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Wet markets in low-and middle-income countries are often reported to have inadequate sanitation resulting in fecal contamination of sold produce. Consumption of contaminated wet market-sourced foods has been linked to individual illness and disease outbreaks. This pilot study, conducted in two major wet markets in Dhaka city, Bangladesh during a 4-month period in 2021 aimed to assess the occurrence and characteristics of Escherichia coli and nontyphoidal Salmonella spp. (NTS) from tilapia (Oreochromis niloticus) and shrimp (Penaeus monodon). Fifty-four individuals of each species were collected. The identity of the bacterial isolates was confirmed by PCR and their susceptibility toward 15 antimicrobials was tested by disk diffusion. The whole genome of 15 E. coli and nine Salmonella spp. were sequenced using Oxford Nanopore Technology. E. coli was present in 60–74% of tilapia muscle tissue and 41– 44% of shrimp muscle tissue. Salmonella spp. was found in skin (29%) and gills (26%) of tilapia, and occasionally in muscle and intestinal samples of shrimp. The E. coli had several Multilocus sequence typing and serotypes and limited antimicrobial resistance (AMR) determinants, such as point mutations on glpT and pmrB. One E. coli (BD17) from tilapia carried resistance genes for betalactams, quinolones, and tetracycline. All the E. coli belonged to commensal phylogroups B1 and A and showed no Shiga-toxin and other virulence genes, confirming their commensal non-pathogenic status. Among the Salmonella isolates, five belonged to Kentucky serovar and had similar AMR genes and phenotypic resistance patterns. Three strains of this serovar were ST198, often associated with human disease, carried the same resistance genes, and were genetically related to strains from the region. The two undetermined sequence types of S. Kentucky were distantly related and positioned in a separate phylogenetic clade. Two Brunei serovar isolates, one Augustenborg isolate, and one Hartford isolate showed different resistance profiles. This study revealed high fecal contamination levels in tilapia and shrimp sold at two main wet markets in Dhaka. Together with the occurrence of Salmonella spp., including S. Kentucky ST198, a well-known human pathogen, these results stress the need to improve hygienic practices and sanitation standards at markets to improve food safety and protect consumer health. [ABSTRACT FROM AUTHOR]

Water quality has recently emerged as one of the utmost severe ecological problems being faced by the developing countries all over the world, and Bangladesh is no exception. Both surface and groundwater sources contain different contaminants, which lead to numerous deaths due to water-borne diseases, particularly among children. This study presents one of the most comprehensive reviews on the current status of water quality in Bangladesh with a special emphasis on both conventional pollutants and emerging contaminants. Data show that urban rivers in Bangladesh are in a critical condition, especially Korotoa, Teesta, Rupsha, Pashur, and Padma. The Buriganga River and few locations in the Turag, Balu, Sitalakhya, and Karnaphuli rivers have dissolvable oxygen (DO) levels of almost zero. Many waterways contain traces of NO3, NO2, and PO4−3 pollutants. The majority of the rivers in Bangladesh also have Zn, Cu, Fe, Pb, Cd, Ni, Mn, As, and Cr concentrations that exceed the WHO permissible limits for safe drinking water, while their metal concentrations exceed the safety threshold for irrigation. Mercury poses the greatest hazard with 90.91% of the samples falling into the highest risk category. Mercury is followed by zinc 57.53% and copper 29.16% in terms of the dangers they pose to public health and the ecosystem. Results show that a considerable percentage of the population is at risk, being exposed to contaminated water. Despite hundreds of cryptosporidiosis cases reported, fecal contamination, i.e., Cryptosporidium, is totally ignored and need serious considerations to be regularly monitored in source water. [ABSTRACT FROM AUTHOR]

Potable and equitable drinking water (DW) is a fundamental human right and essential for human health. This study is conducted to assess the groundwater and jar water quality of the roadside restaurants and tea stalls used for drinking by the local people around the Gazipur City area in Bangladesh. Water samples from 173 restaurants and tea stalls are collected. The physico‐chemical and biological parameters are analyzed according to the guidelines and standards. The results illustrate that the color, EC, and Mn of 41%, 80%, and 62% of the samples, respectively, exceed the WHO and Environmental Conservation Rules (ECR) standards. In addition, E. coli and total coliform exceeding the threshold standards are found in 47% and 64% of the water samples, respectively. The contamination of DW by fecal coliforms is confirmed and supported by prior studies, which indicates that the DW supplied in restaurants and tea stalls are unsafe because of the possible presence of pathogens. These may cause potential health hazards to consumers from various water‐borne diseases. Poor sanitation, unhygienic practices, and improper disposal of wastewater are responsible for the microbial contamination of DW. So, the authorities in charge of these places should take the right regulatory steps, such as regular sanitation inspections, DW quality monitoring, hand‐washing practices, and better sanitation in these places. [ABSTRACT FROM AUTHOR]

In Dhaka megacity (Bangladesh), lakes located in the most exclusive areas are considered crucial urban water bodies. However, these water sources are confronting a heavy load of organic and inorganic pollutants by anthropogenic activities and are being polluted continuously. In this review , 50 relevant published documents on the lake water of Dhaka megacity to highlight the overall water quality status and the potential ecological and human health risks associated with contaminations were studied. The retrieved documents were organized according to the relevant information and examined thoroughly. After a careful review, it was found that most of the lake water in Dhaka city is severely contaminated with heavy metals such as Pb, Cd, Cu, Zn, and Mn with a higher concentration of Pb and Cd than the guideline values for drinking and industrial uses. The physicochemical properties and microbial contamination with an elevated level of fecal coliforms in lake water indicate very poor water quality in all lakes. The EC and TDS in most of the lake water exceeded the standard limits with the highest EC value (4920 µS/cm) for Gulshan Lake. The indices-based water quality assessment revealed considerable heavy metal contamination in the lake's water. Few lakes are found at a minimal level of ecological risks. The assessments of health risk indicate lower non-cancer risk. Overall, it can be inferred that the lake water in the Dhaka megacity does not meet the requirements for domestic, drinking, fishing, and industrial uses. This review study will be helpful for the policymakers and environmentalists to know about the status and sources of pollution in the lake water in the megacity which in turn assist to take necessary actions to mitigate the pollution level from the studied lakes of Dhaka city, Bangladesh. [ABSTRACT FROM AUTHOR]

HEV is the most common cause of acute hepatitis globally. This review summarizes the latest knowledge on the epidemiology, clinical characteristics, testing, and treatment of HEV infection. We also focused on Bangladesh to highlight the distinct challenges and the possible remedies. In low-income settings, the virus is mainly transmitted between people by fecal contamination of drinking water causing large outbreaks, and sporadic cases. The disease is usually mild and self-limiting acute hepatitis. Still, pregnant women and their offspring in low-income countries are at particular risk for severe disease, with up to 20% maternal mortality. Despite the high burden of the disease, HEV remains a relatively neglected virus, with detection hampered by costly tests and a lack of suitable treatments. Molecular PCR diagnostics, together with ELISA antibody tests, remain the preferred methods for diagnosis of HEV; however, rapid bedside diagnostics are available and could offer a practical alternative, especially in low-income countries. One vaccine (HEV 239) is only available in China and Pakistan, as efficacy against the other genotypes remains uncertain. The effectiveness trial conducted in Bangladesh might lead the way in gathering more efficacy data and could, together with improved surveillance and raised awareness, dramatically reduce the global burden of HEV. [ABSTRACT FROM AUTHOR]

The burden of street food contamination remains significantly higher among developing countries, making its consumers' health compromised. This study aimed at identifying Escherichia coli in local street foods, track their sources and characterize their virulence properties, antimicrobial susceptibility patterns, and incidence of recent fecal contamination. Twelve E. coli isolates isolated from 28 types of street foods sold at different locations of Dhaka metropolitan city were confirmed by both culture-based and molecular methods. Phylogroup B1 of environment origin was the most predominant (58%, n=12) among the isolates, followed by commensal phylogroup A (16%), phylogroup C (8%), D (8%), and E (8%). Alarmingly, 8% of the isolates were confirmed to be Enteropathogenic E. coli (EPEC), harboring hlyA gene, and 41% were due to recent fecal contamination cases confirmed by the presence of the eae gene. Isolates showed the highest resistance to ampicillin, followed by chloramphenicol. However, resistance could not be correlated to the presence of class 1 integron as isolates sensitive to these antibiotics also harbored this mobile genetic element. The findings of this study demonstrated the presence of antibiotic-resistant, potentially pathogenic E. coli in street food which emphasizes the health hazard associated with consumption of such foods. [ABSTRACT FROM AUTHOR]

This study aimed to quantify the inequalities and identify the associated factors of the UN sustainable development goal (SDG) targets in relation to safe drinking water. The concentration of the gut bacterium Escherichia coli in drinking water at the point of use (POU) and other information were extracted from the latest wave of the nationally representative Bangladesh Multiple Indicator Cluster Survey (MICS 2019). Bivariate and multivariable multinomial logistic regression models were used to identify potential predictors of contamination, whereas, classification trees were used to determine specific combinations of background characteristics with significantly higher rates of contamination. A higher risk of contamination from drinking water was observed for households categorized as middle or low wealth who collected water from sources with higher concentrations of E. coli. Treatment of drinking water significantly reduced the risk of higher levels of contamination, whereas owning a pet was significantly associated with recontamination. Regional differences in the concentrations of E. coli present in drinking water were also observed. Interventions in relation to water sources should emphasize reducing the level of E. coli contamination. Our results may help in developing effective policies for reducing diarrheal diseases by reducing water contamination risks. [ABSTRACT FROM AUTHOR]

Shrimp is one of the major export products in South Asian countries and also an eminent source of nutrition for humans. Hence, any negative effect of this industry may affect not only the country's economy but also human health. Therefore, in this study, we aimed to assess heavy metal contamination and associated human health risks in cultured shrimp (Penaeus monodon) and aquaculture sludge collected from three shrimp farms of the Cox's Bazar district, Bangladesh. The results showed that among the eight metals studied, Pb (17.75 ± 1.5 mg/kg) and Cu (9.43 ± 2.8 mg/kg) levels in all shrimp samples were higher than the recommended limit, whereas the concentrations of Cd (0.09 ± 0.03 mg/kg), Mn (4.83 ± 2.2 mg/kg), As (0.04 ± 0.02 mg/kg), Hg (0.02 ± 0.006 mg/kg), Zn (18.89 ± 2.9 mg/kg) and Cr (0.69 ± 0.6 mg/kg) were within the permissible level. The concentrations of Mn (1043.37 ± 59.8 mg/kg), Cr (30.38 ± 2.1 mg/kg), Zn (74.72 ± 1.13 mg/kg) and Cu (31.14 ± 1.4 mg/kg) in the sludge of all farms were higher than the recommended limit, whereas the concentrations of Pb (20.23 ± 1.9 mg/kg), Cd (0.09 ± 0.2 mg/kg), As (0.44 ± 0.34 mg/kg) and Hg (0.08 ± 0.02 mg/kg) in all sludge samples were lower than the threshold limits. However, the estimated daily intake (EDI), targeted hazard quotient (THQ) and hazard index (HI) assessed for potential human health risk implications suggested that Pb and Cr may pose non-carcinogenic health effects, although carcinogenic risks (CR) values were acceptable for consumers. However, the pollution load index (PLI) of the studied area was below 1, which indicates low deterioration of the area. Geoaccumulation index (Igeo) and contamination factor (CF) analyses revealed that study area is unpolluted and sludge is enriched with metals in the following order: Mn > Zn > Cu > Cr > Cd > Hg > Pb > As. [ABSTRACT FROM AUTHOR]

Background: Antimicrobial resistance (AMR) has become an emerging threat worldwide, and developing countries such as Bangladesh are considered to be at greater risk of disseminating the resistant bacteria between human–animal interfaces. Objectives: The present study was carried out to determine the prevalence and AMR profile of Escherichia coli isolated from broiler chickens, the environment, and farmworkers. This study also aimed to identify the risk factors associated with multidrug‐resistant (MDR) E. coli infection in broiler chickens. In addition, the presence of carbapenem resistance gene (NDM‐1) was assessed. Methods: A total of 114 E. coli isolates, recovered from 150 samples (cloacal swabs = 50, farm sewage = 50, and hand washed water of farmworkers = 50) collected from 50 broiler farms, were identified by biochemical examination and polymerase chain reaction (PCR) assay. Antimicrobial susceptibility test was performed for 10 antibiotics by disk diffusion test. Carbapenem resistance gene (NDM‐1) was detected by PCR. Risk factors were identified through multivariable logistic regression. Results: The highest prevalence of E. coli was recorded in broiler chickens (86%) and the lowest in farmworkers (66%). For MDR E. coli infection, 'winter season', 'absence of specific shoes for staff', and 'use of antibiotics without veterinarian's prescription' were the significant risk factors. High resistance of the E. coli isolates was observed against levofloxacin (81.6%), doxycycline (78.1%), cefotaxime (78.1%), and ciprofloxacin (70.2%). About 76% of the isolates demonstrated MDR. None of the isolates were positive for the NDM‐1 gene. Conclusions: The high level and similar pattern of antibiotic resistance in E. coli isolates from broiler chickens, farmworkers, and sewage in poultry farms indicates a good possibility of spreading the antibiotic‐resistant E. coli in such settings. [ABSTRACT FROM AUTHOR]

Health, and in turn income and welfare, depend on access to safe drinking water. Although the majority of rural households worldwide obtain drinking water from community water sources, there is limited evidence about how effectively these sources provide safe drinking water. This study combines a randomized experiment with water quality testing to evaluate the impact of a program that provides community deep tubewells in rural Bangladesh. The program reduces exposure to arsenic, a major natural pollutant, but not fecal contamination. Households may use fewer sources with fecal contamination, but any such effects are offset by recontamination through transport and possibly storage. The results suggest that while community deep-tubewell construction programs may reduce exposure to arsenic in Bangladesh, reducing exposure to fecal contamination may require interventions that go beyond community sources. [ABSTRACT FROM AUTHOR]

Hepatitis E virus (HEV) infection is a significant public health issue in many developing countries, causing waterborne outbreaks as well as sporadic hepatitis. We report here an outbreak of HEV genotype 1f infection during April–May 2018 among people living at Halisohor, a low land in the southern part of Chottogram District of Bangladesh. A total of 933 patients were admitted to Combined Military Hospital (CMH), Chottogram, with symptoms of acute hepatitis. Among them, 550 patients were tested by ELISA for HEV‐specific (IgM) and all were positive. Genotyping, sequencing, and phylogenetic analysis based on ORF2 region revealed that the outbreak was caused by genotype 1f and the strains were closely related to the previously reported HEV strains that caused the outbreak in Bangladesh in 2010. The current outbreak was most likely linked with water supply as fecal contamination in water was evident and could be prevented by ensuring access to safe drinking water. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 log10E. 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. [ABSTRACT FROM AUTHOR]

Background: Hands are a route of transmission for fecal-oral pathogens. This analysis aimed to assess associations between hand E. coli contamination and child age and determine if observed hand cleanliness can serve as a proxy for E. coli contamination on young children’s hands. Methods: Trained field workers collected hand rinse samples from children aged 1–14 months in 584 households in rural Bangladesh and assessed the visual cleanliness of child hands (fingernails, finger pads and palms). Samples were analyzed using the IDEXX most probable number (MPN) methodto enumerate E. coli. We assessed if child age (immobile children aged 1–4 months vs. mobile children aged 5–14 months) is associated with log10 E. coli counts on hands using generalized estimating equations (GEE). We estimated the log10 difference in hand E. coli counts associated with the cleanliness of different hand parts using a multivariable GEE model.We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for dirty fingernails, fingerpads, palms and overall hands (the three observed parts combined) against binary E. coli presence on hands. Results: E. coli was detected on 43% of child hands. Children in the mobile age range had 0.17 log10 MPN higher E. coli on hands than those in the immobile age range (Δlog10 = 0.17, 95% CI = 0.02, 0.32, p = 0.03). Children with visible dirt particles on finger pads had 0.46 log10 MPN higher E. coli on hands than those with clean finger pads (Δlog10 = 0.46, 95% CI = 0.05, 0.87, p = 0.03). Dirty fingernails indicated binary E. coli presence with 81% sensitivity and 26% specificity while dirty fingerpads and palms indicated E. coli presence with 29% sensitivity and 75–77% specificity. The PPV was 45–48% and NPV 59–65% for all three types of observations. Conclusion: Hand contamination with E. coli was prevalent among young children in rural Bangladesh, with higher levels of contamination among mobile children. Studies should assess if strategies to remove animal feces from the courtyard, provide designated hygienic play spaces for children and deliver targeted messaging to mothers to wipe or wash children’s hands after contact with animals and animal feces reduce child hand contamination. Visible hand cleanliness was a poor predictor of E. coli presence on young children’s hands so other low-cost field measurements are needed to accurately detect fecal contamination on hands. [ABSTRACT FROM AUTHOR]

Abstract Bangladesh is a deltaic country and is highly vulnerable to climate change and sea level rise. This study explores population migration risk in relation to communal crisis due to socioeconomic vulnerability, drinking water scarcity, and health threats caused by salinity hazards. For this, we conducted a household questionnaire survey as well as, focus group discussions, key informant interviews, and field observations. To identify the drinking water salinity and migration risk, our theoretical process hypothesizes a new composite indexing approach. Salinity hazards and potable water crises have increased the spread of human diseases and treatment costs, while socioeconomic crisis and poverty are inseparable risks of coastal communities because of frequent cyclone hits. Recently, salinity hazards have added a new dimension to health insecurities and household financial instability. Results showed a high migration risk in the unions of Gabura, Munshigonj, Atulia, Burigoaliny, and Padmapukur (from highest risk to lowest), as these areas exhibit worsening situations with respect to drinking water scarcity, salinity hazards, and health hazards, and their adaptive capacities are significantly low. Furthermore, socioeconomic vulnerabilities to cyclone hits, salinity hazards, and severe drinking water scarcity may soon contribute to increased population migration in response to climate change, sea level rise, and the associated impacts of these trends. To tackle the future mass population migration problem, urgent action is required to improve socioeconomic conditions, and provide alternative sources of potable water and health care facilities. Hard and soft measures must be ensured to reconstruct vulnerable areas impacted by riverbank erosion, flooding, and waterlogging. Additionally, action should be taken to enhance local awareness of coastal disasters, their associated hazardous consequences, and possible mitigation and adaptation measures. Highlights • Salinity intrusion creates a severe drinking water crisis and causes public health problems. • Additional health expenditures exert pressure on the economy of disaster-affected coastal households. • Population migration risk was estimated using a new migration risk estimation technique. • Strong migration risk values were found at the community level. [ABSTRACT FROM AUTHOR]

Surface waters in Bangladesh and many developing countries are characterized by high concentrations of organic matter and ammonia, particularly during the dry season. In the presence of high concentration of ammonia, break point chlorination often becomes impractical at treatment plant because of very high chlorine dose requirements; therefore, “chloramination” (i.e., chlorination at chlorine to ammonia ratio below “break point”) is most often carried out. It has been found that “chloramination” at low chlorine to ammonia molar ratios (e.g., less than 0.6:1.0) could be effective for disinfection for water containing lower level of fecal contamination, even when initial ammonia concentration is relatively low. However, “chloramination” may not be effective for water with higher level of fecal contamination. Even before breakpoint is reached, a noticeable amount of free chlorine has been found to exist in water; and both mono-chloramine and this free chlorine act as disinfectant. For a known initial ammonia concentration, the optimum disinfection should be achieved at chlorine to ammonia weight ratio of around 5.0:1.0 to 6.25:1.0. But if ammonia concentration in water is high, chloramination at such chlorine to ammonia ratio would produce very high concentrations of chloramines, exceeding the WHO/USEPA guideline values. For water with such high initial ammonia concentration, a lower “chlorine to ammonia” ratio should be considered for chloramination. [ABSTRACT FROM AUTHOR]

Since May 2006, the BRAC Water, Sanitation and Hygiene (WASH) Programme in Bangladesh has enabled more than 30 million people to achieve hygienic sanitation, contributing to an increase in sanitation coverage from 33 to 83% in programme areas and rapid progress towards universal access. In rural areas, most families have single pit latrines that need to be emptied when full. Since 2007, BRAC has promoted the use of hygienic double-pit latrines. Use of double-pit latrines, where appropriate, is also recommended in the Bangladeshi Draft National Water Supply and Sanitation Strategy. More than 800,000 double-pit latrines are in use in BRAC WASH areas, delaying the need for emptying and allowing time for the fecal matter to decompose while the resting pit is sealed. This paper focuses on a study undertaken by BRAC WASH to treat and safely use fecal material from double pit latrines as an organic fertilizer for rice and other crops. The study investigated the removal of pathogens from pit waste through simple solar drying and conducted analysis on nutrient properties of fecal sludge. The study showed a significant positive impact on developing organic fertilizer from fecal sludge. [ABSTRACT FROM AUTHOR]

Background: Household-level sanitation interventions have had limited effects on child health or environmental contamination, potentially due to low community coverage. Higher community-level coverage with safely managed sanitation can reduce opportunities for disease transmission.Methods: We estimated associations between community sanitation coverage, environmental fecal contamination, and child health among 360 compounds in the control arm of the WASH Benefits trial in rural Bangladesh (NCT01590095). In each compound, we enumerated E. coli in environmental samples and recorded the 7-day prevalence of caregiver-reported diarrheal disease and acute respiratory infections (ARI) in children under five. We observed indicators of latrine access and quality among all neighboring compounds within 100 m of study compounds. We defined community coverage as the proportion of neighboring compounds with (1) at least one latrine, and (2) exclusively hygienic latrines (improved facility observed to safely contain feces), within both 50 m and 100 m of study compounds. We assessed effect modification by population density and season.Results: Adjusted for confounders, study compounds surrounded by 100% coverage of at least one latrine per compound within 50 m had slightly lower log10E. coli counts in stored water (Δlog = -0.13, 95% CI -0.26, -0.01), child hand rinses (Δlog = -0.13, 95% CI -0.24, -0.02), and caregiver hand rinses (Δlog = -0.16, 95% CI -0.29, -0.03) and marginally lower prevalence of diarrheal disease (prevalence ratio [PR] = 0.82, 95% CI 0.64, 1.04) and ARI (PR = 0.84, 95% CI 0.69, 1.03) compared to compounds surrounded by <100% coverage. Effects were similar but less pronounced at 100 m. At higher population densities, community latrine coverage was associated with larger reductions in E. coli on child and caregiver hands and prevalence of diarrheal disease. Coverage with exclusively hygienic latrines was not associated with any outcome.Conclusion: Higher community sanitation coverage was associated with reduced fecal contamination and improved child health, with stronger effects at highly local scales (50m) and at high population densities. Our findings indicate that the relationship between community sanitation coverage, environmental contamination, and child health varies by definition of coverage, distance, and population density. This work highlights significant uncertainty around how to best measure sanitation coverage and the expected health effects of increasing sanitation coverage using a specific metric. Better understanding of community-level sanitation access is needed to inform policy for implementing sanitation systems that effectively protect community health. [ABSTRACT FROM AUTHOR]

Background: Vibrio cholerae infections cluster in households. This study's objective was to quantify the relative contribution of direct, within-household exposure (for example, via contamination of household food, water, or surfaces) to endemic cholera transmission. Quantifying the relative contribution of direct exposure is important for planning effective prevention and control measures. Methodology/Principal Findings: Symptom histories and multiple blood and fecal specimens were prospectively collected from household members of hospital-ascertained cholera cases in Bangladesh from 2001–2006. We estimated the probabilities of cholera transmission through 1) direct exposure within the household and 2) contact with community-based sources of infection. The natural history of cholera infection and covariate effects on transmission were considered. Significant direct transmission (p-value<0.0001) occurred among 1414 members of 364 households. Fecal shedding of O1 El Tor Ogawa was associated with a 4.9% (95% confidence interval: 0.9%–22.8%) risk of infection among household contacts through direct exposure during an 11-day infectious period (mean length). The estimated 11-day risk of O1 El Tor Ogawa infection through exposure to community-based sources was 2.5% (0.8%–8.0%). The corresponding estimated risks for O1 El Tor Inaba and O139 infection were 3.7% (0.7%–16.6%) and 8.2% (2.1%–27.1%) through direct exposure, and 3.4% (1.7%–6.7%) and 2.0% (0.5%–7.3%) through community-based exposure. Children under 5 years-old were at elevated risk of infection. Limitations of the study may have led to an underestimation of the true risk of cholera infection. For instance, available covariate data may have incompletely characterized levels of pre-existing immunity to cholera infection. Transmission via direct exposure occurring outside of the household was not considered. Conclusions: Direct exposure contributes substantially to endemic transmission of symptomatic cholera in an urban setting. We provide the first estimate of the transmissibility of endemic cholera within prospectively-followed members of households. The role of direct transmission must be considered when planning cholera control activities. Author Summary: Since John Snow's ground-breaking investigations of the devastating outbreaks in 19th-century London, cholera has been considered the quintessential waterborne human infection, transmitting via fecal contamination of environmental water sources. Recently, renewed interest has been paid to the potential importance of transmission through direct exposure within close-contact groups, such as, via fecal contamination of surfaces, food, or drinking water within households. Significant direct transmission of cholera within close contact groups would represent a new target for innovative prevention and control strategies. We estimated the probability of transmission 1) via direct contact within 364 urban households located in an endemic cholera setting (Dhaka, Bangladesh) and 2) via exposure to sources located outside of these households. In this setting we estimated a 4 to 8 percent probability of becoming infected with cholera via direct exposure within households in this setting versus a 2 to 3 percent likelihood of infection due to exposure to external sources over a comparable time period. Our results demonstrate that direct (within-household) transmission is a significant component of endemic cholera transmission, suggesting that biomedical and behavioral-modification interventions specifically targeting this mode of transmission could substantially reduce the cholera burden in this type of setting. [ABSTRACT FROM AUTHOR]

Diarrheal diseases are endemic in Bangladesh, where sanitation is poor, and untreated drinking water extracted from shallow (<43 m) tubewells could partially contribute to disease propagation. This study measures the effects of local population–environment context on tubewell water quality and diarrheal disease incidence. The study site includes six villages in Matlab, Bangladesh, with approximately 12,000 residents. Study data include monthlyEscherichia coliconcentrations for 100 wells, monthly diarrheal events for all children under five, and a detailed water and sanitation infrastructure database created through a submeter accuracy Global Positioning System survey. We developed sanitation metrics to measure the relationship between tubewell water fecal contamination and estimates of human fecal loadings at varying scales. The relationship between childhood diarrhea andE. coliin drinking water was measured for households that obtained drinking water from survey wells. Results show that tubewells surrounded by unsanitary latrines, latrine-polluted ponds, and higher population densities were more frequently contaminated with fecal coliforms. The analysis also showed that poor sanitation infrastructure might affect childhood diarrheal disease via tubewell contamination. Our findings shed light on the importance of integrating population and environment data to identify circumstances in which shallow well water quality is compromised and children are put at risk of contracting diarrheal diseases. Sanitation interventions should highlight the spatial separation of latrines and drinking water wells to limit contamination. [ABSTRACT FROM PUBLISHER]

Ponds receiving latrine effluents may serve as sources of fecal contamination to shallow aquifers tapped by millions of tube-wells in Bangladesh. To test this hypothesis, transects of monitoring wells radiating away from four ponds were installed in a shallow sandy aquifer underlying a densely populated village and monitored for 14 months. Two of the ponds extended to medium sand. Another pond was sited within silty sand and the last in silt. The fecal indicator bacterium E. coli was rarely detected along the transects during the dry season and was only detected near the ponds extending to medium sand up to 7 m away during the monsoon. A log-linear decline in E. coli and Bacteroidales concentrations with distance along the transects in the early monsoon indicates that ponds excavated in medium sand were the likely source of contamination. Spatial removal rates ranged from 0.5 to 1.3 log10/m. After the ponds were artificially filled with groundwater to simulate the impact of a rain storm, E. coli levels increased near a pond recently excavated in medium sand, but no others. These observations show that adjacent sediment grain-size and how recently a pond was excavated influence the how much fecal contamination ponds receiving latrine effluents contribute to neighboring groundwater. [ABSTRACT FROM AUTHOR]

Abstract: A majority of households in Bangladesh rely on pond water for hygiene. Exposure to pond water fecal contamination could therefore still contribute to diarrheal disease despite the installation of numerous tubewells for drinking. The objectives of this study are to determine the predominant sources (human or livestock) of fecal pollution in ponds and examine the association between local population, latrine density, latrine quality and concentrations of fecal bacteria and pathogens in pond water. Forty-three ponds were analyzed for E. coli using culture-based methods and E. coli, Bacteroidales and adenovirus using quantitative PCR. Population and sanitation spatial data were collected and measured against pond fecal contamination. Humans were the dominant source of fecal contamination in 79% of the ponds according to Bacteroidales measurements. Ponds directly receiving latrine effluent had the highest concentrations of fecal indicator bacteria (up to 106 Most Probable Number (MPN) of culturable E. coli per 100mL). Concentrations of fecal indicator bacteria correlated with population surveyed within a distance of 30–70m (p<0.05) and total latrines surveyed within 50–70m (p<0.05). Unsanitary latrines (visible effluent or open pits) within the pond drainage basin were also significantly correlated to fecal indicator concentrations (p<0.05). Water in the vast majority of the surveyed ponds contained unsafe levels of fecal contamination attributable primarily to unsanitary latrines, and to lesser extent, to sanitary latrines and cattle. Since the majority of fecal pollution is derived from human waste, continued use of pond water could help explain the persistence of diarrheal disease in rural South Asia. [Copyright &y& Elsevier]

The health risks of As exposure due to the installation of millions of shallow tubewells in the Bengal Basin are known, but fecal contamination of shallow aquifers has not systematically been examined. This could be a source of concern in densely populated areas with poor sanitation because the hydraulic travel time from surface water bodies to shallow wells that are low in As was previously shown to be considerably shorter than for shallow wells that are high in As. In this study, 125 tubewells 6-36 m deep were sampled in duplicate for 18 months to quantify the presence of the fecal indicator Escherichia coli. On any given month, E. coli was detected at levels exceeding 1 most probable number per 100 mL in 19-64% of all shallow tubewells, with a higher proportion typically following periods of heavy rainfall. The frequency of E. coli detection averaged over a year was found to increase with population surrounding a well and decrease with the As content of a well, most likely because of downward transport of E. coli associated with local recharge. The health implications of higher fecal contamination of shallow tubewells, to which millions of households in Bangladesh have switched in order to reduce their exposure to As, need to be evaluated. [ABSTRACT FROM AUTHOR]

We introduced flocculant-disinfectant water treatment for 12 weeks in 103 households in Bangladesh to assess if drinking water would be chemically and microbiologically improved and the body burden of arsenic reduced. The median concentration of arsenic in tubewell water decreased by 88% after introduction of the flocculant-disinfectant from 136 μg/l at baseline to 16 (p < 0.001). The median concentration of total urinary arsenic decreased 42% from 385 μg/g creatinine at baseline to 225 μg/g creatinine after intervention (p < 0.001). Among 206 post-intervention drinking water samples that were reportedly treated on the date the sample was collected, 99 (48%) lacked residual free chlorine and 100 (49%) were contaminated with thermotolerant coliforms. The flocculant-disinfectant markedly reduced arsenic in drinking water, but treated drinking water was frequently contaminated with fecal organisms. The lesser reduction in urinary arsenic compared to water arsenic and the health consequences of this reduction require further research. [ABSTRACT FROM AUTHOR]

• Simulated the choice to drink chlorinated water based on taste in Dhaka, Bangladesh • A dose of 0.5 mg/L Cl 2 minimizes simulated exposure to E. coli • A dose of 1-2 mg/L Cl 2 maximizes simulated exposure to trihalomethanes • Behavior changes the expected relation between dose and microbial and DBP exposure • Taste acceptability is critical for establishing chlorination doses [Display omitted] Expanding drinking water chlorination could substantially reduce the burden of disease in low- and middle-income countries, but the taste of chlorinated water often impedes adoption. We developed a Monte Carlo simulation to estimate the effect of people's choice to accept or reject drinking water based on chlorine taste and their subsequent exposure to E. coli and trihalomethanes, a class of disinfection byproduct (DBP). The simulation used empirical data from Dhaka, Bangladesh, a megacity with endemic waterborne disease. We drew on published taste acceptability thresholds from Dhaka residents, measured residual chlorine and thermotolerant E. coli inactivation following the addition of six chlorine doses (0.25–3.0 mg/L as Cl 2) to untreated piped water samples from 100 locations, and analyzed trihalomethane formation in 54 samples. A dose of 0.5 mg/L, 75% lower than the 2 mg/L dose typically recommended for household chlorination of low-turbidity waters, minimized overall exposure to E. coli. Doses of 1–2 mg/L maximized overall exposure to trihalomethanes. Accounting for chlorine taste aversion indicates that microbiological exposure increases and DBP exposure decreases above certain doses as a higher proportion of people reject chlorinated water in favor of untreated water. Taken together with findings from other modeling analyses, empirical studies, and field trials, our results suggest that taste acceptability should be a critical consideration in establishing chlorination dosing guidelines. Particularly when chlorination is first implemented in water supplies with low chlorine demand, lower doses than those generally recommended for household water treatment can help avoid taste-related objections while still meaningfully reducing contaminant exposure. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the water quality of piped-to-plot source water with point-of-drinking water in the households of a low-income urban area in Bangladesh. A total of 430 low-income households and 78 communal sources connected to these households were selected from the East Arichpur area of Dhaka. The water samples were collected from point-of-drinking vessels (household members' preferred drinking vessels i.e., a mug, glass, or bottle) in households and from linked sources at six-week intervals between September 2014 and December 2015. Water samples were processed using standard membrane filtration and culture methods to quantify E. coli. Analysis of paired data from source and point-of-drinking water collected on the same day showed that fecal contamination increased from source to point-of-drinking water in the households in 51% (626/1236) of samples. Comparison between bottles vs. other wide-mouth vessels (i.e., glasses, mugs, jugs) showed significantly lower odds (p = 0.000, OR = 0.58, (0.43–0.78)) of fecal contamination compared to other drinking vessels. The findings suggest that recontamination and post-treatment contamination at the point of drinking play a significant role in water contamination in households. Hygiene education efforts in the future should target the promotion of narrow-mouth drinking vessels to reduce contamination. [ABSTRACT FROM AUTHOR]

• Building resilience and developing stewardship strategies is crucial for coastal agricultural systems. • Resilience assessment for coastal agricultural systems in Bangladesh is carried out based on indicator-based approach. • One-fifths of the coastal farmers have ability to recover, reorganise and evolve following shocks and stresses. • Agroecosystem stewardship strategies are developed through principal component analysis. • The results are intended to be used for contributing to coastal adaptation planning in Bangladesh. Assessments of "resilience" are becoming a priority across multiple sectors. Specifically, the coastal agricultural system in Bangladesh faces a multitude of problems such as sea level rise. Building resilience for this system is thus important in accelerating the country's socio-economic development. Therefore, the objectives of this study are (a) to assess resilience of coastal agricultural systems and (b) to develop coastal agroecosystem stewardship strategies in Bangladesh. Resilience was assessed quantitatively, based on an established framework that includes three capacities (i.e., absorptive, adaptive and transformative) and five dimensions, namely, social, economic, ecological, physical and institutional. Fifteen indicators were developed by applying an assemblage of top-down and bottom-up approaches. A structured questionnaire was used to survey 330 households from 15 villages in five coastal sub-districts. The percentile value of composite resilience indices revealed that one-fifths of the coastal farmers (or households) had a mixed ability (e.g., fish farming skills) and capacity (e.g., better decision-making) to recover, reorganise and evolve following shocks (e.g., flash flood) and stresses (e.g., water logging). Following resilience assessment, five coastal agroecosystem stewardship strategies (facilitating adaptive agricultural governance; promoting economic and ecological diversity; fostering social learning; investing in coastal infrastructure; and increasing agricultural productivity) are developed based on principal component analysis. The methods of objectively developing stewardship strategies can be replicable to other coastal areas. The findings of this study are intended to be used for contributing to coastal adaptation planning in Bangladesh, especially for the Delta Plan 2100. [ABSTRACT FROM AUTHOR]

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 log 10 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.