Enteric pathogens in stored drinking water and on caregiver's hands in Tanzanian households with and without reported cases of child diarrhea

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.

Molecular detection of waterborne pathogens in infants' drinking water and their relationship with water quality determinants in eastern Ethiopia: loop-mediated isothermal amplification (LAMP)-based study

Cryptosporidium, Shigella, toxin-producing Escherichia coli, and rotavirus were reported to be the most responsible for severe and fatal diarrhea among infants. This study aimed to investigate the presence of these pathogens in infants' drinking water samples and analyzing using water quality determinants in eastern Ethiopia. A molecular (LAMP)-based cross-sectional study design was employed. A total of 410 and 37 water samples were tested from infant point-of-use at household and corresponding water source, respectively, from June 2020 to May, 2021. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 28.5, 30.0, 26.3, and 32.2%, of water samples tested from infant point-of-use, respectively. About 13.2% of the water samples were positive for all (four) pathogens together. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 27.0, 32.4, 29.7, and 37.8%, of water samples tested from water sources, respectively. Positive significant correlation was observed between infant point-of-consumption and water sources from which it is drawn toward the presence of each targeted pathogen. Unimproved water source showed a strong significant association with the presence of Cryptosporidium, Shigella and toxin-producing E. coli. Therefore, efforts should be made in development of improved water sources, source protection safety and health education to caretakers of infants.

Analysing the interplay of environmental virology, public health, and sanitation: a comprehensive review from a Kenyan perspective

This comprehensive review examines the interplay between environmental virology, public health, and sanitation in the unique context of Kenya. The review sheds light on the specific viral threats faced by the country, including waterborne viruses, zoonotic infections, and emerging viral diseases, and their implications for public health. It explores the prevailing public health challenges in Kenya associated with environmental viromics, such as infectious viral diseases, and the rising burden of other infectious particles. The role of sanitation in mitigating viral infections is highlighted, emphasising the importance of clean water supply, proper waste management, and hygienic practises. The review also presents strategies for strengthening environmental virology research in Kenya, including enhancing laboratory capacities and leveraging technological advancements. Furthermore, the policy implications and recommendations derived from the review emphasise the need for multi-sectoral collaboration, evidence-based decision-making, and long-term investments in infrastructure and behaviour change interventions. Implementing these strategies can enhance the understanding of environmental virology, improve public health outcomes, and ensure sustainable sanitation practises in Kenya, ultimately contributing to the well-being of the population and sustainable development.

Microbial assessment of water, sanitation, and hygiene (WaSH) in temporary and permanent settlements two years after Nepal 2015 earthquake

Disaster-induced displacement often causes people to live in temporary settlements that have limited infrastructure and access to water, sanitation, and hygiene (WaSH). Reducing the risk of diarrheal diseases in such situations requires knowing how housing influences the presence of pathogens in water and the interaction between human settlements and exposure to pathogens. A cross-sectional study was conducted in May 2017 in two communities hard-hit by the Nepal 2015 earthquake: one recovered with newly reconstructed houses, and one recovered with residents still living in sheet metal temporary shelters constructed after the earthquake. We collected 60 water (30 drinking water and 30 cleaning water), 30 hand rinse, and 90 environmental swab samples (30 toilet handles, 30 utensils, and 30 water vessels) from selected households in each location and quantified 22 bacterial pathogens using microfluidic quantitative polymerase chain reaction (mfqPCR). A total of 59 samples were randomly selected for amplicon-based sequencing of the 16S rRNA, and it identified bacterial community profiles between these two settlements and their association with target genes of pathogenic bacteria. Target genes like uidA of Escherichia coli and the mip gene of Legionella pnuemophila showed significantly high frequency in specific sample types in temporary settlements than in permanent settlements. A significantly high concentration was observed in temporary settlements for Enterococcus spp. and S. typhimurium, specifically in swab samples. There was a sharp distinction of microbial community profiles between water and hand rinse samples with environmental swab samples, with a large abundance of potentially pathogenic bacteria in swab samples in both settlements. This observation highlighted that fomite could be an important transmission route for pathogens in rural settings and designing key interventions to target different stages of transmission pathways is essential. Overall findings from this study suggest that the recovered settlement with higher quality housing may be less impacted by fecal contamination than recovering settlements and that interventions should be designed to disrupt multiple transmission pathways to reduce pathogen exposure.

Effects of High Temperature and Heavy Precipitation on Drinking Water Quality and Child Hand Contamination Levels in Rural Kenya

Climate change may impact human health through the influence of weather on environmental transmission of diarrhea. Previous studies have found that high temperatures and heavy precipitation are associated with increased diarrhea prevalence, but the underlying causal mechanisms have not been tested and validated. We linked measurements of Escherichia coli in source water (n = 1673), stored drinking water (n = 9692), and hand rinses from children <2 years old (n = 2634) with publicly available gridded temperature and precipitation data (at ≤0.2 degree spatial resolution and daily temporal resolution) by the GPS coordinates and date of sample collection. Measurements were collected over a 3-year period across a 2500 km² area in rural Kenya. In drinking water sources, high 7-day temperature was associated with a 0.16 increase in log₁₀ E. coli levels (p < 0.001, 95% CI: 0.07, 0.24), while heavy 7-day total precipitation was associated with a 0.29 increase in log₁₀ E. coli levels (p < 0.001, 95% CI: 0.13, 0.44). In household stored drinking water, heavy 7-day precipitation was associated with a 0.079 increase in log₁₀ E. coli levels (p = 0.042, 95% CI: 0.07, 0.24). Heavy precipitation did not increase E. coli levels among respondents who treated their water, suggesting that water treatment can mitigate effects on water quality. On child hands, high 7-day temperature was associated with a 0.39 decrease in log₁₀ E. coli levels (p < 0.001, 95% CI: -0.52, -0.27). Our findings provide insight on how climate change could impact environmental transmission of bacterial pathogens in Kenya. We suggest water treatment is especially important after heavy precipitation (particularly when preceded by dry periods) and high temperatures.

Prevalence and spatiotemporal distribution of rotavirus diarrhea among children younger than five years old in Lagos, Nigeria

Data on spatiotemporal distribution of rotavirus diarrhea are limited in many endemic settings. This study determined the prevalence and seasonal distribution of rotavirus among Nigerian children with diarrhea. Here, a total of 406 fecal samples were collected from patients attending six health facilities in Lagos between January - December 2019. Socio-demographic data of each enrolled child were collected. Rotavirus VP6 antigen was detected by enzyme-linked immunoassay (ELISA) and confirmation by VP7 gene detection by reverse transcription polymerase-chain reaction. The overall rotavirus diarrhea prevalence was 16.3% by ELISA with children above 2 years having 29.2% of this prevalence and higher occurrence in females (59.1%) than males (40.9%) (P < .05). Rotavirus diarrhea diagnosis using RT-PCR showed 100% concordance with ELISA. Cases of rotavirus diarrhea were detected from March to July and from September to November with the highest number of cases detected in May and June (22.7% each), followed by July (21.2%). The prevalence of rotavirus diarrhea remains high in Lagos with an emerging higher disease activity in children above 2. A different rotavirus transmission dynamics compared to previous studies from Nigeria and other African countries was found. VP6 ELISA may reliably be used for continuous rotavirus surveillance in Nigeria.

Growth and growth trajectory among infants in early life: contributions of food insecurity and water insecurity in rural Zimbabwe

Introduction

Stunting or linear growth faltering, measured by length-for-age Z-score (LAZ), remains a significant public health challenge, particularly in rural low-income and middle-income countries. It is a marker of inadequate environments in which infants are born and raised. However, the contributions of household resource insecurities, such as food and water, to growth and growth trajectory are understudied.

Methods

We used the cluster-randomised Sanitation Hygiene and Infant Nutrition Efficacy trial to determine the association of household-level food insecurity (FI) and water insecurity (WI) on LAZ and LAZ trajectory among infants during early life. Dimensions of FI (poor access, household shocks, low availability and quality) and WI (poor access, poor quality, low reliability) were assessed with the multidimensional household food insecurity and the multidimensional household water insecurity measures. Infant length was converted to LAZ based on the 2006 WHO Child Growth Standards. We report the FI and WI fixed effects from multivariable growth curve models with repeated measures of LAZ at 1, 3, 6, 12 and 18 months (M1-M18).

Results

A total of 714 and 710 infants were included in our analyses of LAZ from M1 to M18 and M6 to M18, respectively. Mean LAZ values at each time indicated worsening linear growth. From M1 to M18, low food availability and quality was associated with lower LAZ (β=-0.09; 95% -0.19 to -0.13). From M6 to M18, poor food access was associated with lower LAZ (β=-0.11; 95% -0.20 to -0.03). None of the WI dimensions were associated with LAZ, nor with LAZ trajectory over time.

Conclusion

FI, but not WI, was associated with poor linear growth among rural Zimbabwean infants. Specifically, low food availability and quality and poor food access was associated with lower LAZ. There is no evidence of an effect of FI or WI on LAZ trajectory.

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

Background

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

Methods

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

Results

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

Conclusion

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

Bacteriological quality of drinking water from source and point of use and associated factors among households in Eastern Ethiopia

Background

Biological deterioration of drinking water is the major cause of waterborne disease globally. However, there is a paucity of information on identifying the point where deterioration of the bacteriological quality of drinking water occurs (source or point of use) and associated factors among households in developing countries, especially in Ethiopia.

Method

A community based cross-sectional study design was conducted among 425 households in Eastern Ethiopia. Households with at least one child under-five years of age were included in the study. A total of 448 Water samples (425 from households and 23 from water sources) were collected and analyzed by the membrane filtration method to identify Thermotolerant coliform. Binary logistic regression was performed to assess the association between each independent and dependent variable. Adjusted Odd Ratios along with 95% Confidence intervals were estimated to identify factors associated with the outcome variable.

Result

This study revealed that 21.7%; 95% CI (4.5%, 39.1%) of water sources and 83.3%; 95% CI (79.8%, 87.1%) of households’ drinking water were contaminated by thermotolerant coliform. Drinking water samples from households with poor wealth index [AOR = 9.63; 95%CI (2.92, 31.69)], households with unimproved sanitation facility [AOR = 2.81; 95%CI (1.31, 6.01)], households which shares their house with animal [AOR = 3.73; 95%CI (1.66, 8.37)], households that didn’t practice household water treatment [AOR = 3.42; 95%CI (1.60, 7.31)] and not washing hands before water collection [AOR = 7.04; 95%CI (2.22, 22.30)] were significantly associated with deterioration of bacteriological quality of household drinking water.

Conclusion

This study indicates that the bacteriological quality of drinking water deteriorates from source to point of use. Thus, health education programs on water, sanitation, hygienic practice must be enhanced to improve the quality of drinking water.

COVID-19 and handwashing: Implications for water use in Sub-Saharan Africa

Because the main modes of transmission of the COVID-19 virus are respiration and contact, WHO recommends frequent washing of hands with soap under running water for at least 20 s. This article investigates how the level of concern about COVID-19 affects the likelihood of washing hands frequently in sub-Saharan Africa. We discuss the implication of the findings for water-scarce environment. The study makes use of a unique survey dataset from 12 sub-Saharan African countries collected in April 2020 (first round) and May 2020 (second round) and employs an extended ordered probit model with endogenous covariate. The results show that the level of concern about the spread of the virus increases the likelihood of washing hands with soap under running water for a minimum of 20 s at least five times a day. The increase in the probability of handwashing due to concern about COVID-19, ranges from 3% for Benin to 6.3% for South Africa. The results also show heterogeneous effects across gender- and age-groups, locality and various water sources. However, in Africa, the sustainability of the handwashing protocol could be threatened by the severe water scarcity that exists in the region. To sustain frequent handwashing, sub-Saharan Africa needs an effective strategy for water management and supply.

Seasonal and Age-Associated Pathogen Distribution in Newborn Calves with Diarrhea Admitted to ICU

Calf mortality constitutes a substantial loss for agriculture economy-based countries and is also a significant herd problem in developed countries. However, the occurrence and frequency of responsible gastro-intestinal (GI) pathogens in severe newborn diarrhea is still not well known. We aimed to determine the seasonal and age-associated pathogen distribution of severe diarrhea in newborn calves admitted to the intensive care unit (ICU) of Erciyes University animal hospital over a year. Fecal samples were collected during the ICU admissions, and specimens were subjected to a diarrheal pathogen screening panel that included bovine coronavirus (BCoV), Cryptosporidium spp., ETEC K99+, and bovine rotavirus, using RT-PCR and conventional PCR methods. Further isolation experiments were performed with permissive cell cultures and bacterial enrichment methods to identify the clinical importance of infectious pathogen shedding in the ICU. Among the hospitalized calves aged less than 45 days old, the majority of calves originated from small farms (85.9%). The pathogen that most frequently occurred was Cryptosporidium spp. (61.5%) followed by rotavirus (56.4%). The frequency of animal admission to ICU and GI pathogen identification was higher during the winter season (44.9%) when compared to other seasons. Most calves included in the study were 1-6 days old (44.9%). Lastly, co-infection with rotavirus and Cryptosporidium spp. occurred more frequently than other dual or multi-infection events. This study was the first to define severe diarrhea-causing GI pathogens from ICU admitted newborn calves in Turkey.

The interrelationship between water access, exclusive breastfeeding and diarrhea in children: a cross-sectional assessment across 19 African countries

Background

Access to an improved water supply and practicing exclusive breastfeeding are essential for improving maternal and child health outcomes. However, few studies have been equipped to assess the interdependencies between access to improved water, practicing exclusive breastfeeding, and child health. The primary aim of our study was to assess whether access to an improved water supply and water-fetching were associated with mothers’ practice of exclusive breastfeeding.

Methods

We analyzed data on 247 090 mothers with children 5 months old or less using Multiple Indicator Cluster Surveys from 19 African countries. Multivariable logistic regression was used to estimate the relationship between our exposures and exclusive breastfeeding practice, while meta-analytic methods were used to pool adjusted estimates across 19 countries.

Results

The prevalence of exclusive breastfeeding ranged from 22% in Nigeria to 70% in Malawi. Pooled results showed water-fetching was not associated with exclusive breastfeeding (adjusted prevalence odds ratios (aPOR) = 1.04, 95% confidence interval (CI) = 0.89, 1.21). Access to an improved water source was also not associated with exclusive breastfeeding (aPOR = 1.06, 95% CI = 0.94, 1.21). Across all countries many women were spending a significant amount of time water-fetching each day (mean time varied from 20 minutes in Ghana to 115 minutes in Mauritania). Exclusively breastfed children had 33% lower odds of diarrhea than those who were not exclusively breastfed (aPOR = 0.67, 95% CI = 0.56, 0.78).

Conclusion

Our study is the first to assess the relationship between access to improved water supply, water-fetching and exclusive breastfeeding. We found that access to water supply and time spent by mothers fetching water were not associated with exclusive breastfeeding practice, even though mothers spent significant time fetching water.

The interrelationship between water access, exclusive breastfeeding and diarrhea in children: a cross-sectional assessment across 19 African countries

BACKGROUND

Access to an improved water supply and practicing exclusive breastfeeding are essential for improving maternal and child health outcomes. However, few studies have been equipped to assess the interdependencies between access to improved water, practicing exclusive breastfeeding, and child health. The primary aim of our study was to assess whether access to an improved water supply and water-fetching were associated with mothers' practice of exclusive breastfeeding.

METHODS

We analyzed data on 247 090 mothers with children 5 months old or less using Multiple Indicator Cluster Surveys from 19 African countries. Multivariable logistic regression was used to estimate the relationship between our exposures and exclusive breastfeeding practice, while meta-analytic methods were used to pool adjusted estimates across 19 countries.

RESULTS

The prevalence of exclusive breastfeeding ranged from 22% in Nigeria to 70% in Malawi. Pooled results showed water-fetching was not associated with exclusive breastfeeding (adjusted prevalence odds ratios (aPOR) = 1.04, 95% confidence interval (CI) = 0.89, 1.21). Access to an improved water source was also not associated with exclusive breastfeeding (aPOR = 1.06, 95% CI = 0.94, 1.21). Across all countries many women were spending a significant amount of time water-fetching each day (mean time varied from 20 minutes in Ghana to 115 minutes in Mauritania). Exclusively breastfed children had 33% lower odds of diarrhea than those who were not exclusively breastfed (aPOR = 0.67, 95% CI = 0.56, 0.78).

CONCLUSION

Our study is the first to assess the relationship between access to improved water supply, water-fetching and exclusive breastfeeding. We found that access to water supply and time spent by mothers fetching water were not associated with exclusive breastfeeding practice, even though mothers spent significant time fetching water.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal-oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

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.

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.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

None.

Child defecation and feces management practices in rural Bangladesh: Associations with fecal contamination, observed hand cleanliness and child diarrhea

Child open defecation is common in low-income countries and can lead to fecal exposure in the domestic environment. We assessed associations between child feces management practices vs. measures of contamination and child diarrhea among households with children <5 years in rural Bangladesh. We visited 360 households quarterly and recorded caregiver-reported diarrhea prevalence, and defecation and feces disposal practices for children <5 years. We examined caregiver and child hands for visible dirt and enumerated E. coli in child and caregiver hand rinse and stored drinking water samples. Safe child defecation (in latrine/potty) and safe feces disposal (in latrine) was reported by 21% and 23% of households, respectively. Controlling for potential confounders, households reporting unsafe child defecation had higher E. coli prevalence on child hands (prevalence ratio [PR] = 1.12, 1.04-1.20) and in stored water (PR = 1.12,1.03-1.21). Similarly, households reporting unsafe feces disposal had higher E. coli prevalence on child hands (PR = 1.11, 1.02-1.21) and in stored water (PR = 1.10, 1.03-1.18). Effects on E. coli levels were similar. Children in households with unsafe defecation and feces disposal had higher diarrhea prevalence but the associations were not statistically significant. Our findings suggest that unsafe child feces management may present a source of fecal exposure for young children.

Hygiene and Sanitation Practices and the Risk of Morbidity among Children 6–23 Months of Age in Kumbungu District, Ghana

Background. Poor hygiene and sanitation (WASH) practices are characterised by the manifestation of disease and infections, notably diarrhoea and respiratory tract infections (RTIs) among children. This study aimed to assess the influence of WASH practices on the occurrence of diarrhoea and RTIs among children 6–23 months of age.Methods. An analytical cross-sectional study design was conducted in June 2017. Systematic random sampling technique was used to select 300 mothers/caregivers with children aged 6–23 months from 9 communities in the Kumbungu District. We assessed the WASH practices, socio-demographic characteristics of the households and the occurrence of diarrhoea and RTIs among the children with a semi-structured questionnaire. The Hygiene Improvement Framework observational guide was adapted for household sanitation. Backward binary multiple logistic regression was used to determine the WASH practices that significantly predicted morbidity.Results. About 53% and 55.3% of the children reportedly experienced diarrhoea and RTIs, respectively, two weeks before the survey. Caregiver handwashing with soap after defecation [OR = 0.32 (95% C.I: 0.19, 0.52)] and before feeding [OR = 0.50 (95% C.I: 0.30, 0.84)] as well as washing the child’s hands with or without soap before feeding [OR = 0.21 (95% C.I: 0.04, 1.01)] were associated with lower odds of diarrhoea morbidity. The main determinants of RTI morbidity included caregiver handwashing with or without soap after defecation [OR = 0.29 (95% C.I: 0.10, 0.81)] and washing of the child’s hands with soap before feeding [OR = 0.60 (95% C.I: 0.37, 0.99)] However, we found no association between household sanitation and diarrhoea as well as RTI among the children.Conclusion. About a half each of the children had diarrhoea and RTI 2 weeks before the survey. The results emphasise the need for urgent targeting of handwashing and waste disposal programmes to avert the high burden of diarrhoea and RTIs among children.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Epidemiology and genetic screening of diarrheagenic Escherichia coli among symptomatic and asymptomatic children

PURPOSE

Enteropathogens are frequently associated with diarrheal disease. Knowledge of their etiology and epidemiology is essential for the prevention and control of the sickness. This study describes the microbiological and epidemiological features of diarrheal disease in 197 symptomatic and 223 asymptomatic under-five-year-old children from southeastern Brazil, between January 2015 and September 2016.

METHODS

Isolation of Escherichia coli, Salmonella, Shigella and Campylobacter was realized by culture. E. coli strains were screened by multiplex PCR, PFGE and O:H serotyping. Antimicrobial susceptibility testing was also performed.

RESULTS

Most of the 127 enteropathogens isolated were diarrheagenic E. coli (96.1 %), with predominance of several serotypes of enteropathogenic E. coli (EPEC) and enteroaggregative E. coli (EAEC). Age, sex, rotavirus vaccination, recent use of antibiotics and previous contact with pets, were factors that revealed no significant effects on the probability of infection by the predominant pathogens. Even so, higher incomes could be related to a lesser chance of testing positive for EPEC. Evidence of possible EAEC clonal spread was detected, as well as genetic similarity among strains from both symptomatic and asymptomatic children. Resistance to antimicrobial agents was more pronounced among EAEC than EPEC.

CONCLUSION

The occurrence of genetically similar diarrheagenic E. coli in both groups of children, likewise resistant to these agents, underscores the importance of establishing strategies for the prevention of outbreaks, especially among low-income households.

Safely Managed Hygiene: A Risk-Based Assessment of Handwashing Water Quality

Sustainable Development Goal (SDG) Indicator 6.2.1 requires household handwashing facilities to have soap and water, but there are no guidelines for handwashing water quality. In contrast, drinking water quality guidelines are defined: water must be "free from contamination" to be defined as "safely managed" (SDG Indicator 6.1.1). We modeled the hypothesized mechanism of infection due to contaminated handwashing water to inform risk-based guidelines for microbial quality of handwashing water. We defined two scenarios that should not occur: (1) if handwashing caused fecal contamination, indicated using Escherichia coli, on a person's hands to increase rather than decrease and (2) if hand-to-mouth contacts following handwashing caused an infection risk greater than an acceptable threshold. We found water containing <1000 E. coli colony-forming units (CFU) per 100 mL removes E. coli from hands with>99.9% probability. However, for the annual probability of infection to be <1:1000, handwashing water must contain <2 × 10^-6 focus-forming units of rotavirus, <1 × 10^-4 CFU of Vibrio cholerae, and <9 × 10^-6 Cryptosporidium oocysts per 100 mL. Our model suggests that handwashing with nonpotable water will generally reduce fecal contamination on hands but may be unable to lower the annual probability of infection risks from hand-to-mouth contacts below 1:1000.

Risk factors for acute childhood diarrhea: A cross-sectional study comparing refugee camps and host communities in Gambella Region, Ethiopia

BACKGROUND

Diarrhea is one of the most common causes of child morbidity and mortality in refugee camps, aggravated by inadequate water, sanitation and hygiene services, and malnutrition, particularly in developing countries.

METHODOLOGY

A comparative cross-sectional study was conducted to assess acute diarrhea and associated risk factors among under-five children in refugee and host communities in Gambella Region, Ethiopia. Descriptive statistics were used, and bivariate and multivariate logistic regressions were performed to identify variables associated with diarrhea.

RESULTS

A total of 1667 under-five children was included in this study, and prevalence of diarrhea differed between the refugee (38%) and host (33%) communities [OR = 1.37, 95% CI 1.04, 1.8]. Refugee camp households using uncovered water containers, consuming low quantities of water, and lacking hand washing setups were more likely to report children with diarrhea. Within host communities, households were more likely to report acute childhood diarrhea if they consumed surface water or did not have a latrine.

CONCLUSION

The two-week prevalence of diarrhea was significantly higher among children in the refugee camps than those in the host communities. Therefore, further collaboration between government and non-government organizations is required to identify persisting factors of diarrhea transmission in various communities in the region.

Field application of the Micro Biological Survey method for the assessment of the microbiological safety of different water sources in Tanzania

Access to safe water is stated within human rights as essential for life, as water can be a source of severe enteric infections threatening human health, in particular children from Developing Countries. Along with reference methods, need is pressing for alternative methods to flank reference ones to improve water safety on-site monitoring and in the absence of scientific facilities or even electricity supply. The Micro Biological Survey (MBS) method has already been successfully applied to water safety assessment in Developing Countries. A total of 18 water samples were collected from different sources (rivers, dug wells, tap water) within the Rukwa Region, Tanzania, and underwent analysis for Total Coliforms following the MBS method. Globally, rivers showed more frequently contamination, followed by dug wells, tap water and tanks. Results demonstrate the need for continuous monitoring of water sources, even in difficult frameworks lacking electric supply, to help improve control over water quality, possibly using alternative methods to simplify existing protocols.

Where Children Play: Young Child Exposure to Environmental Hazards during Play in Public Areas in a Transitioning Internally Displaced Persons Community in Haiti

Globally, gastrointestinal (GI) infections by enteric pathogens are the second-leading cause of morbidity and mortality in children under five years of age (≤5 years). While GI pathogen exposure in households has been rigorously examined, there is little data about young children's exposure in public domains. Moreover, public areas in low-income settings are often used for other waste disposal practices in addition to human feces, such as trash dumping in areas near households. If young children play in public domains, they might be exposed to interrelated and highly concentrated microbial, chemical, and physical hazards. This study performed structured observations at 36 public areas in an internally displaced persons community that has transitioned into a formal settlement in Haiti. We documented how often young children played in public areas and quantified behaviors that might lead to illness and injury. Children ≤5 years played at all public sites, which included infants who played at 47% of sites. Children touched and mouthed plastic, metal and glass trash, food and other objects from the ground, ate soil (geophagia) and drank surface water. They also touched latrines, animals, animal feces and open drainage canals. Hand-to-mouth contact was one of the most common behaviors observed and the rate of contact significantly differed among developmental stages (infants: 18/h, toddlers: 11/h and young children: 9/h), providing evidence that children could ingest trace amounts of animal/human feces on hands that may contain GI pathogens. These findings demonstrate that water, sanitation and hygiene interventions could be more effective if they consider exposure risks to feces in public domains. Furthermore, this research highlights the need for waste-related interventions to address the broader set of civil conditions that create unsafe, toxic and contaminated public environments where young children play.

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.

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.

Oral Contact Events and Caregiver Hand Hygiene: Implications for Fecal-Oral Exposure to Enteric Pathogens among Infants 3-9 Months Living in Informal, Peri-Urban Communities in Kisumu, Kenya

Childhood diarrhea is one of the leading causes of morbidity and mortality in children under five in low and middle-income countries, second only to respiratory illness. The mouthing behavior that is common in children exposes them to fecal-orally transmitted pathogens that can result in diarrhea; however, there is a need for further evidence on specific exposure routes. This study describes the frequency and diversity of two important routes of enteric pathogen exposure among infants 3-9 months of age: infant oral contact behavior and caregiver handwashing behavior. Data were collected through structured observations of 25 index infants for the oral contact data and 25 households for the caregiver handwashing data in a peri-urban setting in Kisumu (Obunga), Kenya. Breast was the most common type of oral contact event with an average of 3.00 per observation period and 0.5 events per hour. This was followed by a range of physical objects with an average of 2.49 per observation and 0.4 events per hour. The "infant's own hands" was the third most common oral contact, with an average of 2.16 events per hour, and 0.4 oral contact events per hour. Food and liquids were the 4th and 5th most common oral contact events with an average of 1.64 food contacts and 0.52 liquid oral contact events per observation period. Feeding events, including breastfeeding, were the most commonly observed key juncture-71% of total junctures observed were caregivers feeding children. This was followed by child cleaning (23%), caregiver toilet uses at (4%), and lastly food preparation at 2%. HWWS was observed only once before a feeding event (1%), twice after cleaning a child (9%), and twice after caregiver toilet use (40%). The combined implication of data from observing oral contact behavior in children and hand hygiene of caregivers suggests that caregiver hand hygiene prior to feeding events and after cleaning a child are priority interventions.

Fecal Contamination on Produce from Wholesale and Retail Food Markets in Dhaka, Bangladesh

Fresh produce items can become contaminated with enteric pathogens along the supply chain at the preharvest (e.g., irrigation water, soil, fertilizer) or postharvest (e.g., vendor handling or consumer handling) stages. This study assesses the concentrations of fecal indicator bacteria Escherichia coli, enterococci (ENT), and Bacteriodales on surfaces of carrots, eggplants, red amaranth leaves, and tomatoes obtained from both a wholesale market (recently harvested) and neighborhood retail markets in Dhaka, Bangladesh. We detected E. coli in 100% of carrot and red amaranth rinses, 92% of eggplant rinses, and 46% of tomato rinses. Using a molecular microbial source tracking assay, we found that 32% of produce samples were positive for ruminant fecal contamination. Fecal indicator bacteria were more likely to be detected on produce collected in retail markets compared with that in the wholesale market; retail market produce were 1.25 times more likely to have E. coli detected (P = 0.03) and 1.24 times more likely to have ENT detected (P = 0.03) as compared with wholesale market produce. Bacteriodales was detected in higher concentrations in retail market produce samples compared with wholesale market produce samples (0.40 log10 gene copies per 100 cm2 higher, P = 0.03). Our results suggest that ruminant and general fecal contamination of produce in markets in Dhaka is common, and suggest that unsanitary conditions in markets are an important source of produce fecal contamination postharvest.

Following the Worms: Detection of Soil-Transmitted Helminth Eggs on Mothers' Hands and Household Produce in Rural Kenya

Approximately one-quarter of the world’s population is infected with at least one species of soil-transmitted helminth (STH). The role of produce and hands in STH transmission is not well understood. We collected and processed mother hand rinse and garden-grown produce rinse samples from 116 rural households in Kakamega, Kenya, in an area previously identified to have high STH egg contamination in household soil. Ascaris was the only STH species detected; 0.9% of hand rinse, 3.5% of leafy produce, and 1.8% of root produce samples had Ascaris eggs. Our results indicate produce and hands can carry Ascaris eggs. However, due to the low detected prevalence of eggs on hands and produce, and a high prevalence of cooking the produce items tested, these pathways might have a minor contribution to STH exposure in this setting.

Animal Feces Contribute to Domestic Fecal Contamination: Evidence from E. coli Measured in Water, Hands, Food, Flies, and Soil in Bangladesh

Fecal-oral pathogens are transmitted through complex, environmentally mediated pathways. Sanitation interventions that isolate human feces from the environment may reduce transmission but have shown limited impact on environmental contamination. We conducted a study in rural Bangladesh to (1) quantify domestic fecal contamination in settings with high on-site sanitation coverage; (2) determine how domestic animals affect fecal contamination; and (3) assess how each environmental pathway affects others. We collected water, hand rinse, food, soil, and fly samples from 608 households. We analyzed samples with IDEXX Quantitray for the most probable number (MPN) of E. coli. We detected E. coli in source water (25%), stored water (77%), child hands (43%), food (58%), flies (50%), ponds (97%), and soil (95%). Soil had >120 000 mean MPN E. coli per gram. In compounds with vs without animals, E. coli was higher by 0.54 log10 in soil, 0.40 log10 in stored water and 0.61 log10 in food (p < 0.05). E. coli in stored water and food increased with increasing E. coli in soil, ponds, source water and hands. We provide empirical evidence of fecal transmission in the domestic environment despite on-site sanitation. Animal feces contribute to fecal contamination, and fecal indicator bacteria do not strictly indicate human fecal contamination when animals are present.

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

Objective

This study examined associations between household sanitation and enteric infection – including diarrhoeal‐specific outcomes – in children 0–2 years of age in a low‐income, dense urban neighbourhood.

Methods

As part of the MAL‐ED study, 230 children in a low‐income, urban, Indian neighbourhood provided stool specimens at 14–17 scheduled time points and during diarrhoeal episodes in the first 2 years of life that were analysed for bacterial, parasitic (protozoa and helminths) and viral pathogens. From interviews with caregivers in 100 households, the relationship between the presence (and discharge) of household sanitation facilities and any, pathogen‐specific, and diarrhoea‐specific enteric infection was tested through mixed‐effects Poisson regression models.

Results

Few study households (33%) reported having toilets, most of which (82%) discharged into open drains. Controlling for season and household socio‐economic status, the presence of a household toilet was associated with lower risks of enteric infection (RR: 0.91, 95% CI: 0.79–1.06), bacterial infection (RR: 0.87, 95% CI: 0.75–1.02) and protozoal infection (RR: 0.64, 95% CI: 0.39–1.04), although not statistically significant, but had no association with diarrhoea (RR: 1.00, 95% CI: 0.68–1.45) or viral infections (RR: 1.12, 95% CI: 0.79–1.60). Models also suggested that the relationship between household toilets discharging to drains and enteric infection risk may vary by season.

Conclusions

The presence of a household toilet was associated with lower risk of bacterial and protozoal enteric infections, but not diarrhoea or viral infections, suggesting the health effects of sanitation may be more accurately estimated using outcome measures that account for aetiologic agents.

Impact of contaminated household environment on stunting in children aged 12-59 months in Burkina Faso

BACKGROUND

Stunting affects 165 million children worldwide, with repercussions on their survival and development. A contaminated environment is likely to contribute to stunting: frequent faecal-oral transmission possibly causes environmental enteropathy, a chronic inflammatory disorder that may contribute to faltering growth in children. This study's objective was to assess the effect of contaminated environment on stunting in Burkina Faso, where stunting prevalence is persistently high.

METHODS

Panel study of children aged 1-5 years in Kaya. Household socioeconomic characteristics, food needs and sanitary conditions were measured once, and child growth every year (2011-2014). Using multiple correspondence analysis and 12 questions and observations on water, sanitation, hygiene behaviours, yard cleanliness and animal proximity, we constructed a 'contaminated environment' index as a proxy of faecal-oral transmission exposure. Analysis was performed using a generalised structural equation model (SEM), adjusting for repeat observations and hierarchical data.

RESULTS

Stunting (<2 SD height-for-age) prevalence was 29% among 3121 children (median (IQR) age 36 (25-48) months). Environment contamination was widespread, particularly in rural and peri-urban areas, and was associated with stunting (prevalence ratio 1.30; p=0.008), controlling for sex, age, survey year, setting, mother's education, father's occupation, household food security and wealth. This association was significant for children of all ages (1-5 years) and settings. Lower contamination and higher food security had effects of comparable magnitude.

CONCLUSIONS

Environment contamination can be at least as influential as nutritional components in the pathway to stunting. There is a rationale for including interventions to reduce environment contamination in stunting prevention programmes.

Faecal contamination of household drinking water in Rwanda: A national cross-sectional study

Unsafe drinking water is a leading cause of morbidity and mortality, especially among young children in low-income settings. We conducted a national survey in Rwanda to determine the level of faecal contamination of household drinking water and risk factors associated therewith. Drinking water samples were collected from a nationally representative sample of 870 households and assessed for thermotolerant coliforms (TTC), a World Health Organization (WHO)-approved indicator of faecal contamination. Potential household and community-level determinants of household drinking water quality derived from household surveys, the 2012 Rwanda Population and Housing Census, and a precipitation dataset were assessed using multivariate logistic regression. Widespread faecal contamination was present, and only 24.9% (95% CI 20.9-29.4%, n=217) of household samples met WHO Guidelines of having no detectable TTC contamination, while 42.5% (95% CI 38.0-47.1%, n=361) of samples had >100TTC/100mL and considered high risk. Sub-national differences were observed, with poorer water quality in rural areas and Eastern province. In multivariate analyses, there was evidence for an association between detectable contamination and increased open waste disposal in a sector, lower elevation, and water sources other than piped to household or rainwater/bottled. Risk factors for intermediate/high risk contamination (>10TTC/100mL) included low population density, increased open waste disposal, lower elevation, water sources other than piped to household or rainwater/bottled, and occurrence of an extreme rain event the previous day. Modelling suggests non-household-based risk factors are determinants of water quality in this setting, and these results suggest a substantial proportion of Rwanda's population are exposed to faecal contamination through drinking water.

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

We evaluated whether provision and promotion of improved sanitation hardware (toilets and child feces management tools) reduced rotavirus and human fecal contamination of drinking water, child hands, and soil among rural Bangladeshi compounds enrolled in a cluster-randomized trial. We also measured host-associated genetic markers of ruminant and avian feces. We found evidence of widespread ruminant and avian fecal contamination in the compound environment; non-human fecal marker occurrence scaled with animal ownership. Strategies for controlling non- human fecal waste should be considered when designing interventions to reduce exposure to fecal contamination in low-income settings. Detection of a human- associated fecal marker and rotavirus was rare and unchanged by provision and promotion of improved sanitation to intervention compounds. The sanitation intervention reduced ruminant fecal contamination in drinking water and general (non-host specific) fecal contamination in soil but overall had limited effects on reducing fecal contamination in the household environment.

Assessing the impact of sanitation on indicators of fecal exposure along principal transmission pathways: A systematic review

OBJECTIVE

Fecal-oral transmission of enteric and other pathogens due to poor sanitation is a major cause of morbidity and mortality, especially in low- or middle-income settings. Few studies have investigated the impact of sanitation on indicators of transmission, a prerequisite to achieving health gains. This review attempts to summarize the literature to date.

METHODS

We searched leading databases to identify studies that address the effect of sanitation on various transmission pathways including fecal pathogens or indicator bacteria in drinking water, hand contamination, sentinel toys, food, household and latrine surfaces and soil, as well as flies and observations of human feces. This also included studies that assessed the impact of fecal contamination of water supplies based on distance from sanitation facilities. We identified 29 studies that met the review's eligibility criteria.

RESULTS AND CONCLUSION

Overall, the studies found little to no effect from sanitation interventions on these transmission pathways. There was no evidence of effects on water quality (source or household), hand or sentinel toy contamination, food contamination, or contamination of surfaces or soil. There is some evidence that sanitation was associated with reductions in flies and a small effect on observations of feces (Risk Difference -0.03, 95%CI -0.06 to 0.01). Studies show an inverse relationship between the distance of a water supply from a latrine and level of fecal contamination of such water supply. Future evaluations of sanitation interventions should include assessments of effects along transmission pathways in order to better understand the circumstances under which interventions may be effective at preventing disease.

Longitudinal Comparison of Antibiotic Resistance in Diarrheagenic and Non-pathogenic Escherichia coli from Young Tanzanian Children

Enteroaggregative, enteropathogenic, and enterotoxigenic Escherichia coli contribute significantly to the burden of diarrheal infections particularly in developing countries. Antibiotic resistance is increasingly common among bacterial pathogens including pathogenic E. coli. We assessed the relationship between pathogenic E. coli carriage and resistance to six antibiotics in E. coli isolated from young children in rural Tanzania. We surveyed temporal stability in antibiotic resistance in 2492 E. coli isolated from fecal samples obtained from young children in rural Tanzania collected over a 6 months period. Approximately half of the 377 children sampled were exposed to an azithromycin mass treatment program for trachoma control and half resided in control villages. Children were sampled at baseline, 1-, 3-, and 6 months following azithromycin treatment. We compared resistance to six antibiotics in pathogenic and non-pathogenic strains at the population level, within fecal specimens, and within individuals over time using chi-square tests, paired odds ratios, and logistic regression, respectively. Resistance to ampicillin and trimethoprim/sulfamethoxazole was highly prevalent (>65%). Resistance to 5 of 6 antibiotics tested and multi-drug resistance occurred more frequently in pathogenic isolates (p ≤ 0.001) within fecal specimens and overall. Azithromycin mass treatment exposure was significantly associated with increased odds of carriage of isolates resistant to erythromycin (OR 3.64, p < 0.001) and trimethoprim/sulfamethoxazole (OR 1.60, p < 0.05). Pathogenic isolates were approximately twice as likely to be resistant to erythromycin, ampicillin, or trimethoprim/sulfamethoxazole compared to non-pathogenic isolates from the same fecal specimen. The potential linkage between resistance and virulence in E. coli suggests hygiene and sanitation interventions aimed at reducing disease burden could play a role in controlling transmission of antibiotic resistance.

The Determinants of Reported Personal and Household Hygiene Behaviour: A Multi-Country Study

A substantial proportion of the total infectious disease burden world-wide is due to person-to-person spread of pathogens within households. A questionnaire-based survey on the determinants of hand-washing with soap and cleaning of household surfaces was conducted in at least 1000 households in each of twelve countries across the world (N = 12,239). A structural equation model of hygiene behaviour and its consequences derived from theory was then estimated on this dataset for both behaviours, using a maximum likelihood procedure. The analysis showed that the frequency of handwashing with soap is significantly related to how automatically it is performed, and whether or not someone is busy, or tired. Surface cleaning was strongly linked to possessing a cleaning routine, the perception that one is living in a dirty environment and that others are doing the behaviour, whether one has a strong sense of contamination, as well as a felt need to keep one's surroundings tidy. Being concerned with good manners is also linked to the performance of both behaviours. This study is the first to identify the role of manners, orderliness and routine on hygiene behaviours globally. Such findings should prove helpful in designing programs to improve domestic hygiene practices.

Environmental transmission of diarrheal pathogens in low and middle income countries

Every year, more than half a million children die due to diarrheal diseases. Recent studies have identified the most important etiologies of diarrheal disease are enterotoxigenic and enteropathogenic E. coli, Shigella spp., rotavirus, norovirus and Cryptosporidium spp. These etiologies are unsurprisingly characterized by a combination of high shedding, high infectivity, and transmissibility through multiple environmental reservoirs. The relative importance of the transmission routes is likely site-specific. So the impact of interventions, which typically target only one or two environmental reservoirs, is likely also site-specific. The factors influencing the transmission routes most important for diarrheal disease are complex, including - at a minimum - etiology of endemic disease; and water, sanitation, and hygiene infrastructure and practices. The site-specific nature - and complexity of transmission - helps explain the observed variation in impacts of water, sanitation, and hygiene interventions. It may also render efforts to estimate or quantify global means for interventions' impacts irrelevant. The theme of this Perspective is that greater reductions in diarrheal disease transmission in LMICs can be achieved by designing interventions to interrupt the most important environmental transmission pathways. Intervention choice should be informed by site-specific conditions, most notably: diarrheal etiology and existing water, sanitation, and hygiene infrastructure and practices. The theme is discussed through the lens of the characteristics of the most important diarrheal diseases (shedding, infectivity, growth, and persistence) and the general characteristics of environmental reservoirs (exposure pathways and fecal contamination). The discussion highlights when interventions - and combinations of interventions - will be most effective at reducing diarrheal disease burden.

Microbiological effectiveness of household water treatment technologies under field use conditions in rural Tanzania

OBJECTIVES

To assess the microbiological effectiveness of several household water treatment and safe storage (HWTS) options in situ in Tanzania, before consideration for national scale-up of HWTS.

METHODS

Participating households received supplies and instructions for practicing six HWTS methods on a rotating 5-week basis. We analysed 1202 paired samples (source and treated) of drinking water from 390 households, across all technologies. Samples were analysed for thermotolerant (TTC) coliforms, an indicator of faecal contamination, to measure effectiveness of treatment in situ.

RESULTS

All HWTS methods improved microbial water quality, with reductions in TTC of 99.3% for boiling, 99.4% for Waterguard^™ brand sodium hypochlorite solution, 99.5% for a ceramic pot filter, 99.5% for Aquatab^® sodium dichloroisocyanurate (NaDCC) tablets, 99.6% for P&G Purifier of Water^™ flocculent/disinfectant sachets, and 99.7% for a ceramic siphon filter. Microbiological performance was relatively high compared with other field studies and differences in microbial reductions between technologies were not statistically significant.

CONCLUSIONS

Given that microbiological performance across technologies was comparable, decisions regarding scale-up should be based on other factors, including uptake in the target population and correct, consistent, and sustained use over time.

Quantification of Human Norovirus GII on Hands of Mothers with Children Under the Age of Five Years in Bagamoyo, Tanzania

Human noroviruses are the most common cause of viral gastroenteritis worldwide and one of the leading causes of viral diarrhea in children under the age of 5 years. Hands have been shown to play an important role in norovirus transmission. Norovirus outbreaks tend to exhibit strong seasonality, most often occurring during cold, dry months, but recently have also been documented during hot, dry winter months in the southern hemisphere. Other research suggests that rainfall is an important factor in norovirus outbreaks. This study examines the prevalence and concentration of human norovirus GII on the hands of mothers in Bagamoyo, Tanzania, during the rainy and dry seasons. Norovirus GII was detected in approximately 5% of hand rinse samples during both the rainy and dry seasons. Fecal indicator bacteria levels, Escherichia coli and enterococci, in hand rinse samples were not associated with norovirus hand contamination. Turbidity of the hand rinses was found to be associated with norovirus presence on mothers' hands; however, this relationship was only observed during the rainy season. The results suggest mothers' hands serve as a source of norovirus exposure for young children in Tanzanian households, and further work is needed to determine better indicators of norovirus contamination in these environments.

Human and Animal Fecal Contamination of Community Water Sources, Stored Drinking Water and Hands in Rural India Measured with Validated Microbial Source Tracking Assays

We examined pathways of exposure to fecal contamination of human and animal origin in 24 villages in Odisha, India. In a cross-sectional study during the monsoon season, fecal exposure via community water sources (N = 123) and in the home (N = 137) was assessed using human- and nonhuman-associated Bacteroidales microbial source tracking (MST) markers and fecal coliforms (FCs). Detection rates and marker concentrations were examined to pinpoint pathways of human fecal exposure in the public and domestic domains of disease transmission in study communities. Human fecal markers were detected much more frequently in the domestic domain (45% of households) than in public domain sources (8% of ponds; 4% of groundwater drinking sources). Animal fecal markers were widely detected in both domains (74% of ponds, 96% of households, 10% of groundwater drinking sources), indicating ubiquitous risks of exposure to animal feces and zoonotic pathogens. This study confirms an often suggested contamination link from hands to stored water in the home in developing countries separately for mothers' and children's hands and both human and animal fecal contamination. In contrast to MST markers, FCs provided a poor metric to assess risks of exposure to fecal contamination of human origin in this rural setting.

Shared Sanitation Versus Individual Household Latrines in Urban Slums: A Cross-Sectional Study in Orissa, India

A large and growing proportion of the global population rely on shared sanitation facilities despite evidence of a potential increased risk of adverse health outcomes compared with individual household latrines (IHLs). We sought to explore differences between households relying on shared sanitation versus IHLs in terms of demographics, sanitation facilities, and fecal exposure. We surveyed 570 households from 30 slums in Orissa, India, to obtain data on demographics, water, sanitation, and hygiene. Latrine spot-checks were conducted to collect data on indicators of use, privacy, and cleanliness. We collected samples of drinking water and hand rinses to assess fecal contamination. Households relying on shared sanitation were poorer and less educated than those accessing IHLs. Individuals in sharing households were more likely to practice open defecation. Shared facilities were less likely to be functional, less clean, and more likely to have feces and flies. No differences in fecal contamination of drinking water or hand-rinse samples were found. Important differences exist among households accessing shared facilities versus IHLs that may partly explain the apparent adverse health outcomes associated with shared sanitation. As these factors may capture differences in risk and promote sanitary improvements, they should be considered in future policy.

Distribution and risk factors for Plasmodium and helminth co-infections: a cross-sectional survey among children in Bagamoyo district, coastal region of Tanzania

BACKGROUND

Plasmodium and soil transmitted helminth infections (STH) are a major public health problem, particularly among children. There are conflicting findings on potential association between these two parasites. This study investigated the Plasmodium and helminth co-infections among children aged 2 months to 9 years living in Bagamoyo district, coastal region of Tanzania.

METHODS

A community-based cross-sectional survey was conducted among 1033 children. Stool, urine and blood samples were examined using a broad set of quality controlled diagnostic methods for common STH (Ascaris lumbricoides, hookworm, Strongyloides stercoralis, Enterobius vermicularis, Trichuris trichura), schistosoma species and Wuchereria bancrofti. Blood slides and malaria rapid diagnostic tests (mRDTs) were utilized for Plasmodium diagnosis.

RESULTS

Out of 992 children analyzed, the prevalence of Plasmodium infection was 13% (130/992), helminth 28.5% (283/992); 5% (50/992) had co-infection with Plasmodium and helminth. The prevalence rate of Plasmodium, specific STH and co-infections increased significantly with age (p < 0.001), with older children mostly affected except for S. stercoralis monoinfection and co-infections. Spatial variations of co-infection prevalence were observed between and within villages. There was a trend for STH infections to be associated with Plasmodium infection [OR adjusted for age group 1.4, 95% CI (1.0-2.1)], which was more marked for S. stercoralis (OR = 2.2, 95% CI (1.1-4.3). Age and not schooling were risk factors for Plasmodium and STH co-infection.

CONCLUSION

The findings suggest that STH and Plasmodium infections tend to occur in the same children, with increasing prevalence of co-infection with age. This calls for an integrated approach such as using mass chemotherapy with dual effect (e.g., ivermectin) coupled with improved housing, sanitation and hygiene for the control of both parasitic infections.

Laboratory development and field testing of sentinel toys to assess environmental faecal exposure of young children in rural India

BACKGROUND

Sentinel toys are increasingly used as a method of assessing young children's exposure to faecal pathogens in households in low-income settings. However, there is no consensus on the suitability of different approaches.

METHODS

We evaluated three types of toy balls with different surfaces (plastic, rubber, urethane) in the laboratory to compare the uptake of faecal indicator bacteria (Escherichia coli) on their surface. We performed bacteria survival analysis under different environmental conditions and tested laboratory methods for bacteria removal and recovery. In a field study we distributed sterile urethane balls to children <5 from 360 households in rural India. After 24 hours, we collected and rinsed the toys in sterile water, assayed for thermotolerant coliforms (TTC) and explored associations between the level of contamination and household characteristics.

RESULTS

In the laboratory, urethane foam balls took up more indicator bacteria than the other balls. Bacteria recovery did not differ based on mechanic vs no agitation. Higher temperatures and moisture levels increased bacterial yield. In the field, the only factor associated with a decreased recovery of TTC from the balls was having a soil (unpaved) floor.

CONCLUSIONS

Sentinel toys may be an effective tool for assessing young children's exposure to faecal pathogens. However, even using methods designed to increase bacterial recovery, limited sensitivity may require larger sample sizes.

Hand-to-mouth contacts result in greater ingestion of feces than dietary water consumption in Tanzania: a quantitative fecal exposure assessment model

Diarrheal diseases kill 1800 children under the age of five die each day, and nearly half of these deaths occur in sub-Saharan Africa. Contaminated drinking water and hands are two important environmental transmission routes of diarrhea-causing pathogens to young children in low-income countries. The objective of this research is to evaluate the relative contribution of these two major exposure pathways in a low-income country setting. A Monte Carlo simulation was used to model the amount of human feces ingested by children under five years old from exposure via hand-to-mouth contacts and stored drinking water ingestion in Bagamoyo, Tanzania. Child specific exposure data were obtained from the USEPA 2011 Exposure Factors Handbook, and fecal contamination was estimated using hand rinse and stored water fecal indicator bacteria concentrations from over 1200 Tanzanian households. The model outcome is a distribution of a child's daily dose of feces via each exposure route. The model results show that Tanzanian children ingest a significantly greater amount of feces each day from hand-to-mouth contacts than from drinking water, which may help elucidate why interventions focused on water without also addressing hygiene often see little to no effect on reported incidence of diarrhea.

Comparative assessment of the bacterial communities associated with Aedes aegypti larvae and water from domestic water storage containers

Background

Domestic water storage containers constitute major Aedes aegypti breeding sites. We present for the first time a comparative analysis of the bacterial communities associated with Ae. aegypti larvae and water from domestic water containers.

Methods

The 16S rRNA-temporal temperature gradient gel electrophoresis (TTGE) was used to identify and compare bacterial communities in fourth-instar Ae. aegypti larvae and water from larvae positive and negative domestic containers in a rural village in northeastern Thailand. Water samples were cultured for enteric bacteria in addition to TTGE. Sequences obtained from TTGE and bacterial cultures were clustered into operational taxonomic units (OTUs) for analyses.

Results

Significantly lower OTU abundance was found in fourth-instar Ae. aegypti larvae compared to mosquito positive water samples. There was no significant difference in OTU abundance between larvae and mosquito negative water samples or between mosquito positive and negative water samples. Larval samples had significantly different OTU diversity compared to mosquito positive and negative water samples, with no significant difference between mosquito positive and negative water samples. The TTGE identified 24 bacterial taxa, belonging to the phyla Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and TM7 (candidate phylum). Seven of these taxa were identified in larval samples, 16 in mosquito positive and 13 in mosquito negative water samples. Only two taxa, belonging to the phyla Firmicutes and Actinobacteria, were common to both larvae and water samples. Bacilli was the most abundant bacterial class identified from Ae. aegypti larvae, Gammaproteobacteria from mosquito positive water samples, and Flavobacteria from mosquito negative water samples. Enteric bacteria belonging to the class Gammaproteobacteria were sparsely represented in TTGE, but were isolated from both mosquito positive and negative water samples by selective culture.

Conclusions

Few bacteria from water samples were identified in fourth-instar Ae. aegypti larvae, suggesting that established larval bacteria, most likely acquired at earlier stages of development, control the larval microbiota. Further studies at all larval stages are needed to fully understand the dynamics involved. Isolation of enteric bacteria from water samples supports earlier outcomes of E. coli contamination in Ae. aegypti infested domestic containers, suggesting the need to further explore the role of enteric bacteria in Ae. aegypti infestation.