Nontarget Analysis of Polluted Surface Waters in Bangladesh Using Open Science Workflows.

Nontarget mass spectrometry has great potential to reveal patterns of water contamination globally through community science, but few studies are conducted in low-income countries, nor with open-source workflows, and few datasets are FAIR (Findable, Accessible, Interoperable, Reusable). Water was collected from urban and rural rivers around Dhaka, Bangladesh, and analyzed by liquid chromatography high-resolution mass spectrometry in four ionization modes (electrospray ionization ±, atmospheric pressure chemical ionization ±) with data-independent MS2 acquisition. The acquisition strategy was complementary: 19,427 and 7365 features were unique to ESI and APCI, respectively. The complexity of water pollution was revealed by >26,000 unique molecular features resolved by MS-DIAL, among which >20,000 correlated with urban sources in Dhaka. A major wastewater treatment plant was not a dominant pollution source, consistent with major contributions from uncontrolled urban drainage, a result that encourages development of further wastewater infrastructures. Matching of deconvoluted MS2 spectra to public libraries resulted in 62 confident annotations (i.e., Level 1-2a) and allowed semiquantification of 42 analytes including pharmaceuticals, pesticides, and personal care products. In silico structure prediction for the top 100 unknown molecular features associated with an urban source allowed 15 additional chemicals of anthropogenic origin to be annotated (i.e., Level 3). The authentic MS2 spectra were uploaded to MassBank Europe, mass spectral data were openly shared on the MassIVE repository, a tool (i.e., MASST) that could be used for community science environmental surveillance was demonstrated, and current limitations were discussed.

Ruminants Contribute Fecal Contamination to the Urban Household Environment in Dhaka, Bangladesh.

In Dhaka, Bangladesh, the sensitivity and specificity of three human, three ruminant, and one avian source-associated QPCR microbial source tracking assays were evaluated using fecal samples collected on site. Ruminant-associated assays performed well, whereas the avian and human assays exhibited unacceptable cross-reactions with feces from other hosts. Subsequently, child hand rinses (n = 44) and floor sponge samples (n = 44) from low-income-households in Dhaka were assayed for fecal indicator bacteria (enterococci, Bacteroidales, and Escherichia coli) and a ruminant-associated bacterial target (BacR). Mean enterococci concentrations were of 100 most probable number (MPN)/2 hands and 1000 MPN/225 cm(2) floor. Mean concentrations of Bacteroidales were 10(6) copies/2 hands and 10(5) copies/225 cm(2) floor. E. coli were detected in a quarter of hand rinse and floor samples. BacR was detected in 18% of hand rinse and 27% of floor samples. Results suggest that effective household fecal management should account not only for human sources of contamination but also for animal sources. The poor performance of the human-associated assays in the study area calls into the question the feasibility of developing a human-associated marker in urban slum environments, where domestic animals are exposed to human feces that have been disposed in pits and open drains.

Toys and toilets: cross-sectional study using children's toys to evaluate environmental faecal contamination in rural Bangladeshi households with different sanitation facilities and practices.

OBJECTIVE: To evaluate household faecal contamination using children's toys among 100 rural Bangladeshi households categorised as 'cleaner' (toilet that reliably separates faeces from the environment and no human faeces in/around living space) or 'less clean' (no toilet or toilet that does not reliably separate faeces from the environment and human faeces in/around living space). METHODS: We distributed toy balls to each household and rinsed each study toy and a toy already owned by the household in 200 ml of Ringer's solution. We enumerated faecal coliforms and faecal streptococci from each rinse using membrane filtration methods. RESULTS: Study toys from 39 cleaner households had lower mean faecal coliform contamination than toys from 61 less clean households (2.4 log10 colony-forming units (CFU)/200 ml vs. 3.2 log10 CFU/200 ml, P = 0.03). However, wealth measures explained a portion of this relationship. Repeat measures were moderately variable [coefficient of variation (CV) = 6.5 between two toys in the household at the same time, CV = 37.6 between toys in the household at two different times 3-4 days apart]. Too few households owned a non-porous toy to compare groups without risk of bias. CONCLUSION: In rural Bangladesh, improved sanitation facilities and practices were associated with less environmental contamination. Whether this association is independent of household wealth and whether the difference in contamination improves child health merit further study. The variation found was typical for measures of environmental contamination, and requires large sample sizes to ascertain differences between groups with statistical significance.

The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits.

BACKGROUND: Recent phase-contrast X-ray imaging studies suggest that inspiration primarily drives lung aeration and airway liquid clearance at birth, which questions the role of adrenaline-induced activation of epithelial sodium channels (ENaCs). We hypothesized that pressures generated by inspiration have a greater role in airway liquid clearance than do ENaCs after birth. METHODS: Rabbit pups (30 d of gestation) were delivered and sedated, and 0.1 ml of saline (S) or amiloride (Am; an ENaC inhibitor) was instilled into the lungs before mechanical ventilation. Two other groups (30 d of gestation) were treated similarly but were also given adrenaline (S/Ad and Am/Ad) before mechanical ventilation. RESULTS: Amiloride and adrenaline did not affect functional residual capacity (FRC) recruitment (P > 0.05). Amiloride increased the rate of FRC loss between inflations (Am: -5.2 ± 0.6 ml/kg/s), whereas adrenaline reduced the rate of FRC loss (S/Ad: -1.9 ± 0.3 ml/kg/s) as compared with saline-treated controls (S: -3.5 ± -0.6 ml/kg/s; P < 0.05). CONCLUSION: These data indicate that inspiration is a major determinant of airway liquid clearance and FRC development during positive pressure ventilation. Although ENaC inhibition and adrenaline administration had no detectable effect on FRC development, ENaC may help to prevent liquid from re-entering the airways during expiration.

Surfactant increases the uniformity of lung aeration at birth in ventilated preterm rabbits.

Surfactant deficiency is a major cause of respiratory failure in newborns. We have investigated the roles of surfactant and positive end-expiratory pressure (PEEP) in the development of a functional residual capacity (FRC) and the distribution of ventilation at birth. Preterm rabbit pups (28 d GA) were delivered and received either saline or surfactant and then ventilated with (3PEEP) or without (0PEEP) 3 cm H2O PEEP (groups: saline/0PEEP, surfactant/0PEEP, saline/3PEEP, surfactant/3PEEP). Lung gas volumes were measured using plethysmography, and the uniformity of ventilation was analyzed using phase contrast (PC) x-ray imaging. Surfactant/0PEEP pups had greater FRCs and the lungs were more uniformly ventilated than saline/0PEEP pups; FRC at inflation 19-21 was 2.46 ± 0.52 mL/kg versus 0.91 ± 0.95 mL/kg (p < 0.05). Saline/3PEEP pups developed an FRC of 7.54 ± 1.68 mL/kg at inflation 19-21 (p < 0.05), but the distribution of ventilation was initially nonuniform. Surfactant/3PEEP pups had an FRC of 8.50 ± 0.80 mL/kg (at inflation 19-21), and the distribution of ventilation was more uniform than with saline/3PEEP (p < 0.05). In ventilated preterm newborn rabbits, PEEP has a greater effect on FRC than surfactant, although the two are additive. Surfactant, administered at birth, markedly improved the uniformity of ventilation irrespective of whether PEEP was applied.

The 2008 cholera epidemic in Zimbabwe: experience of the icddr,b team in the field.

During August 2008-June 2009, an estimated 95,531 suspected cases of cholera and 4,282 deaths due to cholera were reported during the 2008 cholera outbreak in Zimbabwe. Despite the efforts by local and international organizations supported by the Zimbabwean Ministry of Health and Child Welfare in the establishment of cholera treatment centres throughout the country, the case-fatality rate (CFR) was much higher than expected. Over two-thirds of the deaths occurred in areas without access to treatment facilities, with the highest CFRs (>5%) reported from Masvingo, Manicaland, Mashonaland West, Mashonaland East, Midland, and Matabeleland North provinces. Some factors attributing to this high CFR included inappropriate cholera case management with inadequate use of oral rehydration therapy, inappropriate use of antibiotics, and a shortage of experienced healthcare professionals. The breakdown of both potable water and sanitation systems and the widespread contamination of available drinking-water sources were also considered responsible for the rapid and widespread distribution of the epidemic throughout the country. Training of healthcare professionals on appropriate cholera case management and implementation of recommended strategies to reduce the environmental contamination of drinking-water sources could have contributed to the progressive reduction in number of cases and deaths as observed at the end of February 2009.

Environmental reservoirs of Vibrio cholerae.

The environmental reservoir of Vibrio cholerae, the causative agent of cholera, has been a topic of scientific investigation ever since the discovery of the bacterium itself. While the bacteria can be isolated from both clinical and environmental sources during epidemics, it evades isolation by conventional culture techniques during the period between successive epidemics. The problem is identifying the location and mode of survival and multiplication of V. cholerae during this inter-epidemic period. This information is crucial not only for epidemiological reasons, but also because the seasonality of cholera epidemics is plausibly mediated by the climate-regulated activity of the reservoir. This article focuses on the epidemiological importance of the environmental reservoir of V. cholerae, considering several investigations made on different types of aquatic fauna (zooplanktons, crustaceans, etc.) and flora (macrophytes and microphytes). After evaluating different lines of evidence, we make the case that certain species of cyanobacteria (Anabaena variabilis, Microcystis aeruginosa) can act as inter-epidemic reservoirs of V. cholerae. Physiological and functional aspects of this association are also discussed. We then present a hypothesis, expanding upon a previously published conceptual model, of how the climate-regulated seasonality of cholera epidemics is mediated by the effect of climatic factors on algal bloom and other local abiotic variables in the water, using Bangladesh as a model. Finally, another aspect of the climate-dependence of disease patterns is briefly explored: large-scale environmental signatures associated with cholera, and recent modelling efforts to predict cholera outbreaks based on coastal phytoplankton. The review, therefore, serves not only as a study of the identity of the inter-epidemic reservoir of V. cholerae, but also explores different ways in which the reservoir and the pathogen behaviour is affected by the climate, and the possible consequences it may have on disease pattern.

Seasonality of cholera from 1974 to 2005: a review of global patterns.

BACKGROUND: The seasonality of cholera is described in various study areas throughout the world. However, no study examines how temporal cycles of the disease vary around the world or reviews its hypothesized causes. This paper reviews the literature on the seasonality of cholera and describes its temporal cycles by compiling and analyzing 32 years of global cholera data. This paper also provides a detailed literature review on regional patterns and environmental and climatic drivers of cholera patterns. DATA, METHODS, AND RESULTS: Cholera data are compiled from 1974 to 2005 from the World Health Organization Weekly Epidemiological Reports, a database that includes all reported cholera cases in 140 countries. The data are analyzed to measure whether season, latitude, and their interaction are significantly associated with the country-level number of outbreaks in each of the 12 preceding months using separate negative binomial regression models for northern, southern, and combined hemispheres. Likelihood ratios tests are used to determine the model of best fit. The results suggest that cholera outbreaks demonstrate seasonal patterns in higher absolute latitudes, but closer to the equator, cholera outbreaks do not follow a clear seasonal pattern. CONCLUSION: The findings suggest that environmental and climatic factors partially control the temporal variability of cholera. These results also indirectly contribute to the growing debate about the effects of climate change and global warming. As climate change threatens to increase global temperature, resulting rises in sea levels and temperatures may influence the temporal fluctuations of cholera, potentially increasing the frequency and duration of cholera outbreaks.

Seaweeds as a reservoir for diverse Vibrio parahaemolyticus populations in Japan.

Gastroenteritis caused by Vibrio parahaemolyticus has recently been associated with foods prepared with seaweeds, but little is known about the bacterium's abundance and diversity among seaweeds in coastal environment. Therefore, we determined its phenotypic and genotypic diversity in relation to its seasonal abundance in seawater and seaweed samples from three areas of Kii Channel, Japan during June 2003 to May 2004. Isolates were obtained by selective enrichment of samples and detection of V. parahaemolyticus by colony hybridization with a species-specific probe. A total of 128 isolates comprising 16 from each source in each season were characterized by serotyping and ribotyping. V. parahaemolyticus was more abundant in seaweeds (3,762 isolates) than in water samples (2,238 isolates). Twenty and 17 serotypes were found among the selected seaweed and seawater isolates, respectively. Cluster analysis revealed 19, 11, 7 and 9 ribotypes during summer, autumn, winter and spring, respectively. Seaweeds supported a diverse V. parahaemolyticus population throughout the year and thus seaweeds are a reservoir for the organism. However, V. parahaemolyticus occurrence had positive correlation with water temperature and its abundance in seaweeds was at least 50 times higher during summer than in winter.

The public health significance of latrines discharging to groundwater used for drinking.

Faecal contamination of groundwater from pit latrines is widely perceived as a major threat to the safety of drinking water for several billion people in rural and peri-urban areas worldwide. On the floodplains of the Ganges-Brahmaputra-Meghna delta in Bangladesh, we constructed latrines and monitored piezometer nests monthly for two years. We detected faecal coliforms (FC) in 3.3-23.3% of samples at four sites. We differentiate a near-field, characterised by high concentrations and frequent, persistent and contiguous contamination in all directions, and a far-field characterised by rare, impersistent, discontinuous low-level detections in variable directions. Far-field FC concentrations at four sites exceeded 0 and 10 cfu/100 ml in 2.4-9.6% and 0.2-2.3% of sampling events respectively. The lesser contamination of in-situ groundwater compared to water at the point-of-collection from domestic wells, which itself is less contaminated than at the point-of-consumption, demonstrates the importance of recontamination in the well-pump system. We present a conceptual model comprising four sub-pathways: the latrine-aquifer interface (near-field); groundwater flowing from latrine to well (far-field); the well-pump system; and post-collection handling and storage. Applying a hypothetical dose-response model suggests that 1-2% of the diarrhoeal disease burden from drinking water is derived from the aquifer, 29% from the well-pump system, and 70% from post-collection handling. The important implications are (i) that leakage from pit latrines is a minor contributor to faecal contamination of drinking water in alluvial-deltaic terrains; (ii) fears of increased groundwater pollution should not constrain expanding latrine coverage, and (iii) that more attention should be given to reducing contamination around the well-head.

Safe distances between groundwater-based water wells and pit latrines at different hydrogeological conditions in the Ganges Atrai floodplains of Bangladesh.

BACKGROUND: Groundwater drawn from shallow tubewells in Bangladesh is often polluted by nearby pit latrines, which are commonly used toilets in rural and sub-urban areas of the country. METHODS: To determine the minimum safe distance of a tubewell from a pit latrine in different hydrogeological conditions of Bangladesh, 20 monitoring wells were installed at three study sites (Manda, Mohanpur and Bagmara) with the vertical and horizontal distances ranging from 18-47 to 2-15 m, respectively. Water samples were collected three times in three seasons and tested for faecal coliforms (FC) and faecal streptococci (FS) as indicators of contamination. Soil samples were analysed for texture, bulk density and hydraulic conductivity following standard procedures. Sediment samples were collected to prepare lithological logs. RESULTS: When the shallow aquifers at one of the three sites (Mohanpur) were overlained by 18-23-m-thick aquitards, the groundwater of the monitoring wells was found contaminated with a lateral and vertical distances of 2 and 31 m, respectively. However, where the aquitard was only 9 m thick, contamination was found up to lateral and vertical distances of 4.5 and 40.5 m, respectively. The soil textures of all the sites were mainly composed of loam and sandy loam. The hydraulic conductivities in the first aquifer at Manda, Mohanpur and Bagmara were 5.2-7.3, 8.2 and 1.4-15.7 m/h, respectively. CONCLUSIONS: The results showed that the safe distance from the tubewell to the pit latrine varied from site to site depending on the horizontal and vertical distances of the tubewell as well as hydrogeological conditions of a particular area.

Microbiological Contamination of Drinking Water Associated with Subsequent Child Diarrhea.

We used a prospective, longitudinal cohort enrolled as part of a program evaluation to assess the relationship between drinking water microbiological quality and child diarrhea. We included 50 villages across rural Bangladesh. Within each village field-workers enrolled a systematic random sample of 10 households with a child under the age of 3 years. Community monitors visited households monthly and recorded whether children under the age of 5 years had diarrhea in the preceding 2 days. Every 3 months, a research assistant visited the household and requested a water sample from the source or container used to provide drinking water to the child. Laboratory technicians measured the concentration of Escherichia coli in the water samples using membrane filtration. Of drinking water samples, 59% (2,273/3,833) were contaminated with E. coli. Of 12,192 monthly follow-up visits over 2 years, mothers reported that their child had diarrhea in the preceding 2 days in 1,156 (9.5%) visits. In a multivariable general linear model, the log10 of E. coli contamination of the preceding drinking water sample was associated with an increased prevalence of child diarrhea (prevalence ratio = 1.14, 95% CI = 1.05, 1.23). These data provide further evidence of the health benefits of improved microbiological quality of drinking water.

Role of phytoplankton in maintaining endemicity and seasonality of cholera in Bangladesh.

BACKGROUND: In Bangladesh, cholera is endemic and maintains a regular seasonal pattern. The role of phytoplankton in maintaining endemicity and seasonality of cholera was monitored in Matlab, Bangladesh. METHODS: Phytoplankton and water samples were collected from two ponds bi-weekly for 1 year. The association of Vibrio cholerae O1 with phytoplankton was studied by culture and direct fluorescent antibody techniques. The bio-physicochemical parameters of water were measured and data for cases of cholera were collected from the records of Matlab hospital. The correlation of cholera cases with levels of phytoplankton, V. cholerae and bio-physicochemical parameters of water was carried out using Pearson's correlation coefficients. RESULTS: V. cholerae O1 survived for 48 days in association with Anabaena variabilis in a culturable state, but survived for a year in a viable but non-culturable (VBNC) state. V. cholerae survived for 12 and 32 days in a culturable state in control water (without algae) and water with algae, respectively. There was a significant correlation between changing levels of cholera cases in the community and the blue green algae and total phytoplankton in the aquatic environment. A significant correlation was also found between the cholera cases and chlorophyll-a and VBNC V. cholerae O1 in the aquatic environment. CONCLUSIONS: This study demonstrated the role of phytoplankton in maintaining endemicity and seasonality of cholera in Bangladesh.

Disgust sensitivity is not associated with health in a rural Bangladeshi sample.

Disgust can be considered a psychological arm of the immune system that acts to prevent exposure to infectious agents. High disgust sensitivity is associated with greater behavioral avoidance of disease vectors and thus may reduce infection risk. A cross-sectional survey in rural Bangladesh provided no strong support for this hypothesis. In many species, the expression of pathogen- and predator-avoidance mechanisms is contingent on early life exposure to predators and pathogens. Using childhood health data collected in the 1990s, we examined if adults with more infectious diseases in childhood showed greater adult disgust sensitivity: no support for this association was found. Explanations for these null finding and possible directions for future research are discussed.

Microbiological evaluation of the efficacy of soapy water to clean hands: a randomized, non-inferiority field trial.

We conducted a randomized, non-inferiority field trial in urban Dhaka, Bangladesh among mothers to compare microbial efficacy of soapy water (30 g powdered detergent in 1.5 L water) with bar soap and water alone. Fieldworkers collected hand rinse samples before and after the following washing regimens: scrubbing with soapy water for 15 and 30 seconds; scrubbing with bar soap for 15 and 30 seconds; and scrubbing with water alone for 15 seconds. Soapy water and bar soap removed thermotolerant coliforms similarly after washing for 15 seconds (mean log10 reduction = 0.7 colony-forming units [CFU], P < 0.001 for soapy water; mean log10 reduction = 0.6 CFU, P = 0.001 for bar soap). Increasing scrubbing time to 30 seconds did not improve removal (P > 0.05). Scrubbing hands with water alone also reduced thermotolerant coliforms (mean log10 reduction = 0.3 CFU, P = 0.046) but was less efficacious than scrubbing hands with soapy water. Soapy water is an inexpensive and microbiologically effective cleansing agent to improve handwashing among households with vulnerable children.

Cholera epidemic associated with consumption of unsafe drinking water and street-vended water--Eastern Freetown, Sierra Leone, 2012.

During 2012, Sierra Leone experienced a cholera epidemic with 22,815 reported cases and 296 deaths. We conducted a matched case-control study to assess risk factors, enrolling 49 cases and 98 controls. Stool specimens were analyzed by culture, polymerase chain reaction (PCR), and pulsed-field gel electrophoresis (PFGE). Conditional logistic regression found that consuming unsafe water (matched odds ratio [mOR]: 3.4; 95% confidence interval [CI]: 1.1, 11.0), street-vended water (mOR: 9.4; 95% CI: 2.0, 43.7), and crab (mOR: 3.3; 95% CI: 1.03, 10.6) were significant risk factors for cholera infection. Of 30 stool specimens, 13 (43%) showed PCR evidence of toxigenic Vibrio cholerae O1. Six specimens yielded isolates of V. cholerae O1, El Tor; PFGE identified a pattern previously observed in seven countries. We recommended ensuring the quality of improved water sources, promoting household chlorination, and educating street vendors on water handling practices.

High spatiotemporal resolution measurement of regional lung air volumes from 2D phase contrast x-ray images.

PURPOSE: Described herein is a new technique for measuring regional lung air volumes from two-dimensional propagation-based phase contrast x-ray (PBI) images at very high spatial and temporal resolution. Phase contrast dramatically increases lung visibility and the outlined volumetric reconstruction technique quantifies dynamic changes in respiratory function. These methods can be used for assessing pulmonary disease and injury and for optimizing mechanical ventilation techniques for preterm infants using animal models. METHODS: The volumetric reconstruction combines the algorithms of temporal subtraction and single image phase retrieval (SIPR) to isolate the image of the lungs from the thoracic cage in order to measure regional lung air volumes. The SIPR algorithm was used to recover the change in projected thickness of the lungs on a pixel-by-pixel basis (pixel dimensions ≈ 16.2 µm). The technique has been validated using numerical simulation and compared results of measuring regional lung air volumes with and without the use of temporal subtraction for removing the thoracic cage. To test this approach, a series of PBI images of newborn rabbit pups mechanically ventilated at different frequencies was employed. RESULTS: Regional lung air volumes measured from PBI images of newborn rabbit pups showed on average an improvement of at least 20% in 16% of pixels within the lungs in comparison to that measured without the use of temporal subtraction. The majority of pixels that showed an improvement was found to be in regions occupied by bone. Applying the volumetric technique to sequences of PBI images of newborn rabbit pups, it is shown that lung aeration at birth can be highly heterogeneous. CONCLUSIONS: This paper presents an image segmentation technique based on temporal subtraction that has successfully been used to isolate the lungs from PBI chest images, allowing the change in lung air volume to be measured over regions as small as the pixel size. Using this technique, it is possible to measure changes in regional lung volume at high spatial and temporal resolution during breathing at much lower x-ray dose than would be required using computed tomography.

Outbreak of mass sociogenic illness in a school feeding program in northwest Bangladesh, 2010.

BACKGROUND: In 2010, an acute illness outbreak was reported in school students eating high-energy biscuits supplied by the school feeding programme in northwest Bangladesh. We investigated this outbreak to describe the illness in terms of person, place and time, develop the timeline of events, and determine the cause and community perceptions regarding the outbreak. METHODS: We defined case-patients as students from affected schools reporting any two symptoms including abdominal pain, heartburn, bitter taste, and headache after eating biscuits on the day of illness. We conducted in-depth interviews and group discussions with students, teachers, parents and community members to explore symptoms, exposures, and community perceptions. We conducted a questionnaire survey among case-patients to determine the symptoms and ascertain food items eaten 12 hours before illness onset, and microbiological and environmental investigations. RESULTS: Among 142 students seeking hospital care, 44 students from four schools qualified as case-patients. Of these, we surveyed 30 who had a mean age of 9 years; 70% (21/30) were females. Predominant symptoms included abdominal pain (93%), heartburn (90%), and bitter taste (57%). All students recovered within a few hours. No pathogenic Vibrio cholerae, Shigella or Salmonella spp. were isolated from collected stool samples. We found no rancid biscuits in schools and storage sites. The female index case perceived the unusually darker packet label as a "devil's deed" that made the biscuits poisonous. Many students, parents and community members reported concerns about rumors of students dying from biscuit poisoning. CONCLUSIONS: Rapid onset, followed by rapid recovery of symptoms; female preponderance; inconsistent physical, microbiological and environmental findings suggested mass sociogenic illness rather than a foodborne or toxic cause. Rumours of student deaths heightening community anxiety apparently propagated this outbreak. Sharing investigation results and reassuring students and parents through health communication campaigns could limit similar future outbreaks and help retain beneficiaries' trust on nutrition supplementation initiatives.

What point-of-use water treatment products do consumers use? Evidence from a randomized controlled trial among the urban poor in Bangladesh.

BACKGROUND: There is evidence that household point-of-use (POU) water treatment products can reduce the enormous burden of water-borne illness. Nevertheless, adoption among the global poor is very low, and little evidence exists on why. METHODS: We gave 600 households in poor communities in Dhaka, Bangladesh randomly-ordered two-month free trials of four water treatment products: dilute liquid chlorine (sodium hypochlorite solution, marketed locally as Water Guard), sodium dichloroisocyanurate tablets (branded as Aquatabs), a combined flocculant-disinfectant powdered mixture (the PUR Purifier of Water), and a silver-coated ceramic siphon filter. Consumers also received education on the dangers of untreated drinking water. We measured which products consumers used with self-reports, observation (for the filter), and chlorine tests (for the other products). We also measured drinking water's contamination with E. coli (compared to 200 control households). FINDINGS: Households reported highest usage of the filter, although no product had even 30% usage. E. coli concentrations in stored drinking water were generally lowest when households had Water Guard. Households that self-reported product usage had large reductions in E. coli concentrations with any product as compared to controls. CONCLUSION: Traditional arguments for the low adoption of POU products focus on affordability, consumers' lack of information about germs and the dangers of unsafe water, and specific products not meshing with a household's preferences. In this study we provided free trials, repeated informational messages explaining the dangers of untreated water, and a variety of product designs. The low usage of all products despite such efforts makes clear that important barriers exist beyond cost, information, and variation among these four product designs. Without a better understanding of the choices and aspirations of the target end-users, household-based water treatment is unlikely to reduce morbidity and mortality substantially in urban Bangladesh and similar populations.