Not just a drop in the bucket: expanding access to point-of-use water treatment systems

Adoption of Point-of-Use Chlorination for Household Drinking Water Treatment: A Systematic Review

BACKGROUND

Centralized chlorination of urban piped water supplies has historically contributed to major reductions in waterborne illness. In locations without effective centralized water treatment, point-of-use (POU) chlorination for households is widely promoted to improve drinking water quality and health. Realizing these health benefits requires correct, consistent, and sustained product use, but real-world evaluations have often observed low levels of use. To our knowledge, no prior reviews exist on adoption of chlorine POU products.

OBJECTIVES

Our objectives were to identify which indicators of adoption are most often used in chlorine POU studies, summarize levels of adoption observed, understand how adoption changes over time, and determine how adoption is affected by frequency of contact between participants and study staff.

METHODS

We conducted a systematic review of household POU chlorination interventions or programs from 1990 through 2021 that reported a quantitative measure of adoption, were conducted in low- and middle-income countries, included data collection at households, and reported the intervention start date.

RESULTS

We identified 36 studies of household drinking water chlorination products that met prespecified eligibility criteria and extracted data from 46 chlorine intervention groups with a variety of chlorine POU products and locations. There was no consensus definition of adoption of household water treatment; the most common indicator was the proportion of household stored water samples with free chlorine residual > 0.1  or   0.2 mg / L . Among studies that reported either free or total chlorine-confirmed adoption of chlorine POU products, use was highly variable (across all chlorine intervention groups at the last time point measured in each study; range: 1.5%-100%; sample size-weighted median = 47 % ; unweighted median = 58 % ). The median follow-up duration among intervention groups was 3 months. On average, adoption declined over time and was positively associated with frequency of contact between respondents and study staff.

DISCUSSION

Although prior research has shown that POU chlorine products improve health when correctly and consistently used, a reliance on individual adoption for effective treatment is unlikely to lead to the widespread public health benefits historically associated with pressurized, centralized treatment of piped water supplies. https://doi.org/10.1289/EHP10839.

Evaluation of System-Level, Passive Chlorination in Gravity-Fed Piped Water Systems in Rural Nepal

Over 2 billion people globally lack access to safely managed drinking water. In contrast to the household-level, manually implemented treatment products that have been the dominant strategy for gaining low-cost access to safe drinking water, passive chlorination technologies have the potential to treat water and reduce reliance on individual behavior change. However, few studies exist that evaluate the performance and costs of these technologies over time, especially in small, rural systems. We conducted a nonrandomized evaluation of two passive chlorination technologies for system-level water treatment in six gravity-fed, piped water systems in small communities in the hilly region of western Nepal. We monitored water quality indicators upstream of the treatment, at shared taps, and at households, as well as user acceptability and maintenance costs, over 1 year. At baseline, over 80% of tap samples were contaminated with Escherichia coli. After 1 year of system-level chlorination, only 7% of those same taps had E. coli. However, 29% of household stored water was positive for E. coli. Per cubic meter of treated water, the cost of chlorine was 0.06-0.09 USD, similar to the cost of monitoring technology installations. Safe storage, service delivery models, and reliable supply chains are required, but passive chlorination technologies have the potential to radically improve how rural households gain access to safely managed water.

Electrochemical detection of selected heavy metals in water: a case study of African experiences

The safety of water resources throughout the globe has been compromised by various human activities and climate change over the last decades. Consequently, the world is currently confronted with a severe shortage of water supply and a water safety crisis, amidst a growing population. With poor environmental regulations, indiscriminate budding of urban slums, poverty, and a lack of basic knowledge of hygiene and sanitation, the African water supply has been critically threatened by different organic and inorganic contaminants, which results in several health issues. Inorganic pollutants such as heavy metals are particularly of interest because they are mostly stable and non-biodegradable. Therefore, they are not easily removed from water. In different parts of the continent, the concentration of heavy metals in drinking water far exceeds the permissible level recommended by the World Health Organization (WHO). Worse still, this problem is expected to increase with growing population, industrialization, urbanization, and, of course, corruption of government and local officials. Most of the African population is ignorant of the standards of safe water. In addition, the populace lack access to affordable and reliable technologies and tools that could be used in the quantification of these pollutants. This problem is not only applicable to domestic, but also to commercial, communal, and industrial water sources. Hence, a global campaign has been launched to ensure constant assessment of the presence of these metals in the environment and to promote awareness of dangers associated with unsafe exposure to them. Various conventional spectroscopic heavy metal detection techniques have been used with great success across the world. However, such techniques suffer from some obvious setbacks, such as the cost of procurement and professionalism required to operate them, which have limited their applications. This paper, therefore, reviews the condition of African water sources, health implications of exposure to heavy metals, and the approaches explored by various indigenous electrochemists, to provide a fast, affordable, sensitive, selective, and stable electrochemical sensors for the quantification of the most significant heavy metals in our water bodies.

Water, sanitation and hygiene (WASH) behaviour change research: why an analysis of contingencies of reinforcement is needed

Diarrheal disease associated with poor water, sanitation and hygiene (WASH) kills more than one million people every year. Safe WASH practices have the potential to greatly reduce these statistics but behaviour change interventions in the field have yielded little success to date. Currently, there is an emphasis on addressing cognitive processes to bring about changes in behaviour. In this review, a case is made for the benefits of a contingency-based perspective, focusing on the contextual antecedents and consequences of behaviour. The role of contingencies of reinforcement, not explored in previous WASH literature, is discussed as an explanatory framework for designing behaviour change strategies. A proper use of contrived reinforcers is recommended to counterbalance the natural reinforcers of convenience associated with risk practices. Recognising the role of consequences in the acquisition and maintenance of behaviour is an important step in the search for the answers urgently needed in the WASH field.

Water quality aspects related to domestic drinking water storage tanks and consideration in current standards and guidelines throughout the world - a review

In many parts of the world, drinking water storage takes place in near-house or in-house tanks. This can impact drinking water quality considerably. International and numerous national standards and guidelines addressing the construction, installation and operation of domestic drinking water storage tanks are reviewed on their consideration of water quality aspects and the minimisation of health risks associated with drinking water storage. Several national and international standards and guidelines are reviewed in terms of drinking water quality requirements. Factors that have an impact on water quality in relation to the use of domestic drinking water storage tanks are summarised comprehensively. The impact of the domestic storage of drinking water on water quality, the points and locations of use, their positioning, the materials they are made of, their design and operation, as well as aspects of how they are operated and maintained is outlined and discussed in detail. Finally, the incorporation of aspects regarding water quality in drinking water storage tanks in standards and guidelines is presented and assessed. To make the use of domestic drinking water storage tanks safer and more efficient, recommendations for modifications, improvements and extensions of respective standards are made.

Scaling Resistance in Nanophotonics-Enabled Solar Membrane Distillation

This study compares the scaling behavior of membrane distillation (MD) with that of nanophotonics-enabled solar membrane distillation (NESMD). Previous research has shown that NESMD, due to its localized surface heating driven by photothermal membrane coatings, is an energy-efficient system for off-grid desalination; however, concerns remained regarding the scaling behavior of self-heating surfaces. In this work, bench-scale experiments were performed, using model brackish water, to compare the scaling propensity of NESMD with MD. The results showed NESMD to be highly resistant to scaling; a three times higher salt concentration factor (c/c₀) was achieved in NESMD compared to MD without any decline in flux. Analyses of the scaling layer on NESMD membranes revealed that salt deposition was 1/4 of that observed for MD. Scaling resistance in NESMD is attributed to its lower operating temperature, which increases the solubility of common scalants and decreases salt precipitation rates. Precipitation kinetics measurements revealed an order of magnitude faster precipitation under heated conditions (62 °C, k = 8.7 × 10^-2 s^-1) compared to ambient temperature (22 °C, k = 7.1 × 10^-3 s^-1). These results demonstrate a distinct advantage of NESMD over MD for the treatment of high scaling potential water, where scaling is a barrier to high water recovery.

Application of tools to monitor environmental conditions, identify exposures, and inform decision-making to improve infection prevention and control practices in Malawian maternity wards

Healthcare-acquired infections (HAIs) contribute to maternal and neonatal morbidity and mortality, especially in low- and middle-income countries (LMICs). Deficient environmental health (EH) conditions and infection prevention and control (IPC) practices in healthcare facilities (HCFs) contribute to the spread of HAIs, but microbial sampling of sources of contamination is rarely conducted nor reported in low-resource settings. The purpose of this study was to assess EH conditions and IPC practices in Malawian HCFs and evaluate how EH deficiencies contribute to pathogen exposures and HAIs, and to provide recommendations to inform improvements in EH conditions using a mixed-methods approach. Thirty-one maternity wards in government-run HCFs were surveyed in the three regions of Malawi. Questionnaires were administered in parallel with structured observations of EH conditions and IPC practices and microbial testing of water sources and facility surfaces. Results indicated significant associations between IPC practices and microbial contamination. Facilities where separate wards were not available for mothers and newborns with infections and where linens were not used for patients during healthcare services were more likely to have delivery tables with surface contamination (relative risk = 2.23; 1.49, 3.34). E. coli was detected in water samples from seven (23%) HCFs. Our results suggest that Malawian maternity wards could reduce microbial contamination, and potentially reduce the occurrence of HAIs, by improving EH conditions and IPC practices. HCF staff can use the simple, low-cost EH monitoring methods used in this study to incorporate microbial monitoring of EH conditions and IPC practices in HCFs in low-resource settings.

Linking Decision Theory and Quantitative Microbial Risk Assessment: Tradeoffs Between Compliance and Efficacy for Waterborne Disease Interventions

Achieving health gains from the U.N. Sustainable Development Goals of universal coverage for water and sanitation will require interventions that can be widely adopted and maintained. Effectiveness-how an intervention performs based on actual use-as opposed to efficacy will therefore be central to evaluations of new and existing interventions. Incomplete compliance-when people do not always use the intervention and are therefore exposed to contamination-is thought to be responsible for the lower-than-expected risk reductions observed from water, sanitation, and hygiene interventions based on their efficacy at removing pathogens. We explicitly incorporated decision theory into a quantitative microbial risk assessment model. Specifically, we assume that the usability of household water treatment (HWT) devices (filters and chlorine) decreases as they become more efficacious due to issues such as taste or flow rates. Simulations were run to examine the tradeoff between device efficacy and usability. For most situations, HWT interventions that trade lower efficacy (i.e., remove less pathogens) for higher compliance (i.e., better usability) contribute substantial reductions in diarrheal disease risk compared to devices meeting current World Health Organization efficacy guidelines. Recommendations that take into account both the behavioral and microbiological properties of treatment devices are likely to be more effective at reducing the burden of diarrheal disease than current standards that only consider efficacy.

Nanomaterial-Supported Enzymes for Water Purification and Monitoring in Point-of-Use Water Supply Systems

Increasing pollution of global water sources and challenges in rapid detection and treatment of the wide range of contaminants pose considerable burdens on public health. The issue is particularly critical in rural areas, where building of centralized water treatment systems and pipe infrastructure to connect dispersed populations is not always practical. Point-of-use (POU) water supply systems provide cost-effective and energy-efficient approaches to store, treat, and monitor the quality of water. Currently available POU systems have limited success in dealing with the portfolio of emerging contaminants, particularly those present at trace concentrations. A site-to-site variation in contaminant species and concentrations also requires versatile POU systems to detect and treat contaminants and provide on-demand clean water. Among different technologies for developing rapid and sensitive water purification processes and sensors, enzymes offer one of the potential solutions because of their strong activity and selectivity toward chemical substrates. Many enzyme-nanomaterial composites have recently been developed that enhance enzymes' stability and activity and expand their functionality, thus facilitating the application of nanosupported enzymes in advanced POU systems. In this Account, we highlight the strengths and limitations of nanosupported enzymes for their potential applications in POU systems for water treatment as well as detection of contaminants, even at trace levels. We first summarize the mechanisms by which silica, carbon, and metallic nanosupports improve enzyme stability, selectivity, and catalysis. The unique immobilization properties and potential advantages of novel bioderived nanosupports over non-bioderived nanomaterials are emphasized. We illustrate prospective applications of nanosupported enzymes in POU systems with different roles: water purification, disinfection, and contaminant sensing. For each type of application, nanosupported enzymes offer higher performance than free enzymes. Nanosupports prolong enzymes' lifetimes and improve the rates of contaminant removal by concentrating contaminants near the enzymes. Nanosupports also stabilize antimicrobial enzymes while facilitating their attachment to bacterial surfaces, thereby increasing their potential uses for disinfection and prevention of biofouling in water purification and storage devices. As enzyme-based electrochemical sensors rely on electrochemical reactions of enzymatically generated species, the ability of conductive nanosupports to enhance enzyme activity and stability and to promote transfer of electrons onto the electrode greatly improves the sensitivity and durability of electroenzymatic contaminant sensors. Despite the promising results in laboratory settings, the application of nanosupported enzymes in real-world POU systems requires the implementation of multiple enzyme combinations and strategies for minimizing health risks associated with unintended releases of nanomaterials. Finally, we identify multidisciplinary research gaps in the development of nanosupported enzyme treatment systems and provide frameworks for the early adopters to make informed decisions on whether and how to use such POU systems.

Advancing performance evaluation standards for household water treatment technologies

Diarrheal illnesses and fatalities continue to be major issues in many regions throughout the world. Household water treatment (HWT) technologies (including both point-of-use (POU) and point-of-entry (POE) treatment solutions) have been shown as able to deliver safe water in many low-income communities. However, as shown herein, there are important inconsistencies in protocols employed for validating performance of HWTs. The WHO does not stipulate influent concentration as a parameter that could influence removal efficacy, nor does it indicate an influent concentration range that should be used during technology evaluations. A correlation between influent concentration and removal is evidenced herein (R² = 0.88) with higher influent concentrations resulting in higher log-removal values (LRVs). The absence of a recommended standard influent concentration of bacteria (as well as for viruses and protozoa) could have negative consequences in intervention efforts. Recommendations are provided that regulatory bodies should specify an influent concentration range for testing and verification of HWT technologies.

Perceptions of drinking water cleanliness and health-seeking behaviours: A qualitative assessment of household water safety in Lesotho, Africa

Despite the increased availability of improved water sources globally, enteric illnesses remain a source of significant morbidity and mortality. While the MDGs goal for safe water, i.e. improved sources, was met, substantial numbers of people still rely on unimproved sources for at least some of their water needs and contamination can occur between the source and consumption. Reviews and meta-analyses point to the need for better understanding of the cultural context for (HWT) technologies. Qualitative interviews (n = 56) conducted in the Maseru District of Lesotho (2011) addressed how people decided if their water was safe, their understanding of the linkage between water and enteric illness, and health-seeking behaviour. Respondents overwhelmingly relied on visual inspections to determine if their water was clean and not all participants linked consuming unsafe water with diarrheal disease. More than half of all respondents did not boil their water, despite believing that their primary source was not clean. People often have the knowledge necessary to ensure safe water but do not for myriad reasons, including financial constraints or habit. Data such as these are critical as the literature reveals often conflicting findings about the effectiveness of HWT and water safety takes on increasing importance in syndemic settings.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

High heterotrophic counts in potable water and antimicrobial resistance among indicator organisms in two peri-urban communities of Karachi, Pakistan

OBJECTIVE

Fecal contamination of potable water leads to unsafe water supply. Although many urban areas of large metropolitan cities receive safe water, peri-urban areas are often not monitored by public health authorities and water supply and quality remain unknown. We assessed microbiological quality and rates of antimicrobial resistance in viable indicator bacteria in two peri-urban communities of Karachi, Pakistan. Water samples were collected over 5 months (October 2015 to February 2016) from these peri-urban communities and samples were processed for microbiological quality as per Standing Committee of Analysts, United Kingdom and World Health Organization guidelines and criteria for drinking water.

RESULTS

Both communities received unimproved water. Potable water samples collected from 100 households showed that 96% of samples were unsafe for consumption. Extended spectrum beta lactamases production was found in 29.2% of fecal indicator organisms (coliforms). Use of unimproved water sources and unsafe potable water quality in peri-urban Karachi deserve immediate attention and upgrade. The study is instrumental in attracting the attention of authorities to the state of water resources in peri-urban communities in Karachi with a view to influence improvement of services and effects on human health.

Can you taste it? Taste detection and acceptability thresholds for chlorine residual in drinking water in Dhaka, Bangladesh

Chlorination is a low-cost, effective method for drinking water treatment, but aversion to the taste or smell of chlorinated water can limit use of chlorine treatment products. Forced choice triangle tests were used to evaluate chlorine detection and acceptability thresholds for two common types of chlorine among adults in Dhaka, Bangladesh, where previous studies have found low sustained uptake of chlorine water treatment products. The median detection threshold was 0.70mg/L (n=25, SD=0.57) for water dosed with liquid sodium hypochlorite (NaOCl) and 0.73mg/L (n=25, SD=0.83) for water dosed with solid sodium dichloroisocyanurate (NaDCC). Median acceptability thresholds (based on user report) were 1.16mg/L (SD=0.70) for NaOCl and 1.26mg/L (SD=0.67) for NaDCC. There was no significant difference in detection or acceptability thresholds for dosing with NaOCl versus NaDCC. Although users are willing to accept treated water in which they can detect the taste of chlorine, their acceptability limit is well below the 2.0mg/L that chlorine water treatment products are often designed to dose. For some settings, reducing dose may increase adoption of chlorinated water while still providing effective disinfection.

Contamination of Household Open Wells in an Urban Area of Trivandrum, Kerala State, India: A Spatial Analysis of Health Risk Using Geographic Information System

OBJECTIVE

To assess the sanitary condition and water quality of household wells and to depict it spatially using Geographic Information System (GIS) in an urban area of Trivandrum, Kerala state, India.

STUDY DESIGN

A community-based cross-sectional census-type study.

METHODS

Study was conducted in an urban area of Trivandrum. All households (n = 449) residing in a 1.05 km² area were enrolled in the study. Structured questionnaire and Differential Global Positioning System (DGPS) device were used for data collection. Water samples taken were analyzed in an accredited laboratory.

RESULTS

Most of the wells were in an intermediate-high contamination risk state, with more than 77% of wells having a septic tank within 7.5 m radius. Coliform contamination was prevalent in 73% of wells, and the groundwater was predominantly acidic with a mean of 5.4, rendering it unfit for drinking. The well chlorination and cleaning practices were inadequate, which were significantly associated with coliform contamination apart from a closely located septic tank. However, water purification practices like boiling were practiced widely in the area.

CONCLUSION

Despite the presence of wells with high risk of contamination and inadequate chlorination practices, the apparent rarity of Water-borne diseases in the area may be attributed to the widespread boiling and water purification practices at the consumption level by the households. GIS technology proves useful in picking environmental determinants like polluting sources near the well and to plan control activities.

Comparison of boiling and chlorination on the quality of stored drinking water and childhood diarrhoea in Indonesian households

We compared the impact of a commercial chlorination product (brand name Air RahMat) in stored drinking water to traditional boiling practices in Indonesia. We conducted a baseline survey of all households with children 1000 MPN/100 ml (RR 1·86, 95% CI 1·09-3·19) in stored water than in households without detectable E. coli. Although results suggested that Air RahMat water treatment was associated with lower E. coli contamination and diarrhoeal rates among children <5 years than water treatment by boiling, Air RahMat use remained low.

Factors Associated with the Duration of Moderate-to-Severe Diarrhea among Children in Rural Western Kenya Enrolled in the Global Enteric Multicenter Study, 2008-2012

Diarrheal disease is a leading cause of death among young children worldwide. As rates of acute diarrhea (AD; 1-6 days duration) have decreased, persistent diarrhea (PD; > 14 days duration) accounts for a greater proportion of the diarrheal disease burden. We describe factors associated with the duration of moderate-to-severe diarrhea in Kenyan children < 5 years old enrolled in the Global Enteric Multicenter Study. We found 587 (58%) children experienced AD, 360 (35%) had prolonged acute diarrhea (ProAD; 7-13 days duration), and 73 (7%) had PD. We constructed a Cox proportional hazards model to identify factors associated with diarrheal duration. Risk factors independently associated with longer diarrheal duration included infection with Cryptosporidium (hazard ratio [HR]: 0.868, P = 0.035), using an unimproved drinking water source (HR: 0.87, P = 0.035), and being stunted at enrollment (HR: 0.026, P < 0.0001). Diarrheal illness of extended duration appears to be multifactorial; given its association with adverse health and development outcomes, effective strategies should be implemented to reduce the duration and severity of diarrheal illness. Effective treatments for Cryptosporidium should be identified, interventions to improve drinking water are imperative, and nutrition should be improved through exclusive breastfeeding in infants ≤ 6 months and appropriate continued feeding practices for ill children.

The Limpopo Non-Metropolitan Drinking Water Supplier Response to a Diagnostic Tool for Technical Compliance

Water services providers should supply water that is fit for human consumption, taking into account multi-barrier approaches and technical aspects such as design aspects, operation monitoring, final water quality compliance monitoring, plant monitoring practices, maintenance, and risk management practices. Against this background, this study focused on applying the diagnostic tool for technical compliance as well as assessing the compliance of water treatment plants with management norms. Six plants in the Vhembe District Municipality were selected; the Vondo, Malamulele, Mutshedzi, and Mutale plants (conventional), and the Dzingahe and Tshedza package plants. During the first assessment, four (Malamulele, Mutshedzi, Mutale and Dzingahe) plants scored between 44% and 49% and achieved Class 3 certification, revealing serious challenges requiring immediate intervention. Two water plants (Vondo and Tshedza, scoring 53% and 63%, respectively) were in the Class 2 category, revealing serious challenges requiring attention and improvement. During the second assessment, all plants scored between 63% and 87% (Class 2 category). The greatest improvement (30%) was noted for the Dzingahe and Tshedza plants, followed by the Malamulele plant, while the Mutale, Vondo, and Mutshedzi plants improved their scores by 20%, 17% and 14%, respectively. After corrective actions and re-measurement, no plant complied. It is recommended that Water Services Providers (WSPs) regularly apply the diagnostic tools and water safety plans as developed in order to comply with applicable standards.

A prolonged, community-wide cholera outbreak associated with drinking water contaminated by sewage in Kasese District, western Uganda

BACKGROUND

In May 2015, a cholera outbreak that had lasted 3 months and infected over 100 people was reported in Kasese District, Uganda, where multiple cholera outbreaks had occurred previously. We conducted an investigation to identify the mode of transmission to guide control measures.

METHODS

We defined a suspected case as onset of acute watery diarrhoea from 1 February 2015 onwards in a Kasese resident. A confirmed case was a suspected case with Vibrio cholerae O1 El Tor, serotype Inaba cultured from a stool sample. We reviewed medical records to find cases. We conducted a case-control study to compare exposures among confirmed case-persons and asymptomatic controls, matched by village and age-group. We conducted environmental assessments. We tested water samples from the most affected area for total coliforms using the Most Probable Number (MPN) method.

RESULTS

We identified 183 suspected cases including 61 confirmed cases of Vibrio cholerae 01; serotype Inaba, with onset between February and July 2015. 2 case-persons died of cholera. The outbreak occurred in 80 villages and affected all age groups; the highest attack rate occurred in the 5-14 year age group (4.1/10,000). The outbreak started in Bwera Sub-County bordering the Democratic Republic of Congo and spread eastward through sustained community transmission. The first case-persons were involved in cross-border trading. The case-control study, which involved 49 confirmed cases and 201 controls, showed that 94% (46/49) of case-persons compared with 79% (160/201) of control-persons drank water without boiling or treatment (OR_M-H=4.8, 95% CI: 1.3-18). Water collected from the two main sources, i.e., public pipes (consumed by 39% of case-persons and 38% of control-persons) or streams (consumed by 29% of case-persons and 24% control-persons) had high coliform counts, a marker of faecal contamination. Environmental assessment revealed evidence of open defecation along the streams. No food items were significantly associated with illness.

CONCLUSIONS

This prolonged, community-wide cholera outbreak was associated with drinking water contaminated by faecal matter and cross-border trading. We recommended rigorous disposal of patients' faeces, chlorination of piped water, and boiling or treatment of drinking water. The outbreak stopped 6 weeks after these recommendations were implemented.

Employing CBPR to investigate function, utility, and longevity of household filters to improve potable water quality for indigenous peoples at Lake Atitlán, Guatemala: a pilot study with San Pedro de La Laguna

Cyanobacterial blooms at Lake Atitlán in Guatemala threaten and compromise the livelihood and health of local residents. Indigenous Tz'utujil, Kaqchikel, and K'iche' rely directly on lake water for drinking, bathing, cleaning, cooking, and fishing. Nonpoint source runoff and untreated wastewater pumped directly into the lake contribute to high fecal pathogen loads into source waters. Concurrent nutrient loading results in cyanobacterial blooms further compromising water quality. A lakeside municipality facing high rates of childhood gastrointestinal illness volunteered to engage in community-based participatory research (CBPR) to evaluate efficacy, utility, and longevity of filters in households. The filters consistently reduced the risk of coliforms and E. coli in household water drawn from the lake based on World Health Organization guidelines. Household surveys were simultaneously administered through a student leadership group regarding water usage, water quality, and community health. Filters demonstrated ability to reduce high loads of fecal indicators from source waters and ability to remove a cyanobacterial toxin (microcystin) at 10 μg/L in deionized water. Further studies are imperative to determine longevity of use in households and CBPR provides a powerful avenue to test efficacy of a possible intervention while engaging stakeholders and empowering community members with sustainable solutions.

Enteric pathogens and factors associated with acute bloody diarrhoea, Kenya

BACKGROUND

Shigellosis is the major cause of bloody diarrhoea worldwide and is endemic in most developing countries. In Kenya, bloody diarrhoea is reported weekly as part of priority diseases under Integrated Disease Surveillance and Response System (IDSR) in the Ministry of Health.

METHODS

We conducted a case control study with 805 participants (284 cases and 521 controls) between January and December 2012 in Kilifi and Nairobi Counties. Kilifi County is largely a rural population whereas Nairobi County is largely urban. A case was defined as a person of any age who presented to outpatient clinic with acute diarrhoea with visible blood in the stool in six selected health facilities in the two counties within the study period. A control was defined as a healthy person of similar age group and sex with the case and lived in the neighbourhood of the case.

RESULTS

The main presenting clinical features for bloody diarrhoea cases were; abdominal pain (69 %), mucous in stool (61 %), abdominal discomfort (54 %) and anorexia (50 %). Pathogen isolation rate was 40.5 % with bacterial and protozoal pathogens accounting for 28.2 % and 12.3 % respectively. Shigella was the most prevalent bacterial pathogen isolated in 23.6 % of the cases while Entamoeba histolytica was the most prevalent protozoal pathogen isolated in 10.2 % of the cases. On binary logistic regression, three variables were found to be independently and significantly associated with acute bloody diarrhoea at 5 % significance level; storage of drinking water separate from water for other use (OR = 0.41, 95 % CI 0.20-0.87, p = 0.021), washing hands after last defecation (OR = 0.24, 95 % CI 0.08-.076, p = 0.015) and presence of coliforms in main source water (OR = 2.56, CI 1.21-5.4, p = 0.014). Rainfall and temperature had strong positive correlation with bloody diarrhoea.

CONCLUSION

The main etiologic agents for bloody diarrhoea were Shigella and E. histolytica. Good personal hygiene practices such as washing hands after defecation and storing drinking water separate from water for other use were found to be the key protective factors for the disease while presence of coliform in main water source was found to be a risk factor. Implementation of water, sanitation and hygiene (WASH) interventions is therefore key in prevention and control of bloody diarrhoea.

Neighborhood diversity of potentially pathogenic bacteria in drinking water from the city of Maroua, Cameroon

This study examined the spatial variation of potential gastrointestinal pathogens within drinking water sources and home storage containers in four neighborhoods in Maroua, Cameroon. Samples were collected from source (n = 28) and home containers (n = 60) in each study neighborhood. Pathogen contamination was assessed using quantitative polymerase chain reaction, targeting Campylobacter spp., Shiga toxin producing Escherichia coli (virulence genes, stx1 and stx2), and Salmonella spp. Microbial source tracking (MST) targeted three different host-specific markers: HF183 (human), Rum2Bac (ruminant) and GFD (poultry) to identify contamination sources. Staphylococcus aureus and the tetracycline-resistance gene (tetQ) were assessed to measure human hand contact and presence of antibiotic-resistant bacteria. Pathogen/MST levels were compared statistically and spatially, and neighborhood variation was compared with previously collected demographic information. All the test fecal markers and pathogens (except Arcobacter) were detected in home and source samples. Two neighborhoods tested positive for most pathogens/MST while the others only tested positive for one or two. Spatial variation of pathogens/MST existed between sources, storage containers, and neighborhoods. Differing population density and ethno-economic characteristics could potentially explain variation. Future research should explore the influence of demographic and ethno-economic factors on water quality during microbial risk assessments in urban Africa.

Household Water Treatment and Safe Storage to Prevent Diarrheal Disease in Developing Countries

Household water treatment and safe storage (HWTS), such as boiling, filtering, or chlorinating water at home, have been shown to be effective in improving the microbiological quality of drinking water. However, estimates of their protective effect against diarrhea, a major killer, have varied widely. While results may be exaggerated because of reporting bias, this heterogeneity is consistent with other environmental interventions that are implemented with varying levels of coverage and uptake in settings where the source of exposure represents one of many transmission pathways. Evidence suggests that the effectiveness of HWTS can be optimized by ensuring that the method is microbiologically effective; (2) making it accessible to an exposed population; and (3) securing their consistent and long-term use.

Association of Supply Type with Fecal Contamination of Source Water and Household Stored Drinking Water in Developing Countries: A Bivariate Meta-analysis

BACKGROUND

Access to safe drinking water is essential for health. Monitoring access to drinking water focuses on water supply type at the source, but there is limited evidence on whether quality differences at the source persist in water stored in the household.

OBJECTIVES

We assessed the extent of fecal contamination at the source and in household stored water (HSW) and explored the relationship between contamination at each sampling point and water supply type.

METHODS

We performed a bivariate random-effects meta-analysis of 45 studies, identified through a systematic review, that reported either the proportion of samples free of fecal indicator bacteria and/or individual sample bacteria counts for source and HSW, disaggregated by supply type.

RESULTS

Water quality deteriorated substantially between source and stored water. The mean percentage of contaminated samples (noncompliance) at the source was 46% (95% CI: 33, 60%), whereas mean noncompliance in HSW was 75% (95% CI: 64, 84%). Water supply type was significantly associated with noncompliance at the source (p < 0.001) and in HSW (p = 0.03). Source water (OR = 0.2; 95% CI: 0.1, 0.5) and HSW (OR = 0.3; 95% CI: 0.2, 0.8) from piped supplies had significantly lower odds of contamination compared with non-piped water, potentially due to residual chlorine.

CONCLUSIONS

Piped water is less likely to be contaminated compared with other water supply types at both the source and in HSW. A focus on upgrading water services to piped supplies may help improve safety, including for those drinking stored water.

Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

Water is a life-giving source, fundamental to human existence, yet over a billion people lack access to clean drinking water. The present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively.

Evidence on the Effectiveness of Water, Sanitation, and Hygiene (WASH) Interventions on Health Outcomes in Humanitarian Crises: A Systematic Review

Background

Water, sanitation, and hygiene (WASH) interventions are amongst the most crucial in humanitarian crises, although the impact of the different WASH interventions on health outcomes remains unclear.

Aim

To examine the quantity and quality of evidence on WASH interventions on health outcomes in humanitarian crises, as well as evaluate current evidence on their effectiveness against health outcomes in these contexts.

Methods

A systematic literature review was conducted of primary and grey quantitative literature on WASH interventions measured against health outcomes in humanitarian crises occurring from 1980–2014. Populations of interest were those in resident in humanitarian settings, with a focus on acute crisis and early recovery stages of humanitarian crises in low and middle-income countries. Interventions of interest were WASH-related, while outcomes of interest were health-related. Study quality was assessed via STROBE/CONSORT criteria. Results were analyzed descriptively, and PRISMA reporting was followed.

Results

Of 3963 studies initially retrieved, only 6 published studies measured a statistically significant change in health outcome as a result of a WASH intervention. All 6 studies employed point-of-use (POU) water quality interventions, with 50% using safe water storage (SWS) and 35% using household water treatment (HWT). All 6 studies used self-reported diarrhea outcomes, 2 studies also reported laboratory confirmed outcomes, and 2 studies reported health treatment outcomes (e.g. clinical admissions). 1 study measured WASH intervention success in relation to both health and water quality outcomes; 1 study recorded uptake (use of soap) as well as health outcomes. 2 studies were unblinded randomized-controlled trials, while 4 were uncontrolled longitudinal studies. 2 studies were graded as providing high quality evidence; 3 studies provided moderate and 1 study low quality evidence.

Conclusion

The current evidence base on the impact of WASH interventions on health outcomes in humanitarian crises is extremely limited, and numerous methodological limitations limit the ability to determine associative, let alone causal, relationships.

Muddying the waters: a new area of concern for drinking water contamination in Cameroon

In urban Maroua, Cameroon, improved drinking water sources are available to a large majority of the population, yet this water is frequently distributed through informal distribution systems and stored in home containers (canaries), leaving it vulnerable to contamination. We assessed where contamination occurs within the distribution system, determined potential sources of environmental contamination, and investigated potential pathogens. Gastrointestinal health status (785 individuals) was collected via health surveys. Drinking water samples were collected from drinking water sources and canaries. Escherichia coli and total coliform levels were evaluated and molecular detection was performed to measure human-associated faecal marker, HF183; tetracycline-resistance gene, tetQ; Campylobacter spp.; and Staphylococcus aureus. Statistical analyses were performed to evaluate the relationship between microbial contamination and gastrointestinal illness. Canari samples had higher levels of contamination than source samples. HF183 and tetQ were detected in home and source samples. An inverse relationship was found between tetQ and E. coli. Presence of tetQ with lower E. coli levels increased the odds of reported diarrhoeal illness than E. coli levels alone. Further work is warranted to better assess the relationship between antimicrobial-resistant bacteria and other pathogens in micro-ecosystems within canaries and this relationship’s impact on drinking water quality.

Perceptional and socio-demographic factors associated with household drinking water management strategies in rural Puerto Rico

Identifying which factors influence household water management can help policy makers target interventions to improve drinking water quality for communities that may not receive adequate water quality at the tap. We assessed which perceptional and socio-demographic factors are associated with household drinking water management strategies in rural Puerto Rico. Specifically, we examined which factors were associated with household decisions to boil or filter tap water before drinking, or to obtain drinking water from multiple sources. We find that households differ in their management strategies depending on the institution that distributes water (i.e. government PRASA vs community-managed non-PRASA), perceptions of institutional efficacy, and perceptions of water quality. Specifically, households in PRASA communities are more likely to boil and filter their tap water due to perceptions of low water quality. Households in non-PRASA communities are more likely to procure water from multiple sources due to perceptions of institutional inefficacy. Based on informal discussions with community members, we suggest that water quality may be improved if PRASA systems improve the taste and odor of tap water, possibly by allowing for dechlorination prior to distribution, and if non-PRASA systems reduce the turbidity of water at the tap, possibly by increasing the degree of chlorination and filtering prior to distribution. Future studies should examine objective water quality standards to identify whether current management strategies are effective at improving water quality prior to consumption.

Water filtration using plant xylem

Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees--a readily available, inexpensive, biodegradable, and disposable material--can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm(3) of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings.

Point-of-use water disinfection using UV light-emitting diodes to reduce bacterial contamination

The treatment process described in this research explores the impact of exposing water samples containing fecal coliforms to the radiation produced by single ultraviolet (UV) light-emitting diodes (LEDs) operating at 265 nm. UV LEDs are long lasting, compact in size and produce more efficient light output than traditional mercury-vapour bulbs, making them ideal for application in point-of-use disinfection systems, such as in remote areas. In this study, contaminated water samples containing either a pure culture of Escherichia coli or tertiary effluent from the City of Regina Wastewater Treatment Plant were used to study the application and efficiency of using UV LEDs for water disinfection. The results indicate that bacterial inactivation was achieved in a time-dependent manner, with 1- and 2.5-log E. coli reductions in water following 20 and 50 min of UV LED exposure, respectively. Ultraviolet radiation was less effective in reducing coliform bacteria in wastewater samples due to the elevated turbidity levels. Further work remains to be completed to optimize the application of UV LEDs for point-of-use disinfection systems; however, the results from this study support that bacterial inactivation using UV LEDs is possible, meriting further future technological development of the LEDs.

A stepped wedge, cluster-randomized trial of a household UV-disinfection and safe storage drinking water intervention in rural Baja California Sur, Mexico

In collaboration with a local non-profit organization, this study evaluated the expansion of a program that promoted and installed Mesita Azul, an ultraviolet-disinfection system designed to treat household drinking water in rural Mexico. We conducted a 15-month, cluster-randomized stepped wedge trial by randomizing the order in which 24 communities (444 households) received the intervention. We measured primary outcomes (water contamination and diarrhea) during seven household visits. The intervention increased the percentage of households with access to treated and safely stored drinking water (23–62%), and reduced the percentage of households with Escherichia coli contaminated drinking water (risk difference (RD): −19% [95% CI: −27%, −14%]). No significant reduction in diarrhea was observed (RD: −0.1% [95% CI: −1.1%, 0.9%]). We conclude that household water quality improvements measured in this study justify future promotion of the Mesita Azul, and that future studies to measure its health impact would be valuable if conducted in populations with higher diarrhea prevalence.

Solar water disinfection (SODIS) of Escherichia coli, Enterococcus spp., and MS2 coliphage: effects of additives and alternative container materials

The use of alternative container materials and added oxidants accelerated the inactivation of MS2 coliphage and Escherichia coli and Enterococcus spp. bacteria during solar water disinfection (SODIS) trials. Specifically, bottles made from polypropylene copolymer (PPCO), a partially UVB-transparent plastic, resulted in three-log inactivation of these organisms in approximately half the time required for disinfection in bottles made from PET, polycarbonate, or Tritan(®), which absorb most UVB light. Furthermore, the addition of 125 mg/L sodium percarbonate in combination with either citric acid or copper plus ascorbate tended to accelerate inactivation by factors of 1.4-19. Finally, it was observed that the inactivation of E. coli and enterococci derived from local wastewater was far slower than the inactivation of laboratory-cultured E. coli and Enterococcus spp., while the inactivation of MS2 was slowest of all. These results highlight the importance of UVB in SODIS under certain conditions, and also the greater sunlight resistance of some viruses and of bacteria of fecal origin, as compared to the laboratory-cultured bacteria commonly used to model their inactivation. Furthermore, this study illustrates promising new avenues for accelerating the inactivation of bacteria and viruses by solar disinfection.

Building on success--potential to improve coverage of multiple health interventions through integrated delivery with routine childhood vaccination

BACKGROUND

Integrating delivery of nonvaccine interventions with childhood vaccinations has been suggested as a mechanism to accelerate progress toward Millennium Development Goals.

METHODS

Demographic health surveys from 28 sub-Saharan African countries were analyzed to determine potential coverage with 5 nonvaccine interventions that could be delivered to children, mothers, and families during routine infant vaccinations. Potential coverage levels were calculated among households with children aged 12-23 months, based on existing coverage of interventions and vaccinations.

FINDINGS

Most (>60%) children in families that had not received nonvaccine interventions had been vaccinated. If nonvaccine interventions could be delivered with vaccinations, the median percentage of households owning a bed net could increase from 46% to 92% and those with improved or treated sources of water from 55% to 91%. The median percentage of children who had received vitamin A supplementation could increase from 66% to 90%. Mothers who have been tested for human immunodeficiency virus could increase from 16% to 86%.

CONCLUSIONS

In Africa, vaccination programs could provide a platform to substantially increase coverage of nonvaccine interventions. Studies are needed to investigate programmatic approaches to optimize the selection, adoption, and long-term utilization of these interventions and to assess the impact on vaccination and other intervention coverage.

Factors associated with high prevalence of intestinal protozoan infections among patients in Sana'a City, Yemen

BACKGROUND

Intestinal protozoan diseases in Yemen are a significant health problem with prevalence ranging from 18% to 27%. The present study is a cross-sectional study aimed at determining the factors associated with the high prevalence of intestinal protozoan infections among patients seeking health care in Sana'a City, the capital of Yemen.

METHODOLOGY/PRINCIPAL FINDINGS

Stool samples were collected from 503 patients aged between 1 and 80 years old; 219 were males and 284 females. Biodata were collected via pretested standard questionnaire. Faecal samples were processed and examined for (oo)cysts or ova using a wet mount preparation after formal-ether concentration technique. Cryptosporidium oocysts were detected using the Ziehl-Neelsen staining technique. The overall prevalence of intestinal protozoan infections was 30.9%. Infection rates of Giardia duodenalis, Entamoeba histolytica/dispar and Cryptosporidium were 17.7%, 17.1% and 1%, respectively. Other parasites detected included Ascaris lumbricoides (2.4%), Schistosoma mansoni (0.3%), Hymenolepis nana (1.4%) and Enterobius vermicularis (0.4%). Multivariate analysis using forward stepwise logistic regression based on intestinal protozoan infections showed that contact with animals (OR = 1.748, 95% CI = 1.168-2.617) and taking bath less than twice a week (OR = 1.820, 95% CI = 1.192-2.779) were significant risk factors of protozoan infections.

CONCLUSIONS/SIGNIFICANCE

This present study indicated that intestinal protozoan infections are still a public health problem in Yemen, with Giardia and Entamoeba infections being most common. Statistical analysis indicated that low personal hygiene and contact with animals were important predictors for intestinal protozoan infections. As highlighted in this study, in order to effectively reduce these infections, a multi-sectoral effort is needed. Preventive measures should include good hygienic practices, good animal husbandry practices, heightened provision of educational health programs, health services in all governorates including rural areas. Furthermore, it is also essential to find radical solutions to the recent water crises in Yemen.

A Survey of the Community Water Supply of some rural Riverine Communities in the Niger Delta region, Nigeria: Health implications and literature search for suitable interventions

BACKGROUND: Water is a fundamental human need. This is the basis for target 10, goal 7 of the Millennium Development Goals which sets to reduce the proportion of people without access to safe water by half by 2015. This study assessed the access to safe water supply in 22 riverine communities in the Niger delta region of Nigeria. MATERIALS AND METHOD: The study was carried out using a descriptive cross-sectional study design, with the data collected using a structured interviewer-administered questionnaire, field observations and focused group discussions. The questionnaire was administered to female heads of household, and used to collect information on the main source of drinking water, the time it took for the round trip to the main water sources, and methods used for the treatment of water of suspicious quality. An inventory of all the community water facilities in the communities was also taken, and information collected on the functionality of the facilities, and how they were constructed, operated and maintained. A sample of the water from each of the facilities was also collected in a sterile container for microbiological analysis. RESULTS: A total of 456 questionnaires were administered and retrieved. The most common source of drinking water was surface water (37.9%), and most (61.2%) of the water drawers spent less than 15 minutes to complete the round trip to the water sources. There were an average of 17 community water supply facilities, but only 23.8% of the facilities were functional during the study. Most of the functional facilities were being managed by community members. More than two third (67.9%) of the samples tested were found to contain significant numbers of Escherichia coli. CONCLUSION: The communities had easy access to water supply, but most of the facilities were either contaminated or nonfunctional. The management of the facilities by members of the communities, and the promotion of point-of-use purification systems are hereby advocated.

Determinants of use of household-level water chlorination products in rural Kenya, 2003-2005

Household-level water treatment products provide safe drinking water to at-risk populations, but relatively few people use them regularly; little is known about factors that influence uptake of this proven health intervention. We assessed uptake of these water treatments in Nyanza Province, Kenya, November 2003–February 2005. We interviewed users and non-user controls of a new household water treatment product regarding drinking water and socioeconomic factors. We calculated regional use-prevalence of these products based on 10 randomly selected villages in the Asembo region of Nyanza Province, Kenya. Thirty-eight percent of respondents reported ever using household-level treatment products. Initial use of a household-level product was associated with having turbid water as a source (adjusted odds ratio [AOR] = 16.6, p = 0.007), but consistent usage was more common for a less costly and more accessible product that did not address turbidity. A combination of social marketing, retail marketing, and donor subsidies may be necessary to extend the health benefits of household-level water treatment to populations most at risk.

Urban area disadvantage and under-5 mortality in Nigeria: the effect of rapid urbanization

BACKGROUND

Living in socioeconomically disadvantaged areas is associated with increased -childhood mortality risks. As city living becomes the predominant social context in low- and middle-income countries, the resulting rapid urbanization together with the poor economic circumstances of these countries greatly increases the risks of mortality for children < 5 years of age (under-5 mortality).

OBJECTIVE

In this study we examined the trends in urban population growth and urban under-5 mortality between 1983 and 2003 in Nigeria. We assessed whether urban area socioeconomic dis-advantage has an impact on under-5 mortality.

METHODS

Urban under-5 mortality rates were directly estimated from the 1990, 1999, and 2003 Nigeria Demographic and Health Surveys. Multilevel logistic regression analysis was performed on data for 2,118 children nested within data for 1,350 mothers, who were in turn nested within data for 165 communities.

RESULTS

Urban under-5 mortality increased as urban population steadily increased between 1983 and 2003. Urban area disadvantage was significantly associated with under-5 mortality after adjusting for individual child- and mother-level demographic and socioeconomic characteristics.

CONCLUSIONS

Significant relative risks of under-5 deaths at both individual and community levels underscore the need for interventions tailored toward community- and individual-level interventions. We stress the need for further studies on community-level determinants of under-5 mortality in disadvantaged urban areas.

A typhoid fever outbreak in a slum of South Dumdum municipality, West Bengal, India, 2007: evidence for foodborne and waterborne transmission

Background

In April 2007, a slum of South Dumdum municipality, West Bengal reported an increase in fever cases. We investigated to identify the agent, the source and to propose recommendations.

Methods

We defined a suspected case of typhoid fever as occurrence of fever for ≥ one week among residents of ward 1 of South Dumdum during February – May 2007. We searched for suspected cases in health care facilities and collected blood specimens. We described the outbreak by time, place and person. We compared probable cases (Widal positive >= 1:80) with neighbourhood-matched controls. We assessed the environment and collected water specimens.

Results

We identified 103 suspected cases (Attack rate: 74/10,000, highest among 5–14 years old group, no deaths). Salmonella (enterica) Typhi was isolated from one of four blood specimens and 65 of 103 sera were >= 1:80 Widal positive. The outbreak started on 13 February, peaked twice during the last week of March and second week of April and lasted till 27 April. Suspected cases clustered around three public taps. Among 65 probable cases and 65 controls, eating milk products from a sweet shop (Matched odds ratio [MOR]: 6.2, 95% confidence interval [CI]: 2.4–16, population attributable fraction [PAF]: 53%) and drinking piped water (MOR: 7.3, 95% CI: 2.5–21, PAF-52%) were associated with illness. The sweet shop food handler suffered from typhoid in January. The pipelines of intermittent non-chlorinated water supply ran next to an open drain connected with sewerage system and water specimens showed faecal contamination.

Conclusion

The investigation suggested that an initial foodborne outbreak of typhoid led to the contamination of the water supply resulting in a secondary, waterborne wave. We educated the food handler, repaired the pipelines and ensured chlorination of the water.

Risk factors for typhoid in Darjeeling, West Bengal, India: evidence for practical action

OBJECTIVE

To identify risk factors for typhoid and propose prevention measures.

METHODS

Case-control study; we compared hospital-based typhoid cases defined as fever>38 degrees C for >or=3 days with four-fold rise in 'O' antibodies on paired sera (Widal) with community, age and neighbourhood matched controls. We obtained information on drinking water, fruits, vegetables, milk products and sanitation; and calculated matched odds ratios (MOR) and attributable fractions in the population (AFP) for the risk factors or failure to use prevention measures.

RESULTS

The 123 typhoid cases (median age: 25 years, 47% female) and 123 controls did not differ with respect to baseline characteristics. Cases were less likely to store drinking water in narrow-mouthed containers (MOR: 0.4, 95% CI: 0.2-0.7, AFP 29%), tip containers to draw water (MOR: 0.4, 95% CI: 0.2-0.7, AFP 33%) and have home latrines (MOR: 0.5, 95% CI: 0.3-0.8, AFP 23%). Cases were more likely to consume butter (OR: 2.3, 95% CI: 1.3-4.1, AFP 28%), yoghurt (OR: 2.3, 95% CI: 1.4-3.7, AFP 34%) and raw fruits and vegetables, including onions (MOR: 2.1, 95% CI: 1.2-3.9, AFP 34%), cabbages (OR: 2.8, 95% CI: 1.7-4.8, AFP 44%) and unwashed guavas (OR: 1.9, 95% CI: 1.2-3, AFP 25%).

CONCLUSION

Typhoid was associated with unsafe water and sanitation practices as well as with consumption of milk products, fruits and vegetables. We propose to chlorinate drinking water at the point of use, wash/cook raw fruits and vegetables and ensure safer preparation/storage of local milk products.

Killing of enteric bacteria in drinking water by a copper device for use in the home: laboratory evidence

Water inoculated with 500-1000 colony forming units/ml of Escherichia coli, Salmonella Typhi and Vibrio cholerae was stored overnight at room temperature in copper pots or in glass bottles containing a copper coil devised by us. The organisms were no longer recoverable when cultured on conventional media, by contrast with water stored in control glass bottles under similar conditions. The amount of copper leached into the water after overnight storage in a copper pot or a glass bottle with a copper device was less than 475 parts per billion, which is well within the safety limits prescribed by the WHO. The device is inexpensive, reusable, easy to maintain, durable, does not need energy to run and appears to be safe. It has the potential to be used as a household water purification method for removing enteric bacteria, especially in developing countries.

Solar radiation disinfection of drinking water at temperate latitudes: inactivation rates for an optimised reactor configuration

Solar radiation-driven inactivation of bacteria, virus and protozoan pathogen models was quantified in simulated drinking water at a temperate latitude (34 degrees S). The water was seeded with Enterococcus faecalis, Clostridium sporogenes spores, and P22 bacteriophage, each at ca 1x10(5) mL(-1), and exposed to natural sunlight in 30-L reaction vessels. Water temperature ranged from 17 to 39 degrees C during the experiments lasting up to 6h. Dark controls showed little inactivation and so it was concluded that the inactivation observed was primarily driven by non-thermal processes. The optimised reactor design achieved S90 values (cumulative exposure required for 90% reduction) for the test microorganisms in the range 0.63-1.82 MJ m(-2) of Global Solar Exposure (GSX) without the need for TiO2 as a catalyst. High turbidity (840-920 NTU) only reduced the S(90) value by <40%. Further, when all S90 means were compared this decrease was not statistically significant (prob.>0.05). However, inactivation was significantly reduced for E. faecalis and P22 when the transmittance of UV wavelengths was attenuated by water with high colour (140 PtCo units) or a suboptimally transparent reactor lid (prob.<0.05). S90 values were consistent with those measured by other researchers (ca 1-10 MJ m(-2)) for a range of waters and microorganisms. Although temperatures required for SODIS type pasteurization were not produced, non-thermal inactivation alone appeared to offer a viable means for reliably disinfecting low colour source waters by greater than 4 orders of magnitude on sunny days at 34 degrees S latitude.

Decentralized systems for potable water and the potential of membrane technology

Decentralized drinking-water systems are an important element in the process of reaching the Millennium Development Goals, as centralized systems are often deficient or non-existent in developing and transition countries (DC and TC). Most water-quality problems are due to hygiene factors and pathogens. A range of decentralized systems is available to counter these problems, including thermal and/or UV methods, physical removal and chemical treatment. This review focuses on decentralized systems that treat the potable water (drinking and cooking) of a single household (point-of-use systems) or a community (small-scale systems). For application in DC and TC, important boundary conditions for decentralized systems include low costs, ease of use, sustainability, low maintenance and independence of utilities (energy sources). Although some low-cost systems are available, their application is limited by time-consuming daily operation and maintenance. Other systems are too expensive for the poor populations of DC and TC and in most cases do not fulfill the system requirements described above. Point-of-use systems based on membranes are commercially available and are designed to operate on tap pressure or gravity. Membrane systems are attractive since they provide an absolute barrier for pathogens and remove turbidity, thus increasing the palatability of the water. The costs of membrane have decreased rapidly during the last decades and therefore membrane systems have also become within reach for application in low-cost applications in DC and TC. Some membrane systems rely on gravity as a driving force, thereby avoiding the use of pumps and electricity. On the basis of the present literature data, no small-scale systems could be identified which meet all the requirements for successful implementation. Furthermore, in the available literature the performance of highly fouling water types has not been reported. For such cases, more extensive studies are required and a need for suitable pre-treatment was identified. It can be concluded that there are good prospects for decentralized systems based on membranes, but that a need exists for research and development of systems with low costs and low maintenance, specifically designed for DC and TC.

Following the water: a controlled study of drinking water storage in northern coastal Ecuador

BACKGROUND

To design the most appropriate interventions to improve water quality and supply, information is needed to assess water contamination in a variety of community settings, including those that rely primarily on unimproved surface sources of drinking water.

OBJECTIVES

We explored the role of initial source water conditions as well as household factors in determining household water quality, and how levels of contamination of drinking water change over time, in a rural setting in northern coastal Ecuador.

METHODS

We sampled source waters concurrently with water collection by household members and followed this water over time, comparing Escherichia coli and enterococci concentrations in water stored in households with water stored under controlled conditions.

RESULTS

We observed significant natural attenuation of indicator organisms in control containers and significant, although less pronounced, reductions of indicators between the source of drinking water and its point of use through the third day of sampling. These reductions were followed by recontamination in approximately half of the households.

CONCLUSIONS

Water quality improved after water was transferred from the source to household storage containers, but then declined because of recontamination in the home. Our experimental design allowed us to observe these dynamics by controlling for initial source water quality and following changes in water quality over time. These data, because of our controlled experimental design, may explain why recontamination has been reported in the literature as less prominent in areas or households with highly contaminated source waters. Our results also suggest that efforts to improve source water quality and sanitation remain important.

Bacterial quality of drinking water stored in containers by boat households in Hue City, Vietnam

OBJECTIVES

To examine the bacterial quality of drinking water stored in containers by boat households in the river basin of Hue City, and associated factors.

METHODS

Ready-to-drink water stored in containers on boats was collected from 766 households. Escherichia coli (E. coli), total coliforms, and Enterobacteriaceae in the water were examined by the rehydratable dry-film plating method. Socioeconomic characteristics, water source, handling practices, and proficiency of disease prevention of individual households were assessed.

RESULTS

E. coli, over ten counts of total coliforms, and over ten counts of Enterobacteriaceae were detected in 25.7, 44.5, and 51.5% of 1-ml samples of ready-to-drink water stored in containers on the boats. Bacterial contamination of the water stored in containers by boat households was significantly associated with use of river water as a source of drinking water, non-boiling before storing containers for drinking, and limited proficiency in disease prevention regardless of the influence of socioeconomic characteristics of the households (P < 0.01, P < 0.05, P < 0.01, respectively).

CONCLUSIONS

Bacterial contamination of ready-to-drink water stored by boat households was indicated. The households' proficiency in disease prevention buffered contamination. A comprehensive health promotion program with a wide range of contents is required for the communities of boat households.