| 1. |
- Boakye-Ansah, A. S., et al.
(författare)
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Inequalities in microbial contamination of drinking water supplies in urban areas : The case of Lilongwe, Malawi
- 2016
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 14:5, s. 851-863
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Tidskriftsartikel (refereegranskat)abstract
- Over past decades strategies for improving access to drinking water in cities of the Global South have mainly focused on increasing coverage, while water quality has often been overlooked. This paper focuses on drinking water quality in the centralized water supply network of Lilongwe, the capital of Malawi. It shows how microbial contamination of drinking water is unequally distributed to consumers in low-income (unplanned areas) and higher-income neighbourhoods (planned areas). Microbial contamination and residual disinfectant concentration were measured in 170 water samples collected from in-house taps in high-income areas and from kiosks and water storage facilities in low-income areas between November 2014 and January 2015. Faecal contamination (Escherichia coli) was detected in 10% of the 40 samples collected from planned areas, in 59% of the 64 samples collected from kiosks in the unplanned areas and in 75% of the 32 samples of water stored at household level. Differences in water quality in planned and unplanned areas were found to be statistically significant at p < 0.05. Finally, the paper shows how the inequalities in microbial contamination of drinking water are produced by decisions both on the development of the water supply infrastructure and on how this is operated and maintained.
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| 2. |
- Börjesson, Stefan, 1979-, et al.
(författare)
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Genes encoding tetracycline resistance in a full-scale municipal wastewater treatment plant investigated during one year
- 2010
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 8:2, s. 247-256
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Tidskriftsartikel (refereegranskat)abstract
- Tetracycline-resistant bacteria and genes encoding tetracycline resistance are common in anthropogenic environments. We studied how wastewater treatment affects the prevalence and concentration of two genes, tetA and tetB, that encode resistance to tetracycline. Using real-time polymerase chain reaction (PCR) we analysed wastewater samples collected monthly for one year at eight key-sites in a full-scale municipal wastewater treatment plant (WWTP). We detected tetA and tetB at each sampling site and the concentration of both genes, expressed per wastewater volume or per total-DNA, decreased over the treatment process. The reduction of tetA and tetB was partly the result of the sedimentation process. The ratio of tetA and tetB, respectively, to total DNA was lower in or after the biological processes. Taken together our data show that tetracycline resistance genes occur throughout the WWTP, and that the concentrations are reduced under conventional operational strategies.
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| 3. |
- Moreira, Nuno, et al.
(författare)
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Safe drinking water and waterborne outbreaks
- 2017
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1996-7829 .- 1477-8920. ; 15:1, s. 83-96
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Forskningsöversikt (refereegranskat)abstract
- The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000–2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.
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| 4. |
- Navarro, PC, et al.
(författare)
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Antibiotic resistance in environmental Escherichia coli - a simple screening method for simultaneous typing and resistance determination
- 2014
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Ingår i: Journal of water and health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 12:4, s. 692-701
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Tidskriftsartikel (refereegranskat)abstract
- We describe a simple and standardised screening system (AREB) for surveillance of antibiotic resistant bacteria in the environment. The system consists of 96 well microplates containing eight sets of breakpoint amounts of 10 different antibiotics. The incubated microplates are read by a desktop scanner and the plate images are analysed by special software that automatically presents the resistance data. The AREB method is combined with a rapid typing method, the PhenePlate system, which yields information on the diversity of the bacteria in the studied samples, and on the possible prevalence of resistant clones. In order to demonstrate the usage of AREB, a comparative study on the resistance situation among 970 Escherichia coli isolates from sewage and recipient water in Sweden, Norway and Chile, was performed. Resistance rates to all antibiotics were markedly higher in hospital sewage than in other samples. Our data indicate that the AREB system is useful for comparing resistance rates among E. coli and other environmental indicator bacteria in different countries/regions. Simple handling and automatic data evaluation, combined with low cost, facilitate large studies involving several thousands of isolates.
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| 5. |
- Ngubane, Zesizwe, et al.
(författare)
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Water quality modelling and quantitative microbial risk assessment for uMsunduzi River in South Africa
- 2022
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1996-7829 .- 1477-8920. ; 20:4, s. 641-656
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Tidskriftsartikel (refereegranskat)abstract
- South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R-2 of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organisation (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.
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| 6. |
- Nilsson, Per, et al.
(författare)
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SCADA data and the quantification of hazardous events for QMRA
- 2007
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 5, s. 99-105
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to assess the use of on-line monitoring to support the QMRA at water treatment plants studied in the EU MicroRisk project. SCADA data were obtained from diary records, grab three Catchment-to-Tap Systems (CTS) along with system descriptions, sample data and deviation reports. Particular attention was paid to estimating hazardous event frequency, duration and magnitude. Using Shewart and CUSUM we identified 'change-points' corresponding to events of between 10 min and > 1 month duration in timeseries data. Our analysis confirmed it is possible to quantify hazardous event durations from turbidity, chlorine residual and pH records and distinguish them from non-hazardous variability in the timeseries dataset. The durations of most 'events' were short-term (0.5-2.3 h). These data were combined with QMRA to estimate pathogen infection risk arising from such events as chlorination failure. its interpretation was While analysis of SCADA data alone could identify events provisionally, severely constrained in the absence of diary records and other system information. SCADA data analysis should only complement traditional water sampling, rather than replace it. More work on on-line data management, quality control and interpretation is needed before it can be used for event characterization routinely for event characterrisation.
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| 7. |
- Ottoson et. al., Jakob
(författare)
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Tracking the origin of faecal pollution in surface water. An ongoing project within the European Union research programme
- 2004
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Ingår i: Journal of Water and Health. - 1477-8920 .- 1996-7829. ; 2:4, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study are to generate knowledge about methods to track the sources of faecal pollution in surface waters, with the aim of having one or a few easy procedures applicable to different geographic areas in Europe. For this, a first field study using already proposed methods (genotypes of F-specific RNA bacteriophages, bacteriophages infecting Bacteroides fragilis, phenotypes of faecal coliforms and enterococci, and sterols) has been done in five areas representing a wide array of conditions in Europe. The present faecal indicators (faecal coliforms, enterococci, sulfite reducing clostridia and somatic coliphages) have also been included in this first field study. At the same time some emerging methods have been settled or adapted to water samples and assayed in a limited number of samples. The results of this first field study indicate that no single parameter alone is able to discriminate the sources, human or non-human, of faecal pollution, but that a 'basket' of 4 or 5 parameters, which includes one of the present faecal indicators, will do so. In addition, numerical analysis of the data shows that this 'basket' will allow the successful building of predictive models. Both the statistical analyses and the studied predictive models indicate that genotype II of F-specific RNA bacteriophages, the coprostanol and the ratio coprostanol: coprostanol+epicoprostanol are, out of the studied parameters, those with a greater discriminating power. Either because unsuccessful adaptation of the methods to water samples or because the preliminary assays in water samples indicated low discriminating capability, only three (sorbitol-fermenting bifidobacteria, some species of bifidobacteria detected by PCR with specific primers and phages infecting Bacteroides tethaiotaomicron) of the newly assayed methods have been considered for a second field study, which is currently underway. Expectations are that these new tools will minimize the number of parameters in the 'basket', or at least minimize the difficulty in assaying them
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| 8. |
- Perez Mercado, Luis Fernando, et al.
(författare)
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Pathogens in crop production systems irrigated with low-quality water in Bolivia
- 2018
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 16, s. 980-990
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Tidskriftsartikel (refereegranskat)abstract
- In dry areas, the need for irrigation to ensure agricultural production determines the use of all available water sources. However, the water sources used for irrigation are often contaminated by untreated or minimally treated wastewater. Microbial risks from reusing wastewater for vegetable irrigation can be addressed by installing environmental barriers that pathogens must cross to reach humans in the reuse system. Knowledge of pathogen flows inside the system and pathogen removal potential is the first step towards devising a risk management strategy. This study assessed microbe prevalence in farming systems in the Bolivian highlands that use wastewater-polluted sources for irrigation of lettuce. Samples of soil, lettuce and different water sources used in the farming systems were taken during one crop season and concentrations of coliphages, Escherichia coli and helminth eggs were measured. The results showed high spread of these microorganisms throughout the whole system. There was a significant correlation between microbial quality of water and of the harvested produce for several microorganisms. The microbial prevalence in protected shallow wells was found to be significantly lower than in other water sources. These findings can help formulate feasible risk management strategies in contexts where conventional technologies for microbial removal are not possible.
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| 9. |
- Ridderstedt, Frida, et al.
(författare)
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Sick leave due to diarrhea caused by contamination of drinking water supply with Cryptosporidium hominis in Sweden : a retrospective study
- 2018
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 16:5, s. 704-710
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Tidskriftsartikel (refereegranskat)abstract
- We investigated sick leave from work, studies, preschool, and kindergarten occurring between 1 November 2010 and 31 January 2011 and associated with a waterborne outbreak of diarrhea caused by Cryptosporidium hominis in late November 2010 in Ostersund, Sweden with 45.2% of 60,000 residents being symptomatic. A questionnaire defining acute watery diarrhoea and/or >= 3 diarrhea episodes/day as cryptosporidiosis was sent to 1,508 residents in late January 2011 (response rate 69.2%). Among adults aged 18-60 years, 24.0% took sick leave for a mean of 4.6 (SD +/- 4.0) days due to cryptosporidiosis, and an additional 10.6% were absent from work a mean of 4.0 (+/- 2.2) days to care for symptomatic children. Among children (aged <= 17 years), 35.0% stayed home sick from kindergarten/preschool or school/university for a mean of 5.2 (+/- 3.8) days resulting in 5.1 (+/- 4.4) days of absence from work per sick child shared between parents/guardians. The estimated total number of sick leave days was 50,000 for adults and 20,700 for children, with an estimated direct cost of (sic) 7 million for employers. The potential impact on society of sick leave caused by waterborne diseases must be considered in decisions regarding the quality of drinking water.
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| 10. |
- Schönning, Caroline, et al.
(författare)
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Microbial risk assessment of local handling and reuse of human faeces
- 2007
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Ingår i: Journal of Water and Health. - : I W A Publishing. - 1477-8920 .- 1996-7829. ; 5:1, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- Dry urine-diverting toilets may be used in order to collect excreta for the utilisation of nutrients. A quantitative microbial risk assessment was conducted in order to evaluate the risks of transmission of infectious disease related to the local use of faeces as a fertiliser. The human exposures evaluated included accidental ingestion of small amounts of faeces, or a mixture of faeces and soil, while emptying the storage container and applying the material in the garden, during recreational stays to the garden, and during gardening. A range of pathogens representing various groups of microorganisms was considered. Results showed that 12-months' storage before use was sufficient for the inactivation of most pathogens to acceptable levels. When working or spending time in the garden the annual risk of infection by Ascaris was still slightly above 10-4 in these scenarios, although the incidence rate for Ascaris is very low in the population in question. Measures to further reduce the hygienic risks include longer storage, or treatment, of the faeces. The results can easily be extended to other regions with different incidence rates.
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