiopia. We conducted face-to-face interviews among a sample of 6430 rural households using a structured questionnaire and an observation checklist to collect data from March 2018 to May 2019. Multilevel logistic regressions models were used to determine the relationships between the exposure of households to HEWs and WASH practice outcomes such as the use of water from an improved water source, household water treatment practices, availability of hand-washing and hand-washing with soap and water, availability of latrines, and use of latrines as well as the incidence of diarrheal diseases among children age 5 and younger. Our models were adjusted for covariates and confounders and P-values less than 5% were set to determine statistical significance.

RESULTS

We found that 72.7% of rural households had some type of latrine and 27.3% reported practicing open defecation. A total of 71.5% of rural households had access to drinking water from improved water sources, but only 9.4% reported practicing household water treatment. Exposure to HEWs was positively associated with household water treatment practices (AOR: 1.46; 95% CI = 1.01-2.10) and latrine availability (AOR: 1.44; 95% CI = 1.15-1.80). Among the households who were either visited by HEWs at their home or the that visited health posts to meet with the HEWs, being exposed to WASH health education by HEWs was significantly associated with the availability of a hand-washing facility (AOR: 5.14; 95% CI = 4.11-6.42) and latrine availability (AOR: 1.48; 95% CI = 1.10-2.01). However, we did not find a relationship between the incidence of diarrhea among children age 5 and under and exposure to HEWs (AOR: 2.09; 95% CI = 0.73- 6.62).

CONCLUSION

Our results show a significant association between exposure to the Health Extension Program/ HEWs and improved household water treatment practices, latrine construction, and the availability of hand-washing facilities in rural Ethiopia, suggesting the need to strengthen efforts to change WASH behavior through the Heath Extension Program. On the other hand, further investigation is needed regarding the spillover effect of latrine use practices and the reduction of the incidence of diarrheal diseases.

Effects of water, sanitation, and hygiene interventions on detection of enteropathogens and host-specific faecal markers in the environment: a systematic review and individual participant data meta-analysis

BACKGROUND

Water, sanitation, and hygiene (WASH) improvements are promoted to reduce diarrhoea in low-income countries. However, trials from the past 5 years have found mixed effects of household-level and community-level WASH interventions on child health. Measuring pathogens and host-specific faecal markers in the environment can help investigate causal pathways between WASH and health by quantifying whether and by how much interventions reduce environmental exposure to enteric pathogens and faecal contamination from human and different animal sources. We aimed to assess the effects of WASH interventions on enteropathogens and microbial source tracking (MST) markers in environmental samples.

METHODS

We did a systematic review and individual participant data meta-analysis, which included searches from Jan 1, 2000, to Jan 5, 2023, from PubMed, Embase, CAB Direct Global Health, Agricultural and Environmental Science Database, Web of Science, and Scopus, of prospective studies with water, sanitation, or hygiene interventions and concurrent control group that measured pathogens or MST markers in environmental samples and measured child anthropometry, diarrhoea, or pathogen-specific infections. We used covariate-adjusted regression models with robust standard errors to estimate study-specific intervention effects and pooled effect estimates across studies using random-effects models.

FINDINGS

Few trials have measured the effect of sanitation interventions on pathogens and MST markers in the environment and they mostly focused on onsite sanitation. We extracted individual participant data on nine environmental assessments from five eligible trials. Environmental sampling included drinking water, hand rinses, soil, and flies. Interventions were consistently associated with reduced pathogen detection in the environment but effect estimates in most individual studies could not be distinguished from chance. Pooled across studies, we found a small reduction in the prevalence of any pathogen in any sample type (pooled prevalence ratio [PR] 0·94 [95% CI 0·90-0·99]). Interventions had no effect on the prevalence of MST markers from humans (pooled PR 1·00 [95% CI 0·88-1·13]) or animals (pooled PR 1·00 [95% CI 0·97-1·03]).

INTERPRETATION

The small effect of these sanitation interventions on pathogen detection and absence of effects on human or animal faecal markers are consistent with the small or null health effects previously reported in these trials. Our findings suggest that the basic sanitation interventions implemented in these studies did not contain human waste and did not adequately reduce exposure to enteropathogens in the environment.

FUNDING

Bill and Melinda Gates Foundation and the UK Foreign and Commonwealth Development Office.

Human Colonization with Antibiotic-Resistant Bacteria from Nonoccupational Exposure to Domesticated Animals in Low- and Middle-Income Countries: A Critical Review

Data on community-acquired antibiotic-resistant bacterial infections are particularly sparse in low- and middle-income countries (LMICs). Limited surveillance and oversight of antibiotic use in food-producing animals, inadequate access to safe drinking water, and insufficient sanitation and hygiene infrastructure in LMICs could exacerbate the risk of zoonotic antibiotic resistance transmission. This critical review compiles evidence of zoonotic exchange of antibiotic-resistant bacteria (ARB) or antibiotic resistance genes (ARGs) within households and backyard farms in LMICs, as well as assesses transmission mechanisms, risk factors, and environmental transmission pathways. Overall, substantial evidence exists for exchange of antibiotic resistance between domesticated animals and in-contact humans. Whole bacteria transmission and horizontal gene transfer between humans and animals were demonstrated within and between households and backyard farms. Further, we identified water, soil, and animal food products as environmental transmission pathways for exchange of ARB and ARGs between animals and humans, although directionality of transmission is poorly understood. Herein we propose study designs, methods, and topical considerations for priority incorporation into future One Health research to inform effective interventions and policies to disrupt zoonotic antibiotic resistance exchange in low-income communities.

Exploring the determinants and indicators of poultry feces management behaviors in rural Western Uganda

Animal ownership has reported financial and nutritional benefits but has also been associated with enteric and respiratory infections, and inadequate sanitation and hygiene can lead to children touching and ingesting animal fecal matter. We identified key indicators for poultry feces management and investigated their social determinants using data from a baseline survey of a randomized-controlled trial of a poultry management training program in rural Western Uganda. The baseline survey was conducted in the Masindi and Kiryandongo districts of Uganda in September 2019, and data collected from 609 households were used. We evaluated indicators for poultry feces management behaviors using scale development methods, including descriptive statistics, bivariate correlation analyses, and Factor Analysis of Mixed Data. We also investigated social determinants of key poultry feces management behaviors using logistic and multinomial logistic regression models. A significant increase in odds of having free-roaming poultry was found for each additional poultry owned (OR = 1.18, P < 0.001). The odds of a household having an observed enclosure for poultry increased by 5% with each incremental poultry owned (OR = 1.05, P < 0.001), and by 4% with increasing wealth with each additional point on the poverty probability index score (OR = 1.04, P < 0.001). Our results also suggest enclosures are intermittently used and constructing them without further intervention likely will not be sufficient for effectively managing animal fecal contamination. We recommend that future studies on animal feces management measure indicators for corralling and feces disposal practices and evaluate their relationship to enteric pathogen exposure and health outcomes. Insights from this work can inform the development of robust indicators of poultry feces management behaviors that can be used for monitoring and evaluation purposes.

Differential Overlap in Human and Animal Fecal Microbiomes and Resistomes in Rural versus Urban Bangladesh

While the development of antibiotic resistance in animal gut microbiomes and subsequent transmission to humans has been demonstrated in intensive farming environments and high-income countries, evidence of zoonotic exchange of antibiotic resistance in LMIC communities is lacking. This research provides genomic evidence of overlap of antibiotic resistance genes between humans and animals, especially in urban communities, and highlights chickens as important reservoirs of antibiotic resistance.

Effects of local handwashing agents on microbial contamination of the hands in a rural setting in Northwest Ethiopia: a cluster randomised controlled trial

OBJECTIVE

To evaluate the effectiveness of handwashing with water and wood ash in reducing faecal contamination of the hands.

DESIGN

A cluster randomised controlled trial was employed with two arms: handwashing with water and wood ash versus handwashing with water alone.

SETTING

Rural households of East Dembiya District, Central Gondar Zone, Amhara National Regional State, Ethiopia.

PARTICIPANTS

440 mothers and caregivers of children younger than 5 years assigned (1:1, 220 in each group) in clusters, with buffer zones between each cluster.

INTERVENTION

Health education on effective handwashing was given to the intervention and control groups. Participants in the intervention group used wood ash of the same quantity (ie, one closed palm).

OUTCOME MEASURES

The primary outcome was microbial contamination of the hands, measured by means of Escherichia coli counts before and after handwashing.

RESULTS

At baseline, 75.9% and 67.7% of the participants in the intervention and control groups, respectively, had dirt on their fingernails, and the hands of all participants in both groups were contaminated with E. coli. The mean E. coli counts recovered at baseline were 3.07 log10 colony forming unit (CFU)/swab in the intervention group and 3.03 log10 CFU/swab in the control group, while at endline it was 1.4 log10 CFU/swab in the intervention group and 3.02 log10 CFU/swab in the control group. The mean E.coli counts was reduced by 1.65 log10 due to the intervention (difference-in-differences: β= -1.65, 95% CI= -1.84 to -1.46).

CONCLUSION

Two-thirds of the swab samples tested positive for E. coli after handwashing with water and wood ash, which indicates wood ash is not very effective in terms of completely removing micro-organisms on the hands. However, wood ash was significantly better than water alone in reducing the concentration of faecal coliform organisms on the hands. Local health authorities should primarily promote handwashing with soap. However, in the absence of soap, use of wood ash over water alone might be appropriate.

TRIAL REGISTRATION NUMBER

PACTR202011855730652.

Determinants of Pathogen Contamination of the Environment in the Greater Yangon Area, Myanmar

Recent results from water, sanitation, and hygiene interventions highlight the need to better understand environmental influences on enteropathogen transmission. We quantified a range of viral, bacterial, and protozoal pathogens and one indicator, Enterococcus faecalis in soil and water from urban and rural sites in and around Yangon, Myanmar. We found that environmental characteristics associated with contamination differed by pathogens and substrates. In soil, bacterial pathogen gene counts were associated with elevation and drainage ditches (compared to stagnant water) (RR = 0.96, 95% CI 0.93, 0.99 and RR = 1.70, 95% CI 1.18, 2.45, respectively), while viral gene counts were associated with the presence of sanitation facilities within 50 m of the collection point (RR = 3.99, 95% CI 1.12, 14.24). In water, E. faecalis, total pathogen, and bacterial pathogen gene counts were associated with drainage ditches (RR = 1.86, 95% CI 1.27, 2.72, RR = 1.38 95% CI 1.09, 1.74, and RR = 1.38 95% CI 1.07, 1.77, respectively). E. faecalis, total pathogen, bacterial pathogen, and viral gene counts were associated with the presence of uncollected garbage within 50 m of the collection point (RR = 1.57, 95% CI 1.00, 2.47, RR = 1.52, 95% CI 1.16, 2.00, RR = 1.52, 95% CI 1.13, 2.06, and RR = 1.75, 95% CI 1.17, 2.61 respectively). Measuring the environment provides added specificity toward identifying important environmental pathways that require mitigation.

Identifying Inorganic Turbidity in Water Samples as Potential Loss Factor During Nucleic Acid Extraction: Implications for Molecular Fecal Pollution Diagnostics and Source Tracking

Molecular diagnostic methods are increasingly applied for food and environmental analysis. Since several steps are involved in sample processing which can affect the outcome (e.g., adhesion of DNA to the sample matrix, inefficient precipitation of DNA, pipetting errors and (partial) loss of the DNA pellet during DNA isolation), quality control is essential at all processing levels. In soil microbiology, particular attention has been paid to the inorganic component of the sample matrix affecting DNA extractability. In water quality testing, however, this aspect has mostly been neglected so far, although it is conceivable that these mechanisms have a similar impact. The present study was therefore dedicated to investigate possible matrix effects on results of water quality analysis. Field testing in an aquatic environment with pronounced chemo-physical gradients [total suspended solids (TSS), inorganic turbidity, total organic carbon (TOC), and conductivity] indicated a negative association between DNA extractability (using a standard phenol/chloroform extraction procedure) and turbidity (spearman ρ = −0.72, p < 0.001, n = 21). Further detailed laboratory experiments on sediment suspensions confirmed the hypothesis of inorganic turbidity being the main driver for reduced DNA extractability. The observed effects, as known from soil samples, were also indicated to result from competitive effects for free charges on clay minerals, leading to adsorption of DNA to these inorganic particles. A protocol modification by supplementing the extraction buffer with salmon sperm DNA, to coat charged surfaces prior to cell lysis, was then applied on environmental water samples and compared to the standard protocol. At sites characterized by high inorganic turbidity, DNA extractability was significantly improved or made possible in the first place by applying the adapted protocol. This became apparent from intestinal enterococci and microbial source tracking (MST)-marker levels measured by quantitative polymerase chain reaction (qPCR) (100 to 10,000-fold median increase in target concentrations). The present study emphasizes the need to consider inorganic turbidity as a potential loss factor in DNA extraction from water-matrices. Negligence of these effects can lead to a massive bias, by up to several orders of magnitude, in the results of molecular MST and fecal pollution diagnostics.

Progress in Water, Sanitation and Hygiene (WASH) coverage and potential contribution to the decline in diarrhea and stunting in Ethiopia

Inadequate safe water supply and poor sanitation and hygiene continue to be important risk factors for diarrhoea and stunting globally. We used data from the four rounds of the Ethiopian Demographic and Health Survey and applied the new World Health Organization (WHO)/UNICEF Joint Monitoring Program (JMP) service standards to assess progress in water, sanitation and hygiene (WASH) coverage between 2000 and 2016. We also performed an age-disaggregated pooled linear probability regression analysis followed by a decomposition analysis to determine whether changes in WASH practices have contributed to the changing prevalence of diarrhoea and stunting in children under 5 years of age. We observed a significant increase in the coverage of safe drinking water and adequate sanitation facilities over the period. At the national level, the use of a basic water source increased from 18% in 2000 to 50% in 2016. Open defecation declined from 82% to 32% over the same period. However, in 2016, only 6% of households had access to a basic sanitation facility, and 40% of households had no handwashing facilities. The reduction in surface water use between 2000 and 2016 explained 6% of the decline in diarrhoea observed among children aged 0-5 months. In children aged 6-59 months, between 7% and 9% of the reduction in stunting were attributable to the reduction in open defecation over this period. Despite progress, improvements are still needed to increase basic WASH coverage in Ethiopia. Our findings showed that improvements in water and sanitation only modestly explained reductions in diarrhoea and stunting.

The occurrence and control of waterborne viruses in drinking water treatment: A review

As the coronavirus disease 2019 continues to spread globally, its culprit, the severe acute respiratory syndrome coronavirus 2 has been brought under scrutiny. In addition to inhalation transmission, the possible fecal-oral viral transmission via water/wastewater has also been brought under the spotlight, necessitating a timely global review on the current knowledge about waterborne viruses in drinking water treatment system - the very barrier that intercepts waterborne pathogens to terminal water users. In this article we reviewed the occurrence, concentration methods, and control strategies, also, treatment performance on waterborne viruses during drinking water treatment were summarized. Additionally, we emphasized the potential of applying the quantitative microbial risk assessment to guide drinking water treatment to mitigate the viral exposure risks, especially when the unregulated novel viral pathogens are of concern. This review paves road for better control of viruses at drinking water treatment plants to protect public health.

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.

Longitudinal Effects of a Sanitation Intervention on Environmental Fecal Contamination in a Cluster-Randomized Controlled Trial in Rural Bangladesh

Household latrine access generally is not associated with reduced fecal contamination in the environment, but its long-term effectiveness has not been measured. We conducted an environmental assessment nested within the WASH Benefits Bangladesh randomized controlled trial (NCT01590095). We quantified E. coli and fecal coliforms in samples of stored drinking water, child hands, mother hands, soil, and food among a random sample of households from the sanitation and control arms of the trial. Samples were collected during eight quarterly visits approximately 1-3.5 years after intervention initiation. Overall, there were no substantial differences in environmental fecal contamination between households enrolled in the sanitation and control arms. Statistically significant reductions were found in stored water and child hands after pooling across sampling rounds, but the effects were small and not consistent across rounds. In addition, we assessed potential effect modification of intervention effects by follow-up time, season, wealth, community-level latrine density and coverage, population density, and domestic animal ownership. While the intervention had statistically significant effects within some subgroups, there were no consistent patterns of effect modification. Our findings support a growing consensus that on-site latrines are insufficient to prevent fecal contamination in the rural household environment.

Longitudinal Monitoring of SARS-CoV-2 RNA on High-Touch Surfaces in a Community Setting

Environmental surveillance of surface contamination is an unexplored tool for understanding transmission of SARS-CoV-2 in community settings. We conducted longitudinal swab sampling of high-touch non-porous surfaces in a Massachusetts town during a COVID-19 outbreak from April to June 2020. Twenty-nine of 348 (8.3%) surface samples were positive for SARS-CoV-2 RNA, including crosswalk buttons, trash can handles, and door handles of essential business entrances (grocery store, liquor store, bank, and gas station). The estimated risk of infection from touching a contaminated surface was low (less than 5 in 10,000) by quantitative microbial risk assessment, suggesting fomites play a minimal role in SARS-CoV-2 community transmission. The weekly percentage of positive samples (out of n = 33 unique surfaces per week) best predicted variation in city-level COVID-19 cases with a 7-day lead time. Environmental surveillance of SARS-CoV-2 RNA on high-touch surfaces may be a useful tool to provide early warning of COVID-19 case trends.

Associations among Household Animal Ownership, Infrastructure, and Hygiene Characteristics with Source Attribution of Household Fecal Contamination in Peri-Urban Communities of Iquitos, Peru

Using previously validated microbial source tracking markers, we detected and quantified fecal contamination from avian species and avian exposure, dogs, and humans on household cooking tables and floors. The association among contamination, infrastructure, and socioeconomic covariates was assessed using simple and multiple ordinal logistic regressions. The presence of Campylobacter spp. in surface samples was linked to avian markers. Using molecular methods, animal feces were detected in 75.0% and human feces in 20.2% of 104 households. Floors were more contaminated than tables as detected by the avian marker Av4143, dog marker Bactcan, and human marker Bachum. Wood tables were consistently more contaminated than non-wood surfaces, specifically with the mitochondrial avian markers ND5 and CytB, fecal marker Av4143, and canine marker Bactcan. Final multivariable models with socioeconomic and infrastructure characteristics included as covariates indicate that detection of avian feces and avian exposure was associated with the presence of chickens, maternal age, and length of tenancy, whereas detection of human markers was associated with unimproved water source. Detection of Campylobacter in surface samples was associated with the avian fecal marker Av4143. We highlight the critical need to detect and measure the burden of animal fecal waste when evaluating household water, hygiene, and sanitation interventions, and the possibility of decreasing risk of exposure through the modification of surfaces to permit more effective household disinfection practices. Animals may be a more important source of household fecal contamination than humans in many low-resource settings, although interventions have historically focused almost exclusively on managing human waste.

Can breastfeeding protect against antimicrobial resistance?

BACKGROUND

The proportion of infections among young children that are antimicrobial-resistant is increasing across the globe. Newborns may be colonized with enteric antimicrobial-resistant pathogens early in life, which is a risk factor for infection-related morbidity and mortality. Breastfeeding is actively promoted worldwide for its beneficial impacts on newborn health and gut health. However, the role of breastfeeding and human milk components in mitigating young children's carriage of antimicrobial-resistant pathogens and antibiotic resistance genes has not been comprehensively explored.

MAIN BODY

Here, we review how the act of breastfeeding, early breastfeeding, and/or human milk components, such as the milk microbiota, secretory IgA, human milk oligosaccharides, antimicrobial peptides, and microRNA -bearing extracellular vesicles, could play a role in preventing the establishment of antimicrobial-resistant pathogens in young children's developing gut microbiomes. We describe findings from recent human studies that support this concept.

CONCLUSION

Given the projected rise in global morbidity and mortality that will stem from antimicrobial-resistant infections, identifying behavioral or nutritional interventions that could decrease children's susceptibility to colonization with antimicrobial-resistant pathogens may be one strategy for protecting their health. We suggest that breastfeeding and human milk supplements deserve greater attention as potential preventive measures in the global effort to combat antimicrobial resistance, particularly in low- and middle-income settings.

Shared bacterial communities between soil, stored drinking water, and hands in rural Bangladeshi households

Understanding household-level transmission pathways of fecal pathogens can provide insight for developing effective strategies to reduce diarrheal illness in low- and middle-income countries. We applied whole bacterial community analysis to investigate pathways of bacterial transmission in 50 rural Bangladeshi households. SourceTracker was used to quantify the shared microbial community in household reservoirs (stored drinking water, soil, and hands) and estimate the percentage of fecal-associated bacteria from child and mothers' feces in these reservoirs. Among the reservoirs studied, most bacterial transfer occurred between mothers' and children's hands and between mothers' hands and stored water. The relative percentage of human fecal-associated bacteria in all household reservoirs was low. We also quantified the number of identical amplicon sequence variants within and between individual households to assess bacterial community exchange in the domestic environment. Intra-household sharing of bacteria between mothers' and children's hands and between hands and soil was significantly greater than inter-household sharing.

CrAssphage for fecal source tracking in Chile: Covariation with norovirus, HF183, and bacterial indicators

Anthropogenic fecal pollution in urban waterbodies can promote the spread of waterborne disease. The objective of this study was to test crAssphage, a novel viral human fecal marker not previously applied for fecal source tracking in Latin America, as a fecal pollution marker in an urban river in Chile. Human fecal markers crAssphage CPQ_064 and Bacteroides HF183, the human pathogen norovirus GII, and culturable fecal indicator bacteria (FIB) were quantified at six locations spanning reaches of the Mapocho River from upstream to downstream of Santiago, as well as in repeated sub-daily frequency samples at two urban locations. Norovirus showed positive correlation trends with crAssphage (τ = 0.57, p = 0.06) and HF183 (τ = 0.64, p = 0.03) in river water, but not with E. coli or enterococci. CrAssphage and HF183 concentrations were strongly linearly related (slope = 0.97, p < 0.001). Chlorinated wastewater effluent was an important source of norovirus GII genes to the Mapocho. Precipitation showed non-significant positive relationships with human and general fecal indicators. Concentrations of crAssphage and HF183 in untreated sewage were 8.35 and 8.07 log₁₀ copy/100 ml, respectively. Preliminary specificity testing did not detect crAssphage or HF183 in bird or dog feces, which are predominant non-human fecal sources in the urban Mapocho watershed. This study is the first to test crAssphage for microbial source tracking in Latin America, provides insight into fecal pollution dynamics in a highly engineered natural system, and indicates river reaches where exposure to human fecal pollution may pose a public health risk.

Validation of microbial source tracking markers for the attribution of fecal contamination in indoor-household environments of the Peruvian Amazon

The performance of eight microbial source tracking (MST) markers was evaluated in a low-resource, tropical community located in Iquitos, Peru. Fecal samples from humans, dogs, cats, rats, goats, buffalos, guinea-pigs, chickens, ducks, pigeons, and parrots were collected (n = 117). All samples were tested with human (BacHum, HF183-Taqman), dog (BactCan), pig (Pig-2-Bac), and avian (LA35, Av4143, ND5, cytB) markers using quantitative PCR (qPCR). Internal validity metrics were calculated using all animal fecal samples, as well as animal fecal samples contextually relevant for the Peruvian Amazon. Overall, Pig-2-Bac performed best, with 100% sensitivity and 88.5% specificity to detect the correct fecal source. Human-associated markers showed a sensitivity of 80.0% and 76.7%, and specificity of 66.2% and 67.6%. When limiting the analysis to contextually relevant animal fecal samples for the Peruvian Amazon, Av143 surpassed cytB with 95.7% sensitivity and 81.8% specificity. BactCan demonstrated 100% sensitivity and 47.4% specificity. The gene copy number detected by BacHum and HF183-Taqman were positively correlated (Pearson's correlation coefficient: 0.785), as well as avian markers cytB with Av4143 (Pearson's correlation coefficient: 0.508) and nd5 (Pearson's correlation coefficient: 0.949). These findings suggest that markers such as Av4143, Pig2Bac, cytb and BacHum have acceptable performance to be impactful in source attribution studies for zoonotic enteric disease transmission in this and similar low-resource communities.

Child hand contamination is associated with subsequent pediatric diarrhea in rural Democratic Republic of the Congo (REDUCE Program)

OBJECTIVE

The Reducing Enteropathy, Undernutrition, and Contamination in the Environment (REDUCE) program focuses on identifying exposure pathways to faecal pathogens for young children in the Democratic Republic of the Congo (DRC) and on developing scalable interventions to reduce faecal contamination from these pathways.

METHODS

A prospective cohort study of 690 participants was conducted to investigate the association between hand, food, and environmental faecal contamination and diarrhoeal disease prevalence among young children in Walungu Territory, South Kivu, DRC. A total of 1923 hand rinse, soil, food, object, surface, stored water and water source samples were collected during unannounced spot checks after baseline enrolment and analysed for Escherichia coli. Caregiver reports of diarrhoea were obtained from children < 5 years at a 6-month follow-up.

RESULTS

E.coli was detected in 73% of child and caregiver hand-rinse samples, 69% of soil samples from child play spaces, 54% of child food samples, 38% of objects and surfaces children were observed putting in their mouths, 74% of stored water samples, and 40% of source water samples. Children < 5 years with E. coli on their hands had significantly higher odds of diarrhoea at the 6-month follow-up (odds ratio: 2.03 (95% confidence interval: 1.05, 3.92)).

CONCLUSION

The cohort study findings from the REDUCE program have shown that child hand contamination is associated with diarrhoeal disease in rural DRC, and that there is high faecal contamination in child plays spaces and food. These findings provide evidence demonstrating the urgent need to provide clean play spaces for young children and interventions targeting hand hygiene to reduce paediatric exposure to faecal pathogens.

Ingestion of Fecal Bacteria along Multiple Pathways by Young Children in Rural Bangladesh Participating in a Cluster-Randomized Trial of Water, Sanitation, and Hygiene Interventions (WASH Benefits)

Quantifying the contribution of individual exposure pathways to a child's total ingestion of fecal matter could help prioritize interventions to reduce environmental enteropathy and diarrhea. This study used data on fecal contamination of drinking water, food, soil, hands, and objects and second-by-second data on children's contacts with these environmental reservoirs in rural Bangladesh to assess the relative contribution of different pathways to children's ingestion of fecal indicator bacteria and if ingestion decreased with the water, sanitation, and hygiene interventions implemented in the WASH Benefits Trial. Our model estimated that rural Bangladeshi children <36 months old consume 3.6-4.9 log₁₀ most probable number E. coli/day. Among children <6 months, placing objects in the mouth accounted for 60% of E. coli ingested. For children 6-35 months old, mouthing their own hands, direct soil ingestion, and ingestion of contaminated food were the primary pathways of E. coli ingestion. The amount of E. coli ingested by children and the predominant pathways of E. coli ingestion were unchanged by the water, sanitation, and hygiene interventions. These results highlight contaminated soil, children's hands, food, and objects as primary pathways of E. coli ingestion and emphasize the value of intervening along these pathways.

Longitudinal monitoring of SARS-CoV-2 RNA on high-touch surfaces in a community setting

Environmental surveillance of surface contamination is an unexplored tool for understanding transmission of SARS-CoV-2 in community settings. We conducted longitudinal swab sampling of high-touch non-porous surfaces in a Massachusetts town during a COVID-19 outbreak from April to June 2020. Twenty-nine of 348 (8.3 %) surface samples were positive for SARS-CoV-2, including crosswalk buttons, trash can handles, and door handles of essential business entrances (grocery store, liquor store, bank, and gas station). The estimated risk of infection from touching a contaminated surface was low (less than 5 in 10,000), suggesting fomites play a minimal role in SARS-CoV-2 community transmission. The weekly percentage of positive samples (out of n=33 unique surfaces per week) best predicted variation in city-level COVID-19 cases using a 7-day lead time. Environmental surveillance of SARS-CoV-2 RNA on high-touch surfaces could be a useful tool to provide early warning of COVID-19 case trends.

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.

Pathogen flows from on-site sanitation systems in low-income urban neighborhoods, Dhaka: A quantitative environmental assessment

BACKGROUND

Despite wide usage of on-site sanitation, there is limited field-based evidence on the removal or release of pathogens from septic tanks and other primary treatment systems, such as anaerobic baffled reactors (ABR). In two low-income areas in Dhaka, we conducted a cross-sectional study to explore pathogen loads discharged from commonly used on-site sanitation-systems and their transport in nearby drains and waterways.

METHODS

We collected samples of drain water, drain sediment, canal water, and floodwater from April-October 2019. Sludge, supernatant, and effluent samples were also collected from septic tanks and ABRs. We investigated the presence and concentration of selected enteric pathogens (Shigella, Vibrio cholerae (V. cholerae), Salmonella Typhi (S. Typhi), Norovirus Genogroup-II (NoV-GII), and Giardia) and presence of Cryptosporidium in these samples using quantitative polymerase chain reaction (qPCR).The equivalent genome copies (EGC) of individual pathogens were estimated in each sample by interpolation of the mean Ct value to the corresponding standard curve and the dilution factor for each sample type. Absolute quantification was expressed as log₁₀ EGC per 100 mL for the water samples and log₁₀ EGC per gram for the sediment samples.

RESULTS

Among all samples tested (N = 151), 89% were contaminated with Shigella, 68% with V. cholerae and NoV-GII, 32% with Giardia, 17% with S. Typhi and 6% with Cryptosporidium. A wide range of concentration of pathogens [range: mean log₁₀ concentration of Giardia = 0.74 EGC/100 mL in drain ultrafiltration samples to mean log₁₀ concentration of NoV-GII and Giardia = 7.11 EGC/100 mL in ABR sludge] was found in all environmental samples. The highest pathogen concentrations were detected in open drains [range: mean log₁₀ concentration = 2.50-4.94 EGC/100 mL], septic tank effluent [range: mean log₁₀ concentration = 3.32-4.65 EGC/100 mL], and ABR effluent [range: mean log₁₀ concentration = 2.72-5.13 EGC/100 mL].

CONCLUSIONS

High concentrations of pathogens (particularly NoV-GII, V.cholerae and Shigella) were frequently detected in environmental samples from two low-income urban neighbourhoods of Dhaka city. The numerous environmental exposure pathways for children and adults make these findings of public health concern. These results should prompt rethinking of how to achieve safe sanitation solutions that protect public health in dense low-income areas. In particular, improved management and maintenance regimes, further treatment of liquid effluent from primary treatment processes, and appropriate application of onsite, decentralised and offsite sanitation systems given the local context.

Microbial Indicators of Fecal Pollution: Recent Progress and Challenges in Assessing Water Quality

PURPOSE OF REVIEW

Fecal contamination of water is a major public health concern. This review summarizes recent developments and advancements in water quality indicators of fecal contamination.

RECENT FINDINGS

This review highlights a number of trends. First, fecal indicators continue to be a valuable tool to assess water quality and have expanded to include indicators able to detect sources of fecal contamination in water. Second, molecular methods, particularly PCR-based methods, have advanced considerably in their selected targets and rigor, but have added complexity that may prohibit adoption for routine monitoring activities at this time. Third, risk modeling is beginning to better connect indicators and human health risks, with the accuracy of assessments currently tied to the timing and conditions where risk is measured. Research has advanced although challenges remain for the effective use of both traditional and alternative fecal indicators for risk characterization, source attribution and apportionment, and impact evaluation.

Anyen NE, Akumwena A. Making a Case for Infection Control at Public Places of Convenience in Accra, Ghana

In Ghana, environmental hygiene remains a major problem and infection control measures are hardly practised, particularly outside of the hospital. To provide evidence for infection control measures at public places of convenience in Accra (capital city of Ghana), this study was performed. The aim of the study was to evaluate microbial contamination of door handles at public places of convenience in Accra and assess the public health risk. A total of 183 swab specimens were collected aseptically from door handles of public places of convenience of shops, schools, hospitals, lorry stations, churches, and markets. The samples were cultured on bacteriological media, and the isolated organisms were identified. The most prevalent bacterial agent isolated was Bacillus spp. (55.7%), followed by Staphylococcus aureus (20.2%), coagulase-negative staphylococcus spp. (17.1%), Citrobacter freundii (6.0%), Citrobacter koseri (4.4%), and Salmonella Paratyphi A (3.8%). Although in low prevalence, a wide range of enteric bacteria were isolated from door handles, accounting for 12 of the 16 isolated organisms. In conclusion, door handles of places of convenience in Accra harbour several pathogenic microorganisms, especially enteric organisms. This study highlights the need for proper disinfection of door handles of places of convenience in Accra as well as handwashing after visiting such places.

Determinants of Childhood Zoonotic Enteric Infections in a Semirural Community of Quito, Ecuador

Domestic animals in the household environment have the potential to affect a child's carriage of zoonotic enteric pathogens and risk of diarrhea. This study examines the risk factors associated with pediatric diarrhea and carriage of zoonotic enteric pathogens among children living in communities where smallholder livestock production is prevalent. We conducted an observational study of children younger than 5 years that included the analysis of child (n = 306) and animal (n = 480) fecal samples for Campylobacter spp., atypical enteropathogenic Escherichia coli, Shiga toxin-producing E. coli, Salmonella spp., Yersinia spp., Cryptosporidium parvum, and Giardia lamblia. Among these seven pathogens, Giardia was the most commonly identified pathogen among children and animals in the same household, most of which was found in child-dog pairs. Campylobacter spp. was also relatively common within households, particularly among child-chicken and child-guinea pig pairs. We used multivariable Poisson regression models to assess risk factors associated with a child being positive for at least one zoonotic enteric pathogen or having diarrhea during the last week. Children who interacted with domestic animals-a behavior reported by nearly three-quarters of households owning animals-were at an increased risk of colonization with at least one zoonotic enteric pathogen (prevalence ratio [PR] = 1.56, 95% CI: 1.00-2.42). The risk of diarrhea in the last seven days was elevated but not statistically significant (PR = 2.27, CI: 0.91, 5.67). Interventions that aim to reduce pediatric exposures to enteric pathogens will likely need to be incorporated with approaches that remove animal fecal contamination from the domestic environment and encourage behavior change aimed at reducing children's contact with animal feces through diverse exposure pathways.

The WASH Benefits and SHINE trials: interpretation of WASH intervention effects on linear growth and diarrhoea

Child stunting is a global problem and is only modestly responsive to dietary interventions. Numerous observational studies have shown that water quality, sanitation, and handwashing (WASH) in a household are strongly associated with linear growth of children living in the same household. We have completed three randomised efficacy trials testing improved household-level WASH with and without improved infant and young child feeding (IYCF) on stunting and diarrhoea in Bangladesh, Kenya, and Zimbabwe. In all trials, improved IYCF had a statistically significant benefit, but WASH had no effect on linear growth. In observational analyses of data from the control groups of the three trials, baseline sanitation was a strong risk factor for stunting in the study populations, suggesting this frequently reported association might be confounded by unmeasured factors of household wellbeing. WASH interventions reduced diarrhoea in Bangladesh, but not in Kenya or Zimbabwe. Intervention promoters visited participants six times per month in Bangladesh compared with monthly in Kenya and Zimbabwe; a review of the literature shows that virtually all published studies that have reported an effect on diarrhoea through home-based water treatment and handwashing promotion achieved high adherence by visiting participants at daily to fortnightly intervals. Despite achieving substantial behavioural change and significant reduction in infection prevalence for some enteric pathogens, detection of enteropathogens among children in the WASH groups of the trials was typically at ten times higher prevalence compared with high-income countries. Considering these results, we recommend that future research in the WASH sector focus on developing and evaluating interventions that are radically more effective in reducing faecal contamination in the domestic environment than the interventions implemented in these trials.

Human fecal contamination of water, soil, and surfaces in households sharing poor-quality sanitation facilities in Maputo, Mozambique

Identifying the origin of fecal contamination can support more effective interventions to interrupt enteric pathogen transmission. Microbial source tracking (MST) assays may help to identify environmental routes of pathogen transmission although these assays have performed poorly in highly contaminated domestic settings, highlighting the importance of both diagnostic validation and understanding the context-specific ecological, physical, and sociodemographic factors driving the spread of fecal contamination. We assessed fecal contamination of compounds (clusters of 2-10 households that share sanitation facilities) in low-income neighborhoods of urban Maputo, Mozambique, using a set of MST assays that were validated with animal stool and latrine sludge from study compounds. We sampled five environmental compartments involved in fecal microbe transmission and exposure: compound water source, household stored water and food preparation surfaces, and soil from the entrance to the compound latrine and the entrances to each household. Each sample was analyzed by culture for the general fecal indicator Escherichia coli (cEC) and by real-time PCR for the E. coli molecular marker EC23S857, human-associated markers HF183/BacR287 and Mnif, and GFD, an avian-associated marker. We collected 366 samples from 94 households in 58 compounds. At least one microbial target (indicator organism or marker gene) was detected in 96% of samples (353/366), with both E. coli targets present in the majority of samples (78%). Human targets were frequently detected in soils (59%) and occasionally in stored water (17%) but seldom in source water or on food surfaces. The avian target GFD was rarely detected in any sample type but was most common in soils (4%). To identify risk factors of fecal contamination, we estimated associations with sociodemographic, meteorological, and physical sample characteristics for each microbial target and sample type combination using Bayesian censored regression for target concentration responses and Bayesian logistic regression for target detection status. Associations with risk factors were generally weak and often differed in direction between different targets and sample types, though relationships were somewhat more consistent for physical sample characteristics. Wet soils were associated with elevated concentrations of cEC and EC23S857 and odds of detecting HF183. Water storage container characteristics that expose the contents to potential contact with hands and other objects were weakly associated with human target detection. Our results describe a setting impacted by pervasive domestic fecal contamination, including from human sources, that was largely disconnected from the observed variation in socioeconomic and sanitary conditions. This pattern suggests that in such highly contaminated settings, transformational changes to the community environment may be required before meaningful impacts on fecal contamination can be realized.

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.

Poultry Ownership Associated with Increased Risk of Child Diarrhea: Cross-Sectional Evidence from Uganda

Domestic animals have been associated with enteric infections in young children and can also be carriers of respiratory viruses. We conducted a cross-sectional assessment of health outcomes in children aged < 5 years associated with animal presence among 793 rural households in Uganda. We recorded the 2-week prevalence of diarrhea and respiratory infections in children, and the number of cows, poultry, sheep/goats, and pigs in the household. We used generalized linear models with robust standard errors to estimate the prevalence ratio (PR) for diarrhea and respiratory infections associated with households owning the above- versus below-median number of animals. We conducted unadjusted and adjusted analyses controlling for socioeconomic, water, sanitation, and hygiene indicators. Children in households with the above-median number (> 5) of poultry had 83% higher diarrhea prevalence than those with ≤ 5 poultry (adjusted PR = 1.83 [1.04, 3.23], P = 0.04). Children in households with the above-median number (> 2) of cows had 48% lower prevalence of respiratory infection than those with ≤ 2 cows (adjusted PR = 0.52 [0.35, 0.76], P < 0.005). There were no other significant associations between domestic animals and child health. Studies should assess if barring chickens from indoor living quarters and sanitary disposal of chicken and other animal feces can reduce childhood zoonotic infections.

Ruminant Fecal Contamination of Drinking Water Introduced Post-Collection in Rural Kenyan Households

In sub-Saharan Africa, many families travel to collect water and store it in their homes for daily use, presenting an opportunity for the introduction of fecal contamination. One stored and one source water sample were each collected from 45 households in rural Kenya. All 90 samples were analyzed for fecal indicator bacteria (E. coli and enterococci) and species-specific contamination using molecular microbial source tracking assays. Human (HF183), avian (GFD), and ruminant (BacR) contamination were detected in 52, two, and four samples, respectively. Stored water samples had elevated enterococci concentrations (p < 0.01, Wilcoxon matched pairs test) and more frequent BacR detection (89% versus 27%, p < 0.01, McNemar's exact test) relative to source water samples. fsQCA (fuzzy set qualitative comparative analysis) was conducted on the subset of households with no source water BacR contamination to highlight combinations of factors associated with the introduction of BacR contamination to stored water supplies. Three combinations were identified: (i) ruminants in the compound, safe water extraction methods, and long storage time, (ii) ruminants, unsafe water extraction methods, and no soap at the household handwashing station, and (iii) long storage time and no soap. This suggests that multiple pathways contribute to the transmission of ruminant fecal contamination in this context, which would have been missed if data were analyzed using standard regression techniques.

High Genomic Diversity and Heterogenous Origins of Pathogenic and Antibiotic-Resistant Escherichia coli in Household Settings Represent a Challenge to Reducing Transmission in Low-Income Settings

Escherichia coli is present in multiple hosts and environmental compartments as a normal inhabitant, temporary or persistent colonizer, and as a pathogen. Transmission of E. coli between hosts and with the environment is considered to occur more often in areas with poor sanitation. We performed whole-genome comparative analyses on 60 E. coli isolates from soils and fecal sources (cattle, chickens, and humans) in households in rural Bangladesh. Isolates from household soils were in multiple branches of the reconstructed phylogeny, intermixed with isolates from fecal sources. Pairwise differences between all strain pairs were large (minimum, 189 single nucleotide polymorphisms [SNPs]), suggesting high diversity and heterogeneous origins of the isolates. The presence of multiple virulence and antibiotic resistance genes is indicative of the risk that E. coli from soil and feces represent for the transmission of variants that pose potential harm to people. Analysis of the accessory genomes of the Bangladeshi E. coli relative to E. coli genomes available in NCBI identified a common pool of accessory genes shared among E. coli isolates in this geographic area. Together, these findings indicate that in rural Bangladesh, a high level of E. coli in soil is likely driven by contributions from multiple and diverse E. coli sources (human and animal) that share an accessory gene pool relatively unique to previously published E. coli genomes. Thus, interventions to reduce environmental pathogen or antimicrobial resistance transmission should adopt integrated One Health approaches that consider heterogeneous origins and high diversity to improve effectiveness and reduce prevalence and transmission.IMPORTANCEEscherichia coli is reported in high levels in household soil in low-income settings. When E. coli reaches a soil environment, different mechanisms, including survival, clonal expansion, and genetic exchange, have the potential to either maintain or generate E. coli variants with capabilities of causing harm to people. In this study, we used whole-genome sequencing to identify that E. coli isolates collected from rural Bangladeshi household soils, including pathogenic and antibiotic-resistant variants, are diverse and likely originated from multiple diverse sources. In addition, we observed specialization of the accessory genome of this Bangladeshi E. coli compared to E. coli genomes available in current sequence databases. Thus, to address the high level of pathogenic and antibiotic-resistant E. coli transmission in low-income settings, interventions should focus on addressing the heterogeneous origins and high diversity.

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.

Do domestic animals contribute to bacterial contamination of infant transmission pathways? Formative evidence from Ethiopia

Child stunting is associated with poor water, sanitation and hygiene (WASH), partly due to the effect of infection on intestinal nutrient absorption. WASH interventions, however, show little effect on growth. A hypothesis is that bacterial contamination of hands and floors from domestic animals and their faeces, and subsequent ingestion via infant hand-to-mouth behaviours, may explain this. This formative study used microbial testing and survey and observational data from 20 households in Ethiopia to characterise principle bacterial transmission pathways to infants, considering WASH facilities and practices, infant behaviours and animal exposure. Microbial swabbing showed the contamination of hands and floor surfaces from thermotolerant coliform bacteria. Animal husbandry practices, such as keeping animals inside, contributed significantly (all p < 0.005). There was no evidence that latrine facilities mitigated contamination across infant (p = 0.76) or maternal (p = 0.86) hands or floor surfaces (p = 0.36). This small study contributes to the evidence that animal faeces are an important source of domestic bacterial contamination. The results imply that interventions aiming to reduce pathogen transmission to infants should think beyond improving WASH and also consider the need to separate infants and animals in the home. Intervention studies will be required to determine whether this reduces infant infection and improves linear growth.

Interventions to improve disposal of child faeces for preventing diarrhoea and soil-transmitted helminth infection

BACKGROUND

Diarrhoea and soil-transmitted helminth (STH) infections represent a large disease burden worldwide, particularly in low-income countries. As the aetiological agents associated with diarrhoea and STHs are transmitted through faeces, the safe containment and management of human excreta has the potential to reduce exposure and disease. Child faeces may be an important source of exposure even among households with improved sanitation.

OBJECTIVES

To assess the effectiveness of interventions to improve the disposal of child faeces for preventing diarrhoea and STH infections.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, Embase, and 10 other databases. We also searched relevant conference proceedings, contacted researchers, searched websites for organizations, and checked references from identified studies. The date of last search was 27 September 2018.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and non-randomized controlled studies (NRS) that compared interventions aiming to improve the disposal of faeces of children aged below five years in order to decrease direct or indirect human contact with such faeces with no intervention or a different intervention in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used meta-analyses to estimate pooled measures of effect where appropriate, or described the study results narratively. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Sixty-three studies covering more than 222,800 participants met the inclusion criteria. Twenty-two studies were cluster RCTs, four were controlled before-and-after studies (CBA), and 37 were NRS (27 case-control studies (one that included seven study sites), three controlled cohort studies, and seven controlled cross-sectional studies). Most study sites (56/69) were in low- or lower middle-income settings. Among studies using experimental study designs, most interventions included child faeces disposal messages along with other health education messages or other water, sanitation, and hygiene (WASH) hardware and software components. Among observational studies, the main risk factors relevant to this review were safe disposal of faeces in the latrine or defecation of children under five years of age in a latrine.Education and hygiene promotion interventions, including child faeces disposal messages (no hardware provision)Four RCTs found that diarrhoea incidence was lower, reducing the risk by an estimated 30% in children under six years old (rate ratio 0.71, 95% confidence interval (CI) 0.59 to 0.86; 2 trials, low-certainty evidence). Diarrhoea prevalence measured in two other RCTs in children under five years of age was lower, but evidence was low-certainty (risk ratio (RR) 0.93, 95% CI 0.84 to 1.04; low-certainty evidence).Two controlled cohort studies that evaluated such an intervention in Bangladesh did not detect a difference on diarrhoea prevalence (RR 0.91, 95% CI 0.64 to 1.28; very low-certainty evidence). Two controlled cross-sectional studies that evaluated the Health Extension Package in Ethiopia were associated with a lower two-week diarrhoea prevalence in 'model' households than in 'non-model households' (odds ratio (OR) 0.26, 95% CI 0.16 to 0.42; very low-certainty evidence).Programmes to end open defecation by all (termed community-led total sanitation (CLTS) interventions plus adaptations)Four RCTs measured diarrhoea prevalence and did not detect an effect in children under five years of age (RR 0.92, 95% CI 0.79 to 1.07; moderate-certainty evidence). The analysis of two trials did not demonstrate an effect of the interventions on STH infection prevalence in children (pooled RR 1.03, 95% CI 0.64 to 1.65; low-certainty evidence).One controlled cross-sectional study compared the prevalence of STH infection in open defecation-free (ODF) villages that had received a CLTS intervention with control villages and reported a higher level of STH infection in the intervention villages (RR 2.51, 95% CI 1.74 to 3.62; very low-certainty evidence).Sanitation hardware and behaviour change interventions, that included child faeces disposal hardware and messagingTwo RCTs had mixed results, with no overall effect on diarrhoea prevalence demonstrated in the pooled analysis (RR 0.79, 95% CI 0.49 to 1.26; very low-certainty evidence).WASH hardware and education/behaviour change interventionsOne RCT did not demonstrate an effect on diarrhoea prevalence (RR 1.15, 95% CI 0.93 to 1.41; very low-certainty evidence).Two CBAs reported that the intervention reduced diarrhoea incidence by about a quarter in children under five years of age, but evidence was very low-certainty (rate ratio 0.77, 95% CI 0.71 to 0.84). Another CBA reported that the intervention reduced the prevalence of STH in an intervention village compared to a control village, again with GRADE assessed at very low-certainty (OR 0.17, 95% CI 0.02 to 0.73).Case-control studiesPooled results from case-control studies that presented data for child faeces disposal indicated that disposal of faeces in the latrine was associated with lower odds of diarrhoea among all ages (OR 0.73, 95% CI: 0.62 to 0.85; 23 comparisons; very low-certainty evidence). Pooled results from case-control studies that presented data for children defecating in the latrine indicated that children using the latrine was associated with lower odds of diarrhoea in all ages (OR 0.54, 95% CI 0.33 to 0.90; 7 studies; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Evidence suggests that the safe disposal of child faeces may be effective in preventing diarrhoea. However, the evidence is limited and of low certainty. The limited research on STH infections provides only low and very-low certainty evidence around effects, which means there is currently no reliable evidence that interventions to improve safe disposal of child faeces are effective in preventing such STH infections.While child faeces may represent a source of exposure to young children, interventions generally only address it as part of a broader sanitation initiative. There is a need for RCTs and other rigorous studies to assess the effectiveness and sustainability of different hardware and software interventions to improve the safe disposal of faeces of children of different age groups.

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.

Microbial Source Tracking Using 16S rRNA Amplicon Sequencing Identifies Evidence of Widespread Contamination from Young Children's Feces in an Urban Slum of Nairobi, Kenya

Child exposure to fecal contamination remains common in low- and middle-income countries after sanitation interventions. Unsafe disposal of children's feces may contribute to this continued exposure, but its relative importance to domestic fecal contamination is not well understood. To address this gap, we interviewed and collected environmental samples (drinking water, caregiver hands, child hands, surfaces, soil, open drainage ditches, standing water, streams) from 40 households in Kibera, an urban slum in Nairobi, Kenya. To track young children's feces (<3 years old) separately from other human-associated fecal sources, we validated distance-based and Bayesian (SourceTracker) microbial source tracking methods using amplicon-based sequencing of the 16S rRNA gene. Contamination by young children's feces could be identified and distinguished separately from older child/adult feces with high sensitivity and specificity in water and soil. Among environmental samples, young children's feces were almost always identified as the dominant source of human fecal contamination inside households (hands, surfaces) whereas older children/adult feces were often identified as the dominant source outside households (standing water, streams, soil). Markers for young children's feces were also detected in standing water and streams, and markers for both fecal sources were equally likely to be dominant in open ditches. These results establish motivation for sanitation interventions that directly address child feces management.

Risk Factors Associated with Feeding Children under 2 Years in Rural Malawi-A Formative Study

Diarrhoeal disease remains one of the leading causes of morbidity and mortality in the under-five population, particularly in low income settings such as sub-Saharan Africa. Despite significant progress in sanitation and water access, faecal-oral infections persist in these populations. Therefore, a better understanding of these transmission pathways, and how potential risk factors can be reduced within low income contexts is needed. This study, conducted in Southern Malawi from June to October 2017, used a mixed methods approach to collect data from household surveys (n = 323), checklists (n = 31), structured observations (n = 80), and microbiological food samples (n = 20). Results showed that food prepared for immediate consumption (primarily porridge for children) posed a low health risk. Poor hygiene practices increased the risk of contamination from shared family meals. Faecal and nosocomial bacteria were associated with poor hand hygiene and unhygienic eating conditions. Leftover food storage and inadequate pre-consumption heating increased the risk of contamination. Improvements in food hygiene and hand hygiene practices at critical points could reduce the risk of diarrhoeal disease for children under 2 years but must consider the contextual structural barriers to improved practice like access to handwashing facilities, soap, food and water storage.

Effects of water, sanitation, handwashing and nutritional interventions on soil-transmitted helminth infections in young children: A cluster-randomized controlled trial in rural Bangladesh

BACKGROUND

Soil transmitted helminths (STH) infect >1.5 billion people. Mass drug administration (MDA) effectively reduces infection; however, there is evidence for rapid reinfection and risk of potential drug resistance. We conducted a randomized controlled trial in Bangladesh (WASH Benefits, NCT01590095) to assess whether water, sanitation, hygiene and nutrition interventions, alone and combined, reduce STH in a setting with ongoing MDA.

METHODOLOGY/PRINCIPAL FINDINGS

In 2012-2013, we randomized 720 clusters of 5551 pregnant women into water treatment, sanitation, handwashing, combined water+sanitation+handwashing (WSH), nutrition, nutrition+WSH (N+WSH) or control arms. In 2015-2016, we enrolled 7795 children, aged 2-12 years, of 4102 available women for STH follow-up and collected stool from 7187. We enumerated STH infections with Kato-Katz. We estimated intention-to-treat intervention effects on infection prevalence and intensity. Participants and field staff were not blinded; laboratory technicians and data analysts were blinded. Prevalence among controls was 36.8% for A. lumbricoides, 9.2% for hookworm and 7.5% for T. trichiura. Most infections were low-intensity. Compared to controls, the water intervention reduced hookworm by 31% (prevalence ratio [PR] = 0.69 (0.50,0.95), prevalence difference [PD] = -2.83 (-5.16,-0.50)) but did not affect other STH. Sanitation improvements reduced T. trichiura by 29% (PR = 0.71 (0.52,0.98), PD = -2.17 (-4.03,-0.38)), had a similar borderline effect on hookworm and no effect on A. lumbricoides. Handwashing and nutrition interventions did not reduce any STH. WSH and N+WSH reduced hookworm prevalence by 29-33% (WSH: PR = 0.71 (0.52,0.99), PD = -2.63 (-4.95,-0.31); N+WSH: PR = 0.67 (0.50,0.91), PD = -3.00 (-5.14,-0.85)) and marginally reduced A. lumbricoides. Effects on infection intensity were similar.

CONCLUSIONS/SIGNIFICANCE

In a low-intensity infection setting with MDA, we found modest but sustained hookworm reduction from water treatment and combined WSH interventions. Impacts were more pronounced on STH species with short vs. long-term environmental survival. Our findings suggest possible waterborne transmission for hookworm. Water treatment and sanitation improvements can augment MDA to interrupt STH transmission.

TRIAL REGISTRATION

NCT01590095.

Quantification of Microbial Source Tracking and Pathogenic Bacterial Markers in Water and Sediments of Tiaoxi River (Taihu Watershed)

Taihu Lake is one of the largest freshwater lakes in China, serving as an important source of drinking water; >60% of source water to this lake is provided by the Tiaoxi River. This river faces serious fecal contamination issues, and therefore, a comprehensive investigation to identify the sources of fecal contamination was carried out and is presented here. The performance of existing universal (BacUni and GenBac), human (HF183-Taqman, HF183-SYBR, BacHum, and Hum2), swine (Pig-2-Bac), ruminant (BacCow), and avian (AV4143 and GFD) associated microbial source tracking (MST) markers was evaluated prior to their application in this region. The specificity and sensitivity results indicated that BacUni, HF183-TaqMan, Pig-2-Bac, and GFD assays are the most suitable in identifying human and animal fecal contamination. Therefore, these markers along with marker genes specific to selected bacterial pathogens were quantified in water and sediment samples of the Tiaoxi River, collected from 15 locations over three seasons during 2014 and 2015. Total/universal Bacteroidales markers were detected in all water and sediment samples (mean concentration 6.22 log10 gene copies/100 ml and 6.11 log10 gene copies/gram, respectively), however, the detection of host-associated MST markers varied. Human and avian markers were the most frequently detected in water samples (97 and 89%, respectively), whereas in sediment samples, only human-associated markers were detected more often (86%) than swine (64%) and avian (8.8%) markers. The results indicate that several locations in the Tiaoxi River are heavily polluted by fecal contamination and this correlated well with land use patterns. Among the five bacterial pathogens tested, Shigella spp. and Campylobacter jejuni were the most frequently detected pathogens in water (60% and 62%, respectively) and sediment samples (91% and 53%, respectively). Shiga toxin-producing Escherichia coli (STEC) and pathogenic Leptospira spp. were less frequently detected in water samples (55% and 33%, respectively) and sediment samples (51% and 13%, respectively), whereas E. coli O157:H7 was only detected in sediment samples (11%). Overall, the higher prevalence and concentrations of Campylobacter jejuni, Shigella spp., and STEC, along with the MST marker detection at a number of locations in the Tiaoxi River, indicates poor water quality and a significant human health risk associated with this watercourse. GRAPHICAL ABSTRACTTracking fecal contamination and pathogens in watersheds using molecular methods.

Risk Factors for Detection, Survival, and Growth of Antibiotic-Resistant and Pathogenic Escherichia coli in Household Soils in Rural Bangladesh

Soils in household environments in low- and middle-income countries may play an important role in the persistence, proliferation, and transmission of Escherichia coli Our goal was to investigate the risk factors for detection, survival, and growth of E. coli in soils collected from household plots. E. coli was enumerated in soil and fecal samples from humans, chickens, and cattle from 52 households in rural Bangladesh. Associations between E. coli concentrations in soil, household-level risk factors, and soil physicochemical characteristics were investigated. Susceptibility to 16 antibiotics and the presence of intestinal pathotypes were evaluated for 175 E. coli isolates. The growth and survival of E. coli in microcosms using soil collected from the households were also assessed. E. coli was isolated from 44.2% of the soil samples, with an average of 1.95 log10 CFU/g dry soil. Soil moisture and clay content were associated with E. coli concentrations in soil, whereas no household-level risk factor was significantly correlated. Antibiotic resistance and pathogenicity were common among E. coli isolates, with 42.3% resistant to at least one antibiotic, 12.6% multidrug resistant (≥3 classes), and 10% potentially pathogenic. Soil microcosms demonstrate growth and/or survival of E. coli, including an enteropathogenic extended-spectrum beta-lactamase (ESBL)-producing isolate, in some, but not all, of the household soils tested. In rural Bangladesh, defined soil physicochemical characteristics appear more influential for E. coli detection in soils than household-level risk factors. Soils may act as reservoirs in the transmission of antibiotic-resistant and potentially pathogenic E. coli and therefore may impact the effectiveness of water, sanitation, and hygiene interventions.IMPORTANCE Soil may represent a direct source or act as an intermediary for the transmission of antibiotic-resistant and pathogenic Escherichia coli strains, particularly in low-income and rural settings. Thus, determining risk factors associated with detection, growth, and long-term survival of E. coli in soil environments is important for public health. Here, we demonstrate that household soils in rural Bangladesh are reservoirs for antibiotic-resistant and potentially pathogenic E. coli strains and can support E. coli growth and survival, and defined soil physicochemical characteristics are drivers of E. coli survival in this environment. In contrast, we found no evidence that household-level factors, including water, sanitation, and hygiene indicators, were associated with E. coli contamination of household soils.

Do Sanitation Improvements Reduce Fecal Contamination of Water, Hands, Food, Soil, and Flies? Evidence from a Cluster-Randomized Controlled Trial in Rural Bangladesh

Sanitation improvements have had limited effectiveness in reducing the spread of fecal pathogens into the environment. We conducted environmental measurements within a randomized controlled trial in Bangladesh that implemented individual and combined water treatment, sanitation, handwashing (WSH) and nutrition interventions (WASH Benefits, NCT01590095). Following approximately 4 months of intervention, we enrolled households in the trial's control, sanitation and combined WSH arms to assess whether sanitation improvements, alone and coupled with water treatment and handwashing, reduce fecal contamination in the domestic environment. We quantified fecal indicator bacteria in samples of drinking and ambient waters, child hands, food given to young children, courtyard soil and flies. In the WSH arm, Escherichia coli prevalence in stored drinking water was reduced by 62% (prevalence ratio = 0.38 (0.32, 0.44)) and E. coli concentration by 1-log (Δlog10 = -0.88 (-1.01, -0.75)). The interventions did not reduce E. coli along other sampled pathways. Ambient contamination remained high among intervention households. Potential reasons include noncommunity-level sanitation coverage, child open defecation, animal fecal sources, or naturalized E. coli in the environment. Future studies should explore potential threshold effects of different levels of community sanitation coverage on environmental contamination.

Fecal Indicator Bacteria along Multiple Environmental Transmission Pathways (Water, Hands, Food, Soil, Flies) and Subsequent Child Diarrhea in Rural Bangladesh

Enteric pathogens can be transmitted through multiple environmental pathways, yet little is known about the relative contribution of each pathway to diarrhea risk among children. We aimed to identify fecal transmission pathways in the household environment associated with prospectively measured child diarrhea in rural Bangladesh. We measured the presence and levels of Escherichia coli in tube wells, stored drinking water, pond water, child hand rinses, courtyard soil, flies, and food in 1843 households. Gastrointestinal symptoms among children ages 0-60 months were recorded concurrently at the time of environmental sample collection and again a median of 6 days later. Incident diarrhea (3 or more loose stools in a 24-h period) was positively associated with the concentration of E. coli on child hands measured on the first visit (incidence rate ratio [IRR] = 1.23, 95% CI 1.06, 1.43 for a log₁₀ increase), while other pathways were not associated. In cross-sectional analysis, there were no associations between concurrently measured environmental contamination and diarrhea. Our findings suggest higher levels of E. coli on child hands are strongly associated with subsequent diarrheal illness rates among children in rural Bangladesh.

The association between domestic animal presence and ownership and household drinking water contamination among peri-urban communities of Kisumu, Kenya

INTRODUCTION

Household drinking water can be contaminated by diarrheagenic enteropathogens at numerous points between the source and actual consumption. Interventions to prevent this contamination have focused on preventing exposure to human waste through interventions to improve drinking water, sanitation and hygiene (WASH). In many cases though, the infectious agent may be of zoonotic rather than human origin suggesting that unsafely managed animal waste may contribute to the contamination of household drinking water and the associated diarrheal disease burden.

METHODS

A cross-sectional household survey of 800 households was conducted across three informal peri-urban neighborhoods of Kisumu, Kenya, collecting stored drinking water samples, administering a household survey including water, sanitation and hygiene infrastructure and behaviors, and recording domestic animal presence and ownership. We used multivariate logistic regression to assess the association of traditional WASH factors and domestic animal presence and ownership on microbial contamination of household drinking water.

RESULTS

The majority of households sampled had fecally contaminated drinking water (67%), defined by the presence of any colony forming units of the fecal indicator bacteria enterococci. After adjustment for potential confounders, including socio-economic status and water and sanitation access, both household animal ownership (aOR 1.31; CI 1.00-1.73, p = 0.05) and the presence of animal waste in the household compound (aOR 1.38; CI 1.01, 1.89, p = 0.04) were found to be significantly associated with household drinking water contamination. None of the conventional WASH variables were found to be significantly associated with household drinking water contamination in the study population.

CONCLUSIONS

Water, sanitation, and hygiene strategies to reduce diarrheal disease should consider the promotion of safe animal contact alongside more traditional interventions focusing on the management of human waste. Future research on fecal contamination of unsafe household drinking water should utilize host-specific markers to determine whether the source is human or animal to prepare targeted public health messages.

Escherichia coli Contamination across Multiple Environmental Compartments (Soil, Hands, Drinking Water, and Handwashing Water) in Urban Harare: Correlations and Risk Factors

Escherichia coli pathotypes (i.e., enteropathogenic and enterotoxigenic) have been identified among the pathogens most responsible for moderate-to-severe diarrhea in low- and middle-income countries (LMICs). Pathogenic E. coli are transmitted from infected human or animal feces to new susceptible hosts via environmental reservoirs such as hands, water, and soil. Commensal E. coli, which includes nonpathogenic E. coli strains, are widely used as fecal bacteria indicator, with their presence associated with increased likelihood of enteric pathogens and/or diarrheal disease. In this study, we investigated E. coli contamination in environmental reservoirs within households (N = 142) in high-population density communities of Harare, Zimbabwe. We further assessed the interconnectedness of the environmental compartments by investigating associations between, and household-level risk factors for, E. coli contamination. From the data we collected, the source and risk factors for E. coli contamination are not readily apparent. One notable exception is the presence of running tap water on the household plot, which is associated with significantly less E. coli contamination of drinking water, handwashing water, and hands after handwashing. In addition, E. coli levels on hands after washing are significantly associated with handwashing water contamination, hand contamination before washing, and diarrhea incidence. Finally, we observed that animal ownership increases E. coli contamination in soil, and E. coli in soil are correlated with contamination on hands before washing. This study highlights the complexity of E. coli contamination in household environments within LMICs. More, larger, studies are needed to better identify sources and exposure pathways of E. coli-and enteric pathogens generally-to identify effective interventions.