Diarrhoea prevention in Bolivia through point-of-use water treatment and safe storage: a promising new strategy.
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A novel water quality intervention that consists of point-of-use water disinfection, safe storage and community education was field tested in Bolivia. A total of 127 households in two periurban communities were randomized into intervention and control groups, surveyed and the intervention was distributed. Monthly water quality testing and weekly diarrhoea surveillance were conducted. Over a 5-month period, intervention households had 44% fewer diarrhoea episodes than control households (P = 0.002). Infants < 1 year old (P = 0.05) and children 5-14 years old (P = 0.01) in intervention households had significantly less diarrhoea than control children. Campylobacter was less commonly isolated from intervention than control patients (P = 0.02). Stored water in intervention households was less contaminated with Escherichia coli than stored water in control households (P < 0.0001). Intervention households exhibited less E. coli contamination of stored water and less diarrhoea than control households. This promising new strategy may have broad applicability for waterborne disease prevention. (+info)
Quality of water used for haemodialysis: bacteriological and chemical parameters.
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BACKGROUND: The bacterial and chemical contamination of dialysate fluids are important problems in haemodialysis therapy and may be caused by the water used for dialysate preparation. METHODS: We performed a survey of the microbiological and chemical quality of the water used in seven dialysis wards. Special attention was paid to the effects of each water treatment step, for example ion exchange, reverse osmosis and UV disinfection, on the number of bacteria (measured as colony forming units, CFU), the amount of endotoxin (endotoxin units, EU) and various chemical parameters, the main focus being on calcium, magnesium, sulphate, aluminium and heavy metals. RESULTS: CFU values exceeding the European Pharmacopeia value, determined at an incubation temperature of 22 degrees C, were found in the samples of raw water (20.0%, n=25), after ion exchange (66.7%, n=12), after reverse osmosis (33.3%, n=18) and also in samples of the dialysis water taken at the inlets (12.5%, n=40) and outlets (50.0%, n=18) of the machines. Whereas all raw water samples from the wards showed high mean values for endotoxin (0.56-9.10 EU/ml) and the endotoxin levels were often enhanced after ion exchange (0.13- >9.49 EU/ml), treatment by reverse osmosis led to a satisfactory decrease in endotoxin in all samples (<0.03 EU/ml). Sufficient reductions in calcium, magnesium and sulphate could only be achieved by the combined application of ion exchange and reverse osmosis. Mercury contamination was observed in the samples after ion exchange at three treatment plants, this was possibly caused by polluted regenerants. Increased amounts of aluminium, copper and zinc were found in water samples from different sites in the treatment systems and were caused by materials in contact with the water. CONCLUSIONS: A sufficient chemical water purification treatment system should consist of ion exchange and reverse osmosis. Attention has to be paid to the suitability of materials in contact with the water and of the chemicals used, for example regenerants or corrosion inhibitors. From the microbiological point of view, a safety UV disinfection step in the water-treatment system is favourable. To avoid bacterial recontamination periodic cleaning and disinfecting of the water-treatment and distribution systems, as well as the dialysis machine are essential. There is the need for complete guidelines regarding dialysis water that include all relevant chemical and microbiological parameters. Based on this standard, periodic examination of the water after each treatment step has to be performed. (+info)
Distribution of fluoride and fluorosis in Ethiopia and prospects for control.
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A review and mapping of fluoride test data for 270 water sources in 126 communities and examination of the literature of fluorosis distribution in Ethiopia show that this health problem extends beyond the Rift Valley into some highland communities. Fluoride concentrations above 5.0 mg/l in the Rift Valley were found mostly in hot springs (100% of all sources), lakes (78%), shallow wells (54%) and boreholes (35%) and the lowest concentrations (below 1.5 mg/l) in springs and rivers. Analysis of hydrochemical, economic and demographic factors in the spatial distribution of high-fluoride domestic water sources indicates that the fluorosis problem has become more serious in the Rift Valley in recent decades. Considerable spatial variation in the occurrence of fluoride, even within the same communities, and the presence of some low-fluoride water sources in the Rift Valley offer possibilities for geochemical exploration for acceptable domestic sources. The defluoridation programme in the Wonji irrigation scheme illustrates the problems faced by a large rural community in a developing country. Possibilities for control are examined and recommendations made for the development of alternative water sources and promising defluoridation methods using locally available materials and technologies. (+info)
Drinking water source and chlorination byproducts in Iowa. III. Risk of brain cancer.
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The authors conducted a population-based case-control study in Iowa of 375 brain cancer patients and 2,434 controls. A postal questionnaire was used to gather information on lifetime residential history, sources of drinking water, beverage intake, and other potential risk factors. Exposure to chlorination byproducts in drinking water was estimated by combining questionnaire data with historical information from water utilities and trihalomethane levels in recent samples. The analysis included 291 cases (77.6%) and 1,983 controls (81.5%), for whom water quality information was available for at least 70% of lifetime years. Proxies represented 74.4% of cases. The mean number and mean duration of places of residence were comparable between direct and proxy respondents, suggesting little contribution to bias. After multivariate adjustment, odds ratios for brain cancer were 1.0, 1.1, 1.6, and 1.3 for exposure to chlorinated surface water of 0, 1-19, 20-39, and > or =40 years (p trend = 0.1). Among men, odds ratios were 1.0, 1.3, 1.7, and 2.5 (p trend = 0.04), and among women, 1.0, 1.0, 1.6, and 0.7 (p trend = 0.7)). Similar findings were found with estimates of average lifetime level of trihalomethanes. The association was stronger among men with above-median tap water consumption. These observations deserve further attention, especially in view of increasing glioma rates. (+info)
Solar disinfection of water reduces diarrhoeal disease: an update.
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349 Maasai children younger than 6 years old were randomised by alternate household to drink water either left in plastic bottles exposed to sunlight on the roof of the house or kept indoors (control). The trial was run in Maasai by Maasai community elders. Children drinking solar disinfected water had a significantly lower risk of severe diarrhoeal disease over 8705 two weekly follow up visits; two week period prevalence was 48.8% compared with 58.1% in controls, corresponding to an attributable fraction of 16.0%. While this reduction is modest, it was sustained over a year in free living children. It confirms solar disinfection as effective in vivo as a free, low technology, point of consumption method of improving water quality. The continuing use of solar disinfection by the community underlines the value of community participation in research. (+info)
Outbreak of viral gastroenteritis due to drinking water contaminated by Norwalk-like viruses.
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Heinavesi, a Finnish municipality with a population of 4860 inhabitants, had an outbreak of gastroenteritis in March 1998. On the basis of an epidemiologic survey, an estimated 1700-3000 cases of acute gastroenteritis occurred during the outbreak. Municipal water consumption was found to be associated with illness (risk ratio [RR]=3.5, 95% confidence interval, 3.11>RR>3.96). Norwalk-like virus (NLV) genogroup II (GGII) was identified in untreated water, treated water, and 4 tap water samples by use of reverse transcription-polymerase chain reaction. This was the first time NLVs had been detected in municipal tap water. Fifteen of 27 patient stool samples had NLV GGII, with an identical amplification product to that found in the water samples, indicating that the outbreak was caused by this virus. In some patients, NLV genogroup I was also encountered. This virus, however, could not be detected in the water samples. Inadequate chlorination contributed to the survival of the virus in the water. (+info)
Comparative survival of free shiga toxin 2-encoding phages and Escherichia coli strains outside the gut.
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The behavior outside the gut of seeded Escherichia coli O157:H7, naturally occurring E. coli, somatic coliphages, bacteriophages infecting O157:H7, and Shiga toxin 2 (Stx2)-encoding bacteriophages was studied to determine whether the last persist in the environment more successfully than their host bacteria. The ratios between the numbers of E. coli and those of the different bacteriophages were clearly lower in river water than in sewage of the area, whereas the ratios between the numbers of the different phages were similar. In addition, the numbers of bacteria decreased between 2 and 3 log units in in situ survival experiments performed in river water, whereas the numbers of phages decreased between 1 and 2 log units. Chlorination and pasteurization treatments that reduced by approximately 4 log units the numbers of bacteria reduced by less than 1 log unit the numbers of bacteriophages. Thus, it can be concluded that Stx2-encoding phages persist longer than their host bacteria in the water environment and are more resistant than their host bacteria to chlorination and heat treatment. (+info)
Biological warfare agents as threats to potable water.
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Nearly all known biological warfare agents are intended for aerosol application. Although less effective as potable water threats, many are potentially capable of inflicting heavy casualties when ingested. Significant loss of mission capability can be anticipated even when complete recovery is possible. Properly maintained field army water purification equipment can counter this threat, but personnel responsible for the operation and maintenance of the equipment may be most at risk of exposure. Municipal water treatment facilities would be measurably less effective. Some replicating (infectious) agents and a few biotoxins are inactivated by chlorine disinfection; for others chlorine is ineffective or of unknown efficacy. This report assesses the state of our knowledge of agents as potable water threats and contemplates the consequences of intentional or collateral contamination of potable water supplies by 18 replicating agents and 9 biotoxins known or likely to be weaponized or otherwise used as threats. (+info)