RESUMO
The development of low-cost tests for Escherichia coli is hampered by the expense and limited choice of enzyme substrates. Most chromogenic substrates are required in costly amounts, while fluorogenic substrates require an additional apparatus (e.g., an ultraviolet lamp) to be detected. Herein, we propose an alternative chromogenic substrate, resorufin ß-d-glucuronide (REG), which is exceptionally sensitive and may be employed in very small amounts. We show that REG can be produced similarly to other simple glucuronides and should therefore be no more expensive. The compound is used by both healthy and injured E. coli, resulting in a pronounced color change from orange to a bright pink. Because the released dye (resorufin) has a high extinction coefficient, substantially lower amounts are needed than for commercially available substrates. The potential of this substrate is demonstrated by a presence/absence test requiring just 0.1 mg of REG/100 mL of water sample, one hundredth of the quantity needed for common chromogenic substrates, with an estimated bulk cost of ≤0.1 U.S. cents/test. REG shows promise as a chromogenic substrate for E. coli detection and should be considered in the development of new water tests, especially for low-income settings.
Assuntos
Compostos Cromogênicos/síntese química , Água Potável/microbiologia , Escherichia coli/isolamento & purificação , Oxazinas/síntese química , Microbiologia da Água , Técnicas Bacteriológicas , Compostos Cromogênicos/química , Oxazinas/químicaRESUMO
INTRODUCTION: Measuring inequality in access to safe drinking-water and sanitation is proposed as a component of international monitoring following the expiry of the Millennium Development Goals. This study aims to evaluate the utility of census data in measuring geographic inequality in access to drinking-water and sanitation. METHODS: Spatially referenced census data were acquired for Colombia, South Africa, Egypt, and Uganda, whilst non-spatially referenced census data were acquired for Kenya. Four variants of the dissimilarity index were used to estimate geographic inequality in access to both services using large and small area units in each country through a cross-sectional, ecological study. RESULTS: Inequality was greatest for piped water in South Africa in 2001 (based on 53 areas (N) with a median population (MP) of 657,015; D = 0.5599) and lowest for access to an improved water source in Uganda in 2008 (N = 56; MP = 419,399; D = 0.2801). For sanitation, inequality was greatest for those lacking any facility in Kenya in 2009 (N = 158; MP = 216,992; D = 0.6981), and lowest for access to an improved facility in Uganda in 2002 (N = 56; MP = 341,954; D = 0.3403). Although dissimilarity index values were greater for smaller areal units, when study countries were ranked in terms of inequality, these ranks remained unaffected by the choice of large or small areal units. International comparability was limited due to definitional and temporal differences between censuses. CONCLUSIONS: This five-country study suggests that patterns of inequality for broad regional units do often reflect inequality in service access at a more local scale. This implies household surveys designed to estimate province-level service coverage can provide valuable insights into geographic inequality at lower levels. In comparison with household surveys, censuses facilitate inequality assessment at different spatial scales, but pose challenges in harmonising water and sanitation typologies across countries.
Assuntos
Água Potável/normas , Saneamento/normas , Abastecimento de Água/normas , Estudos Transversais , Países em Desenvolvimento , Sistemas de Informação Geográfica , Mapeamento Geográfico , Humanos , Fatores SocioeconômicosRESUMO
Safe drinking water access is a human right, but data on safely managed drinking water services (SMDWS) is lacking for more than half of the global population. We estimate SMDWS use in 135 low- and middle-income countries (LMICs) at subnational levels with a geospatial modeling approach, combining existing household survey data with available global geospatial datasets. We estimate that only one in three people used SMDWS in LMICs in 2020 and identified fecal contamination as the primary limiting factor affecting almost half of the population of LMICs. Our results are relevant for raising awareness about the challenges and limitations of current global monitoring approaches and demonstrating how globally available geospatial data can be leveraged to fill data gaps and identify priority areas in LMICs.
Assuntos
Países em Desenvolvimento , Água Potável , Mapeamento Geográfico , Abastecimento de Água , HumanosRESUMO
The presence/absence hydrogen sulphide test (P/A H2S) is widely used as a low-cost alternative faecal indicator test in remote and resource-poor settings. The aim of the paper is to assess how bacterial density and sample volume affect its accuracy. Based on a systematic search, we identified studies that tested water samples (n = 2,034) using both the P/A H2S test and recognised tests for thermotolerant coliforms (TTC) or Escherichia coli. We calculated P/A H2S test specificity and sensitivity against a range of TTC and E. coli densities. For two studies, we compared this with sensitivity and specificity estimates for simulated 100 and 20 ml presence/absence tests. For most of the 19 included studies, as the threshold used to define contamination increased from 1 to 100 cfu/100 ml, P/A H2S test sensitivity increased but specificity decreased. Similarly, the simulation indicated that increasing test volumes from 20 to 100 ml increased sensitivity but reduced specificity. There was potential for bias, for example from lack of blinding during test interpretation, in most of the studies reviewed. In assessing the P/A H2S test as an alternative to standard methods, careful consideration of likely indicator bacteria levels and sample volume is required.
Assuntos
Bactérias/metabolismo , Monitoramento Ambiental/métodos , Sulfeto de Hidrogênio/metabolismo , Microbiologia da Água , Abastecimento de Água/normasRESUMO
Achieving a high level of COVID-19 vaccination coverage in a conflict-affected setting is challenging. The objective of this paper is to shed further light on the main determinants of vaccination coverage using a large, cross-sectional sample (October-November 2022) of over 17,000 adults in Syria. We find evidence that certain demographic and socioeconomic characteristics describe a core set of vaccination personas. Men, older respondents, and those who are more educated and trust information received from healthcare authorities are more likely to be vaccinated. Healthcare workers in this sample are highly vaccinated. Furthermore, respondents with more positive views towards COVID-19 vaccines are also more likely to be willing to be vaccinated. By contrast, respondents who believe that vaccines are associated with significant side effects are also more likely to refuse vaccination. In addition, younger respondents and women, as well as those with a lower level of education, are more likely to refuse to be vaccinated. Respondents with a neutral attitude towards vaccines are also more likely to be undecided, whereas respondents who are refusing to get vaccinated are more likely to trust the information received from private doctors, private clinics, as well as social media and, more broadly, the internet.
RESUMO
Sustainable Development Goal target 6.2 calls for universal access to adequate and equitable sanitation, setting a more ambitious standard for 'safely managed sanitation services'. On-site sanitation systems (e.g., septic tanks) are widely used in low- and middle-income countries (LMICs). However, the lack of indicators for assessing fecal exposure risks presents a barrier to monitoring safely managed services. Furthermore, geographic diversity and frequency of disasters require a more nuanced approach to risk-informed decision-making. Taking Indonesia as an example, the purpose of this paper is to provide insights into current status and practices for on-site sanitation services in the contexts of LMICs. Using a dataset from a national socio-economic survey (n = 295,155) coupled with village census (n = 83,931), we assessed (1) household sanitation practices across Indonesia stratified by city-level population density and meteorological factors, (2) factors associated with septic tank emptying practice, and (3) inequalities in potential fecal exposure as measured by population density and WASH access by wealth quintile. We found a high reliance on on-site sanitation facilities (80.0%), almost half of which are assumed to be 'uncontained' septic tanks and one in ten facilities discharging untreated waste directly into the environment. The most densely populated areas had the highest rates of septic tank emptying, though emptying rates were just 17.0%, while in the lowest population density group, emptying was rarely reported. Multivariate regression analysis demonstrated an association between flooding and drought occurrence and septic tank emptying practice. Higher groundwater usage for drinking among poorer households suggests unsafe sanitation may disproportionally affect the poor. Our study underscores the urgent need to strengthen the monitoring of on-site sanitation in LMICs by developing contextualized standards. Furthermore, the inequalities in potential fecal exposure require greater attention and tailored support mechanisms to ensure the poorest gain access to safely managed sanitation services.
Assuntos
Características da Família , Saneamento , Fezes , Humanos , Indonésia , Pobreza , Abastecimento de ÁguaRESUMO
The Multidimensional Poverty Index is used increasingly to measure poverty in developing countries. The index is constructed using selected indicators that cover health, education, and living standards dimensions. The accuracy of this tool, however, depends on how each indicator is measured. This study explores the effect of accounting for water quality in multidimensional poverty measurement. Access to drinking water is traditionally measured by water source types. The study uses a more comprehensive measure, access to safely managed drinking water services, which are free from E. coli contamination, available when needed and accessible on premises in line with Sustainable Development Goal target 6.1. The study finds that the new measure increases national multidimensional headcount poverty by 5-13 percentage points, which would mean that 5-13 million more people are multidimensionally poor. It also increases the poverty level in urban areas to a greater extent than in rural areas. The finding is robust to changes in water contamination risk levels and Multidimensional Poverty Index aggregation approaches and weighting structures.
Assuntos
Água Potável/normas , Pobreza , Qualidade da Água/normas , Água Potável/microbiologia , Escherichia coli/isolamento & purificação , Escherichia coli/patogenicidade , Etiópia/epidemiologia , Características da Família , Feminino , Humanos , Masculino , População Rural , Fatores Socioeconômicos , Poluição da ÁguaRESUMO
Water point mapping databases, generated through surveys of water sources such as wells and boreholes, are now available in many low and middle income countries, but often suffer from incomplete coverage. To address the partial coverage in such databases and gain insights into spatial patterns of water resource use, this study investigated the use of a maximum entropy (MaxEnt) approach to predict the geospatial distribution of drinking-water sources, using two types of unimproved sources in Kenya as illustration. Geographic locations of unprotected dug wells and surface water sources derived from the Water Point Data Exchange (WPDx) database were used as inputs to the MaxEnt model alongside geological/hydrogeological and socio-economic covariates. Predictive performance of the MaxEnt models was high (all > 0.9) based on Area Under the Receiver Operator Curve (AUC), and the predicted spatial distribution of water point was broadly consistent with household use of these unimproved drinking-water sources reported in household survey and census data. In developing countries where geospatial datasets concerning drinking-water sources often have necessarily limited resolution or incomplete spatial coverage, the modelled surface can provide an initial indication of the geography of unimproved drinking-water sources to target unserved populations and assess water source vulnerability to contamination and hazards.
Assuntos
Censos , Bases de Dados Factuais , Água Potável , Poços de Água , Humanos , QuêniaRESUMO
BACKGROUND: The Sustainable Development Goals (SDGs) require household survey programmes such as the UNICEF-supported Multiple Indicator Cluster Surveys (MICS) to enhance data collection to cover new indicators. This study aims to evaluated methods for assessing water quality, water availability, emptying of sanitation facilities, menstrual hygiene management and the acceptability of water quality testing in households which are key to monitoring SDG targets 6.1 and 6.2 on drinking Water, Sanitation and Hygiene (WASH) and emerging issues. METHODS: As part of a MICS field test, we interviewed 429 households and 267 women age 15-49 in Stann Creek, Belize in a split-sample experiment. In a concurrent qualitative component, we conducted focus groups with interviewers and cognitive interviews with respondents during and immediately following questionnaire administration in the field to explore their question comprehension and response processes. FINDINGS: About 88% of respondents agreed to water quality testing but also desired test results, given the potential implications for their own health. Escherichia coli was present in 36% of drinking water collected at the source, and in 47% of samples consumed in the household. Both questions on water availability necessitated probing by interviewers. About one quarter of households reported emptying of pit latrines and septic tanks, though one-quarter could not provide an answer to the question. Asking questions on menstrual hygiene was acceptable to respondents, but required some clarification and probing. CONCLUSIONS: In the context of Belize, this study confirmed the feasibility of collecting information on the availability and quality of drinking water, emptying of sanitation facilities and menstrual hygiene in a multi-purpose household survey, indicating specific areas to improve question formulation and field protocols. Improvements have been incorporated into the latest round of MICS surveys which will be a major source of national data for monitoring of SDG targets for drinking water, sanitation and hygiene and emerging issues for WASH sector programming.
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Conservação dos Recursos Naturais , Água Potável , Saneamento/estatística & dados numéricos , Belize , Escherichia coli/isolamento & purificação , Feminino , Humanos , Menstruação , Inquéritos e Questionários , Microbiologia da ÁguaRESUMO
Following the recent expiry of the United Nations' 2015 Millennium Development Goals (MDGs), new international development agenda covering 2030 water, sanitation and hygiene (WASH) targets have been proposed, which imply new demands on data sources for monitoring relevant progress. This study evaluates drinking-water and sanitation classification systems from national census questionnaire content, based upon the most recent international policy changes, to examine national population census's ability to capture drinking-water and sanitation availability, safety, accessibility, and sustainability. In total, 247 censuses from 83 low income and lower-middle income countries were assessed using a scoring system, intended to assess harmonised water supply and sanitation classification systems for each census relative to the typology needed to monitor the proposed post-2015 indicators of WASH targets. The results signal a lack of international harmonisation and standardisation in census categorisation systems, especially concerning safety, accessibility, and sustainability of services in current census content. This suggests further refinements and harmonisation of future census content may be necessary to reflect ambitions for post-2015 monitoring.
Assuntos
Água Potável/normas , Saneamento/classificação , Censos , Países em Desenvolvimento/estatística & dados numéricos , Saúde Global/classificação , Saúde Global/normas , Programas Gente Saudável/normas , Humanos , Saneamento/normas , Inquéritos e Questionários , Banheiros/normas , Banheiros/estatística & dados numéricosRESUMO
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.
Assuntos
Bactérias , Água Potável/microbiologia , Microbiologia da Água , Abastecimento de Água/métodos , Países em Desenvolvimento , Características da Família , Fezes/microbiologiaRESUMO
BACKGROUND: Packaged water products provide an increasingly important source of water for consumption. However, recent studies raise concerns over their safety. OBJECTIVES: To assess the microbial safety of packaged water, examine differences between regions, country incomes, packaged water types, and compare packaged water with other water sources. METHODS: We performed a systematic review and meta-analysis. Articles published in English, French, Portuguese, Spanish and Turkish, with no date restrictions were identified from online databases and two previous reviews. Studies published before April 2014 that assessed packaged water for the presence of Escherichia coli, thermotolerant or total coliforms were included provided they tested at least ten samples or brands. RESULTS: A total of 170 studies were included in the review. The majority of studies did not detect fecal indicator bacteria in packaged water (78/141). Compared to packaged water from upper-middle and high-income countries, packaged water from low and lower-middle-income countries was 4.6 (95% CI: 2.6-8.1) and 13.6 (95% CI: 6.9-26.7) times more likely to contain fecal indicator bacteria and total coliforms, respectively. Compared to all other packaged water types, water from small bottles was less likely to be contaminated with fecal indicator bacteria (OR = 0.32, 95%CI: 0.17-0.58) and total coliforms (OR = 0.10, 95%CI: 0.05, 0.22). Packaged water was less likely to contain fecal indicator bacteria (OR = 0.35, 95%CI: 0.20, 0.62) compared to other water sources used for consumption. CONCLUSIONS: Policymakers and regulators should recognize the potential benefits of packaged water in providing safer water for consumption at and away from home, especially for those who are otherwise unlikely to gain access to a reliable, safe water supply in the near future. To improve the quality of packaged water products they should be integrated into regulatory and monitoring frameworks.
Assuntos
Água Potável/microbiologia , Fezes/microbiologia , Microbiologia da Água , Escherichia coli/isolamento & purificação , Escherichia coli/patogenicidade , Humanos , Embalagem de Produtos , Qualidade da ÁguaRESUMO
Packaged drinking water (PW) sold in bottles and plastic bags/sachets is widely consumed in low- and middle-income countries (LMICs), and many urban users in sub-Saharan Africa (SSA) rely on packaged sachet water (PSW) as their primary source of water for consumption. However, few rigorous studies have investigated PSW quality in SSA, and none have compared PSW to stored household water for consumption (HWC). A clearer understanding of PSW quality in the context of alternative sources is needed to inform policy and regulation. As elsewhere in SSA, PSW is widely consumed in Sierra Leone, but government oversight is nearly nonexistent. This study examined the microbiological and chemical quality of a representative sample of PSW products in Freetown, Sierra Leone at packaged water manufacturing facilities (PWMFs) and at points of sale (POSs). Samples of HWC were also analyzed for comparison. The study did not find evidence of serious chemical contamination among the parameters studied. However, 19% of 45 PSW products sampled at the PWMF contained detectable Escherichia coli (EC), although only two samples exceeded 10 CFU/100 mL. Concentrations of total coliforms (TC) in PSW (but not EC) increased along the supply chain. Samples of HWC from 60 households in Freetown were significantly more likely to contain EC and TC than PSW at the point of production (p<0.01), and had significantly higher concentrations of both bacterial indicators (p<0.01). These results highlight the need for additional PSW regulation and surveillance, while demonstrating the need to prioritize the safety of HWC. At present, PSW may be the least unsafe option for many households.
Assuntos
Água Potável/química , Água Potável/microbiologia , Qualidade da Água/normas , Abastecimento de Água/normas , Arsênio/análise , Qualidade de Produtos para o Consumidor/normas , Enterobacteriaceae/isolamento & purificação , Escherichia coli/isolamento & purificação , Fluoretos/análise , Concentração de Íons de Hidrogênio , Ferro/análise , Manganês/análise , Nitratos/análise , Porfirinas/análise , Serra Leoa , Microbiologia da Água , Purificação da Água/instrumentação , Purificação da Água/métodosRESUMO
Screening methods that use traditional genomic, transcriptional, proteomic and metabonomic signatures to characterize drug mechanisms are known. However, they are time consuming and require specialized equipment. Here, we present a high-throughput multichannel sensor platform that can profile the mechanisms of various chemotherapeutic drugs in minutes. The sensor consists of a gold nanoparticle complexed with three different fluorescent proteins that can sense drug-induced physicochemical changes on cell surfaces. In the presence of cells, fluorescent proteins are rapidly displaced from the gold nanoparticle surface and fluorescence is restored. Fluorescence 'turn on' of the fluorescent proteins depends on the drug-induced cell surface changes, generating patterns that identify specific mechanisms of cell death induced by drugs. The nanosensor is generalizable to different cell types and does not require processing steps before analysis, offering an effective way to expedite research in drug discovery, toxicology and cell-based sensing.
Assuntos
Antineoplásicos/administração & dosagem , Monitoramento de Medicamentos/instrumentação , Nanotecnologia/instrumentação , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Espectrometria de Fluorescência/instrumentação , Animais , Bioensaio/instrumentação , Linhagem Celular Tumoral , Desenho de Equipamento , Análise de Falha de Equipamento , Camundongos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
The cost and complexity of traditional methods for the detection of faecal indicator bacteria, including E. coli, hinder widespread monitoring of drinking water quality, especially in low-income countries and outside controlled laboratory settings. In these settings the problem is exacerbated by the lack of inexpensive media for the detection of E. coli in drinking water. We developed a new low-cost growth medium, aquatest (AT), and validated its use for the direct detection of E. coli in temperate and sub-tropical drinking waters using IDEXX Quanti-Tray®. AT was compared with IDEXX Colilert-18® and either EC-MUG or MLSB for detecting low levels of E. coli from water samples from temperate (n = 140; Bristol, UK) and subtropical regions (n = 50, Pretoria/Tshwane, South Africa). Confirmatory testing (n = 418 and 588, respectively) and the comparison of quantitative results were used to assess performance. Sensitivity of AT was higher than Colilert-18® for water samples in the UK [98.0% vs. 86.9%; p<0.0001] and South Africa [99.5% vs. 93.2%; p = 0.0030]. There was no significant difference in specificity, which was high for both media (>95% in both settings). Quantitative results were comparable and within expected limits. AT is reliable and accurate for the detection of E. coli in temperate and subtropical drinking water. The composition of the new medium is reported herein and can be used freely.