Safe Water Sources Research Articles

PERFORMANCE EFFICIENCY ANALYSIS OF WATER TREATMENT PLANTS BY USING MCDM AND NEURAL NETWORK MODEL

The organization of safe and sustainable sources of water remains a priority for decision makers around the world. The centrality of water in public health as well as in industry creates a high demand for water supply of suitable quality that many nations around the world are harassed to meet. In India, in particular, water shortages and poor water quality continue to be major challenges in both domestic and industrial sectors. That is why, the evaluation of the performance efficiency of the existing water treatment plant is essential. This paper utilizes the Non-structural Fuzzy Decision Support System (NSFDSS) as well as Artificial Neural Network (ANN) to identify the parameter that is most significant in helping the decision makers to build an efficient water treatment plant operating system.

Water versus Wireless Coverage in Rural Mali: Links and Paradoxes

Water and wireless coverage were evaluated in a rural commune of southern Mali. All improved water sources in the area were checked for operability, accessibility, and water quality, while wireless coverage was tested by means of smartphones, phone calls, and instant messaging applications. Theoretical water coverage exceeded 82% of the total village surface area, thus beating the national and sub-Saharan African averages, but dropped to just 39% when considering only serviceable and contamination-free sources. In contrast, wireless coverage exceeded 90%. These outcomes highlight a triple paradox: (1) water from theoretically safe (i.e., improved) water sources is often unsafe to drink; (2) wireless access is better than water access even though water is essential for human survival and telecommunications are not; and (3) excellent Internet coverage does not help a large number of people, who lack the skills, devices, or need to access it. While telecommunications seem to be making inroads towards universal access faster than the water sector, a survey of water committees uncovered a hidden nexus between both resources, revealing that increased wireless access is actually contributing to underpin water coverage in a variety of ways.

Uptake of hazardous elements by spring onion (Allium fistulosum L.) from soil irrigated with different types of water and possible health risk

Bio-concentration of elements such as Mo, As, Se, Fe, Cu, Zn, Ni and Pb was analyzed in spring onion (Allium fistulosum L.) in three different locations of central Punjab, Pakistan. At location GW, relatively low level of hazardous elements was found in spring onion, suggesting that groundwater is a safe source of water for irrigating food crops. The pH of soil at wastewater irrigation was found less acidic (pH 7.4) than the other sites. The range of concentration in the different samples of spring onion was as follows: 6.15–8.16 mg kg−1 for Mo, 2.77–4.28 mg kg−1 for As, 0.395–0.705 mg kg−1 for Se, 36.73–48.17 mg kg−1 for Fe, 10.58–16.26 mg kg−1 for Cu, 28.87–39.79 mg kg−1 for Zn, 6.66–8.75 mg kg−1 for Ni and 4.33–6.09 mg kg−1 for Pb, respectively. High bio-concentration of Zn (15.37) from soil to spring onion was found at canal water irrigated location. The estimated daily intake of metal for spring onion was less, but the health risk index was higher than 1 for Mo, As, Cu, Pb and Ni, respectively. This was due to higher proportion of spring onion in diet, which consequently increased the health risk index for metals. Therefore, it is recommended to avoid growing vegetables in untreated urban and rural wastewater containing elevated amounts of metals.

Review: Epidemiological evidence of groundwater contribution to global enteric disease, 1948–2015

Globally, approximately 2.2 billion people rely on groundwater for daily consumption. It is widely accepted that groundwater is more pristine than surface water but while this assumption is frequently the case, groundwater is not ubiquitously free of contaminants; accordingly, this presumption can result in an unfounded and potentially hazardous sense of security among owners, operators and users. The current paper presents a review of published literature providing epidemiological evidence of the contribution of groundwater to global human enteric infection. An emphasis is placed on enteric pathogens transmitted via the faecal-oral route, and specifically those associated with acute gastrointestinal illness (AGI). The review identified 649 published groundwater outbreaks globally between 1948 and 2013 and several epidemiological studies that show there is an increased risk of AGI associated with the consumption of untreated groundwater. The review identified that the following five pathogens were responsible for most outbreaks: norovirus, Campylobacter, Shigella, Hepatitis A and Giardia. Crudely, the authors estimate that between 35.2 and 59.4 million cases of AGI per year globally could be attributable to the consumption of groundwater. Although groundwater is frequently presumed to be a microbiologically safe source of water for consumption, this review demonstrates that consumers served by an untreated groundwater supply remain at risk to enteric disease. The authors conclude that collaboration between microbiologists, hydrogeologists and epidemiologists is needed to better understand pathogen occurrence, persistence, detection and transport in groundwater as well as build stronger epidemiological evidence documenting the true magnitude of disease associated with groundwater globally.

English

Fecal contamination of drinking water is a major problem in rural communities of Ethiopia, where surface water sources like rivers, wells, and lakes are used for drinking. In spite of these problems, few data exist on the microbiological safety of water sources in these settings. Therefore, the aim of this study was to investigate the microbiological safety of drinking water from the sources and households in selected communities of Shashemane rural district, Ethiopia. A descriptive analytic study was used to examine the bacteriological quality of drinking water from sources and household containers. Data on water collection and storage practices were collected using structured questionnaires. Water samples were collected according to the WHO Guidelines for drinking water quality assessment from surface and ground water sources which are used directly for drinking purpose in the community. Water samples were examined for total coliforms and fecal coliforms using the most probable number methods. The detection of Escherichia coli, Salmonella, Shigella, and Vibrio cholerae were assessed by biochemical tests. Total coliforms were detected in higher proportion in all water source samples. Fecal coliform contamination was detected in all water sources, except in hand pipes. E. coli, Salmonella and Shigella species were detected in water samples from river and wells. Total coliforms, fecal coliforms, E. coli and Salmonella spp. were also detected in water samples from households. The bacteriological load of the sampled water from source and households was found to be higher than the maximum value set for drinking water. Therefore, enabling the community access to potable water through encouraging construction of toilets, creating proper domestic and animal waste disposal system and rendering health education and sanitation practices for the community is recommended. Key words: Diarrhea, drinking water, Ethiopia, fecal coliforms, Shashemane, total coliforms.

Can Sanitary Inspection Surveys Predict Risk of Microbiological Contamination of Groundwater Sources? Evidence from Shallow Tubewells in Rural Bangladesh.

Accurately assessing the microbiological safety of water sources is essential to reduce waterborne fecal exposures and track progress toward global targets of safe water access. Sanitary inspections are a recommended tool to assess water safety. We collected 1,684 water samples from 902 shallow tubewells in rural Bangladesh and conducted sanitary surveys to assess whether sanitary risk scores could predict water quality, as measured by Escherichia coli. We detected E. coli in 41% of tubewells, mostly at low concentrations. Based on sanitary scores, 31% of wells were low risk, 45% medium risk, and 25% high or very high risk. Older wells had higher risk scores. Escherichia coli levels were higher in wells where the platform was cracked or broken (Δlog10 = 0.09, 0.00-0.18) or undercut by erosion (Δlog10 = 0.13, 0.01-0.24). However, the positive predictive value of these risk factors for E. coli presence was low (< 50%). Latrine presence within 10 m was not associated with water quality during the wet season but was associated with less frequent E. coli detection during the dry season (relative risk = 0.72, 0.59-0.88). Sanitary scores were not associated with E. coli presence or concentration. These findings indicate that observed characteristics of a tubewell, as measured by sanitary inspections in their current form, do not sufficiently characterize microbiological water quality, as measured by E. coli. Assessments of local groundwater and geological conditions and improved water quality indicators may reveal more clear relationships. Our findings also suggest that the dominant contamination route for shallow groundwater sources is short-circuiting at the wellhead rather than subsurface transport.

A Multiscale Model for the World's First Parasitic Disease Targeted for Eradication: Guinea Worm Disease.

Guinea worm disease (GWD) is both a neglected tropical disease and an environmentally driven infectious disease. Environmentally driven infectious diseases remain one of the biggest health threats for human welfare in developing countries and the threat is increased by the looming danger of climate change. In this paper we present a multiscale model of GWD that integrates the within-host scale and the between-host scale. The model is used to concurrently examine the interactions between the three organisms that are implicated in natural cases of GWD transmission, the copepod vector, the human host, and the protozoan worm parasite (Dracunculus medinensis), and identify their epidemiological roles. The results of the study (through sensitivity analysis of R0) show that the most efficient elimination strategy for GWD at between-host scale is to give highest priority to copepod vector control by killing the copepods in drinking water (the intermediate host) by applying chemical treatments (e.g., temephos, an organophosphate). This strategy should be complemented by health education to ensure that greater numbers of individuals and communities adopt behavioural practices such as voluntary reporting of GWD cases, prevention of GWD patients from entering drinking water bodies, regular use of water from safe water sources, and, in the absence of such water sources, filtering or boiling water before drinking. Taking into account the fact that there is no drug or vaccine for GWD (interventions which operate at within-host scale), the results of our study show that the development of a drug that kills female worms at within-host scale would have the highest impact at this scale domain with possible population level benefits that include prevention of morbidity and prevention of transmission.

Analysis of Physical and Chemical Parameters in Ground Water Used for Drinking around Konso Area, Southwestern Ethiopia

To improve water quality, there should be a mechanism of keeping safe water source from chemical contaminants in an effective and protective way through the application of regular check up and with interventions by taking exact measure periodically before it is supplied for usage. The intention of this research work is to determine the level of common cations, anions, heavy metals and physical parameters in drinking water supply system in konso and its surrounding area, Southwestern of Ethiopia. Water samples were collected from 23 different locations in the area where there is hand pump or motorized supply system that are used for drinking purpose. Collected samples were analyzed for physicochemical parameters including total alkalinity, Temperature, pH, Electrical Conductivity, Total dissolved solids, Turbidity, Alkalinity, Total hardness and Total suspended solid. Common cations (Li+, K+, Na+,Ca2+ and Mg2+), Common anions (NO3−, SO42−, PO42−, F− and Cl−) and Heavy metals (Pd, Ni, Mn, Pb, Co, Zn, Cu) were analyzed. The obtained results were compared with some national and international standards or guidelines for drinking water. Accordingly, the results obtained show that most of the physical and some common ions and heavy metals were within the accepted range of the guideline recommended by WHO. In addition to this, some parameters are at alarming state as compared to the WHO standards for drinking purposes, thereby suggesting the need for treatment and precautionary measures for use of the particular ground water.

Hydrological Regime and Water Shortage as Drivers of the Seasonal Incidence of Diarrheal Diseases in a Tropical Montane Environment.

BackgroundThe global burden of diarrhea is a leading cause of morbidity and mortality worldwide. In montane areas of South-East Asia such as northern Laos, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads, and potential pathogen dissemination. To our knowledge, few studies have related diarrhea incidences to catchment scale hydrological factors such as river discharge, and loads of suspended sediment and of Fecal Indicator Bacteria (FIB) such as Escherichia coli, together with sociological factors such as hygiene practices. We hypothesized that climate factors combined with human behavior control diarrhea incidence, either because higher rainfall, leading to higher stream discharges, suspended sediment loads and FIB counts, are associated with higher numbers of reported diarrhea cases during the rainy season, or because water shortage leads to the use of less safe water sources during the dry season. Using E. coli as a FIB, the objectives of this study were thus (1) to characterize the epidemiological dynamics of diarrhea in Northern Laos, and (2) to identify which hydro-meteorological and sociological risk factors were associated with diarrhea epidemics.MethodsConsidering two unconnected river catchments of 22 and 7,448 km2, respectively, we conducted a retrospective time series analysis of meteorological variables (rainfall, air temperature), hydrological variables (discharge, suspended sediments, FIB counts, water temperature), and the number of diarrheal disease cases reported at 6 health centers located in the 5 southern districts of the Luang Prabang Province, Lao PDR. We also examined the socio-demographic factors potentially affecting vulnerability to the effect of the climate factors, such as drinking water sources, hygiene habits, and recreational water exposure.ResultsUsing thus a mixed methods approach, we found E. coli to be present all year long (100–1,000 Most Probable Number or MPN 100 mL-1) indicating that fecal contamination is ubiquitous and constant. We found that populations switch their water supply from wells to surface water during drought periods, the latter of which appear to be at higher risk of bacterial contamination than municipal water fountains. We thus found that water shortage in the Luang Prabang area triggers diarrhea peaks during the dry and hot season and that rainfall and aquifer refill ends the epidemic during the wet season. The temporal trends of reported daily diarrhea cases were generally bimodal with hospital admissions peaking in February-March and later in May-July. Annual incidence rates were higher in more densely populated areas and mostly concerned the 0–4 age group and male patients.ConclusionsWe found that anthropogenic drivers, such as hygiene practices, were at least as important as environmental drivers in determining the seasonal pattern of a diarrhea epidemic. For diarrheal disease risk monitoring, discharge or groundwater level can be considered as relevant proxies. These variables should be monitored in the framework of an early warning system provided that a tradeoff is found between the size of the monitored catchment and the frequency of the measurement.

Urogenital schistosomiasis transmission on Unguja Island, Zanzibar: characterisation of persistent hot-spots.

BackgroundElimination of urogenital schistosomiasis transmission is a priority for the Zanzibar Ministry of Health. Preventative chemotherapy together with additional control interventions have successfully alleviated much of the disease burden. However, a persistently high Schistosoma haematobium prevalence is found in certain areas. Our aim was to characterise and evaluate these persistent “hot-spots” of transmission and reinfection in comparison with low-prevalence areas, to support the intervention planning for schistosomiasis elimination in Zanzibar.MethodsPrevalences of S. haematobium were annually determined by a single urine filtration in schoolchildren from 45 administrative areas (shehias) in Unguja in 2012, 2013 and 2014. Coverage data for biannual treatment with praziquantel were available from ministerial databases and internal surveys. Among the 45 shehias, five hot-spot (≥ 15 % prevalence) and two low-prevalence (≤ 5 %) shehias were identified and surveyed in mid-2014. Human-water contact sites (HWCSs) and the presence of S. haematobium-infected and uninfected Bulinus globosus, as well as safe water sources (SWSs) and their reliability in terms of water availability were determined and mapped.ResultsWe found no major difference in the treatment coverage between persistent hot-spot and low-prevalence shehias. On average, there were considerably more HWCSs containing B. globosus in hot-spot than in low-prevalence shehias (n = 8 vs n = 2) and also more HWCSs containing infected B. globosus (n = 2 vs n = 0). There was no striking difference in the average abundance of SWSs in hot-spot and low-prevalence shehias (n = 45 vs n = 38) and also no difference when considering SWSs with a constant water supply (average: 62 % vs 62 %). The average number of taps with a constant water supply, however, was lower in hot-spot shehias (n = 7 vs n = 14). Average distances from schools to the nearest HWCS were considerably shorter in hot-spot shehias (n = 229 m vs n = 722 m).ConclusionThe number of HWCSs, their infestation with B. globosus and their distance to schools seem to play a major role for a persistently high S. haematobium prevalence in children. In addition to treatment, increasing access to reliably working taps, targeted snail control at HWCSs near schools and enhanced behaviour change measures are needed to reduce prevalences in hot-spot areas and to finally reach elimination.Trial registration ISRCTN48837681.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1847-0) contains supplementary material, which is available to authorized users.

The Role of Emotions in Drinking Recycled Water

As global freshwater supplies shrink, recycled drinking water (RDW) has become an increasingly important source of water supply. However, RDW remains an underinvested resource despite being a safe and reliable source of water. The dominant hypothesis is that RDW has been rejected on emotional grounds of disgust, a visceral psychological reaction known as the “yuck” factor. This paper investigates the role of emotions in technical decision-making and applies it to RDW implementation. It tests two specific hypotheses. First, that negative emotions affect the policy process through a negative “goal definition” of the problem, making it unattractive to stakeholders. Second, the emotional quality of policies can be manipulated by policy entrepreneurs. These hypotheses are tested on two cases of RDW—one failed and the other successful. It finds that narratives in the former are relatively low in emotional intensity, with themes such as sustainability and governance, whereas the second case displays narratives charged with anger, social injustice, and disgust. This emphasizes the role of narratives, especially when visceral reactions such as disgust and anger interact with larger social and political discourses. Finally, we offer policy implications on how understanding the role of emotions can help in the implementation of RDW.

Performance Improvement of Solar Water Stills by Using Reflectors

The lack of safe and clean drinking water sources is one of the problems faced in most rural communities in Zambia. Water in these communities is mostly obtained from shallow wells and rivers. However, this water might be potentially contaminated with harmful substances such as pathogenic bacteria and therefore, unsafe for drinking. Solar water distillation represents an important alternative to palliate problems of fresh water shortages. Solar water stills can be used to eliminate harmful substances from contaminated water by treating it using free solar energy before it can be consumed. Therefore, there is a need to improve solar still performance to produce a greater quantity of safe drinking water. One possible method to improve performance is through adding reflectors to solar stills. Reflectors improve performance by increasing the quantity of distillate by about 22.3 % at a water depth of 15 mm and about 2 9% at a water depth of 10 mm when compared to the distillate produced from a still without reflectors. The water produced using solar stills with reflectors was tested and adhered to World Health Organization (WHO) drinking water standards. This implies that solar distillation with reflectors could be adopted at a larger scale to produce safer drinking water at a reduced cost.

Water Governance in Bangladesh: An Evaluation of Institutional and Political Context

Water crises are often crises of governance. To address interrelated issues of securing access to sustainable sources of safe water for the world’s populations, scholar and practitioners have suggested fostering improved modes of water governance that support the implementation of integrated water resource management (IWRM). Recently, implementation of an IWRM approach was announced as a target for achieving Goal 6 of the Sustainable Development Goals (SDGs). This study employs an analytical hierarchy process with a SWOT analysis to assess the current institutional and political context of water governance in Bangladesh and evaluate IWRM as a means to achieve the SDGs.

COMMERCIAL DRINKING WATER QUALITY AND SAFETY IN BO CITY, SIERRA LEONE

Many people who lack reliable access to a quality and safe drinking water source in or near the home rely on commercial drinking water products, such as machine-filled sachet water, that may be of variable quality.A participatory geographic information system was used in conjunction with distribution point and vendor census in the study area to identify a total of 36 water sources across Bo city that are used for commercial water production. These include 6 water sources and the production facilities for 10 brands of machine-filled factory-produced water sachets as well as the 10 sources and finished samples for 10hand-tied plastic-bagged water producers. Water samples from all 16 water sources and 20 commercial water products purchased from randomly-selected retail outlets and street vendors were tested for microbiological and physicochemical properties. Workers at all of these facilities were also interviewed about their knowledge and practices.All of the machine-filled sachet waters were free of microbial contamination, but several of the hand- tied water sachets, all filled from unlined local wells, and had coliform bacteria. Both machine-filled sachet water and hand-tied sachet water had pH levels that were below the World Health Organization’s recommended range. Water with acidic pH can cause corrosion of the metal pipes used with wells and can release those potentially harmful minerals into drinking water. Water factory workers used a variety of water treatment methods to purify their products; hand-tied sachets generally used only cloth filters to purify the water and often stored water in open containers. Improved quality of commercial water products would improve health in Sierra Leone.

Water, sanitation and hygiene in wetlands. A case study from the Ewaso Narok Swamp, Kenya.

Wetlands can be both a blessing and a curse. They are beneficial sources of safe water and nutrition and places from which humans derive their livelihoods. At the same time, wetlands are known to be sources of disease-causing microorganisms and invertebrates that can threaten human health. Safe water, sanitation and personal hygiene (WASH) are crucial preconditions for the prevention of disease transmission. And of special importance for people living in wetlands, depending on and being exposed to them. WASH should be prioritized especially in those wetlands that are subject to intensive use, that have a poor sanitation infrastructure, and which at the same time only provide limited water resources. However, despite this critical importance, WASH in wetlands is not well characterized in literature. This study therefore aimed at providing insights into the water, sanitation and hygiene conditions and behavioural determinants of households in wetlands by presenting the case of a rural wetland in East Africa. The mixed method approach included a broad set of empirical data collected during a household survey (n=400), an observational WASH assessment (n=397) and in-depth interviews (n=20) conducted from January to March 2015 in Ewaso Narok Swamp in Kenya. Different user groups of the wetland were targeted. The study in Ewaso Narok Swamp showed that wetland users' water supply and storage, sanitation and personal hygiene conditions were inadequate for large parts of the community and significantly differed between groups. Whereas the WASH conditions of people working in the service sector were rather positive, for pastoralists, they were correspondingly negative. The WASH behaviour was also perceived to be inadequate influenced by a variety of determining factors. The observational index as applied in this study indicated to be a valuable, rapid and efficient tool for assessing domestic WASH and for detecting differences between different groups in wetlands. Combined with the quantitative and qualitative data, the approach served as a very helpful model to develop a multi-layered understanding of WASH conditions and related behaviour. The people in the researched wetland use by far less improved water sources and sanitation facilities than the nationwide average for rural populations. Since Ewaso Narok Swamp serves as a model case for the domestic WASH conditions in a rural wetland in semiarid East Africa, this fact make the study relevant not only at a national, but also at an international level. The results underline the previously formulated need of an integrative approach that first and foremost complements wetland management by public health interventions. In order to improve WASH conditions and to change behaviour in the long term, interventions should include the provision of clean water and sanitation infrastructure, as well as widespread health education. The approach proved to be useful for wetland environments and will be integrated into the development of a health impact assessment tool for wetlands. Moreover, it can be adopted in other contexts.

Groundwater Origins and Circulation Patterns Based on Isotopes in Challapampa Aquifer, Bolivia

Aridity and seasonality of precipitation are characteristics of the highland region in Bolivia. Groundwater becomes an important and safe source of water when surficial bodies are intermittent and affected by natural and anthropogenic contamination. Decades of exploitation of the Challapampa aquifer, combined with lack of information required to understand the groundwater circulation, represent a challenge for reservoir management. This study analyzes isotopic compositions of deuterium and oxygen-18 in different stages in the hydrologic cycle to assess flow patterns in the aquifer, especially in the alluvial fan of River Paria, where records are more extensive in space and time. Interpretations are based on existing and new data. Some implications, such as the age of water, the evaporation effect in groundwater and some thermal intrusions are supported by stable isotopes, tritium, radiocarbon, and electrical conductivity records. New results confirm that modern precipitation over the mountains surrounding the study area is the most important origin of water for shallow aquifers until exploited depths, 100 m below surface. The origin of water in deeper depths, 400 m, seems related to infiltration at higher altitudes and longer residence times.

Undergraduate students' contributions to health service delivery through community-based education: A qualitative study by the MESAU Consortium in Uganda.

BackgroundIt has been realised that there is need to have medical training closer to communities where the majority of the population lives in order to orient the trainees’ attitudes towards future practice in such communities. Although community based education (CBE) has increasingly been integrated into health professions curricula since the 1990s, the contribution students make to service delivery during CBE remains largely undocumented. In this study, we examined undergraduate health professions students’ contribution to primary health care during their CBE placements.MethodsThis was a qualitative study involving the Medical Education for Equitable Services to All Ugandans consortium (MESAU). Overall, we conducted 36 Focus Group Discussions (FGDs): one each with youth, men and women at each of 12 CBE sites. Additionally, we interviewed 64 community key-informants. All data were audio-recorded, transcribed and analysed using qualitative data analysis software Atlas.ti Ver7.ResultsTwo themes emerged: students’ contribution at health facility level and students’ contribution at community level. Under theme one, we established that students were not only learning; they also contributed to delivery of health services at the facilities. Their contribution was highly appreciated especially by community members. Students were described as caring and compassionate, available on time and anytime, and as participating in patient care. They were willing to share their knowledge and skills, and stimulated discussion on work ethics. Under the second theme, students were reported to have participated in water, sanitation, and hygiene education in the community. Students contributed to maintenance of safe water sources, educated communities on drinking safe water and on good sanitation practices (hand washing and proper waste disposal). Hygiene promotion was done at household level (food hygiene, hand washing, cleanliness) and to the public. Public health education was extended to institutions. School pupils were sensitised on various health-related issues including sexuality and sexual health.ConclusionHealth professions students at the MESAU institutions contribute meaningfully to primary health care delivery. We recommend CBE to all health training programs in sub-Saharan Africa.

Access to safe drinking water and human health: empirical evidence from rural Bhutan

Provision of safe drinking water is essential for the promotion of human well-being. This paper makes an attempt to examine the patterns of access to drinking water, identify and analyze the factors that influence households access to safe drinking water sources, and analyze factors determining the extent of households travel to fetch drinking water, and assess the effects of access to safe drinking water on human health in Bhutan, using the data from the Bhutan Living Standard Survey 2012 (BLSS 2012). For this, various methodological tools have been adopted such as logistic regression model, censored least absolute deviation model, and the propensity score matching (PSM) approach. The logistic regression results show that households with educated, younger, and male members are more likely to have access to safe drinking water. Wealthier households also prefer safe drinking water than their poorer counterparts. The PSM results suggest that households having access to safe drinking water have fewer stomach disorders and skin diseases, and are likely to incur less expenditure on medicine. Keeping these findings in mind, the paper suggests that the Bhutanese government should invest in water infrastructure, which may lead to a significant reduction in water-borne diseases and health expenditure.

Urinary schistosomiasis among preschool children in Malengachanzi, Nkhotakota District, Malawi: Prevalence and risk factors.

This study was designed to determine the prevalence of and risk factors for schistosomiasis among a group of preschool children in Malawi. Schistosomiasis burden among preschoolers in Malawi is not well documented in the literature. This study used field research (in the form of a snail survey), laboratory work (urinalysis and microscopy for parasite identification), and questionnaire-guided interviews to determine the prevalence of and risk factors for urinary schistosomiasis among children, aged between 6 and 60 months, in Malengachanzi, Nkhotakota District, Malawi. Urinary schistosomiasis prevalence among preschool children was 13%. Of the factors evaluated, only age (P = 0.027) was statistically significantly associated with urinary schistosomiasis risk. Four-year-old preschool children were five times more likely to contract urinary schistosomiasis than twoyear-old children (odds ratio [OR] = 5.255; 95% confidence interval [CI] = 1.014-27.237; P = 0.048). Increased contact with infested water among older children likely explains much of their increased risk. Infestation was evidenced by the presence of infected Bulinus globosus snails in the water contact points surveyed. Multiple regression analysis showed that visiting water contact sites daily (OR = 0.898, 95% CI = 0.185-4.350, P = 0.894), bathing in these sites (OR = 9.462, 95% CI = 0.036-0.00, P = 0.430) and lack of knowledge, among caregivers, regarding the causes of urinary schistosomiasis (OR = 0.235, 95% CI = 0.005-1.102, P = 0.066) posed statistically insignificant risk increases for preschoolers contracting urinary schistosomiasis. Urinary schistosomiasis was prevalent among preschool children in Malengachanzi, Nkhotakota District. Contact with infested water puts these children and the general population at risk of infection and reinfection. Inclusion of preschool children in treatment programmes should be considered imperative, along with safe treatment guidelines. To prevent infection, the population in the area should be provided with health education and safe alternative water sources.

Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples.

A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources.