Estimation of pathogen concentrations in a drinking water source using hydrodynamic modelling and microbial source tracking

The faecal contamination of drinking water sources can lead to waterborne disease outbreaks. To estimate a potential risk for waterborne infections caused by faecal contamination of drinking water sources, knowledge of the pathogen concentrations in raw water is required. We suggest a novel approach to estimate pathogen concentrations in a drinking water source by using microbial source tracking data and fate and transport modelling. First, the pathogen (norovirus, Cryptosporidium, Escherichia coli O157/H7) concentrations in faecal contamination sources around the drinking water source Lake R?dasj?n in Sweden were estimated for endemic and epidemic conditions using measured concentrations of faecal indicators (E. coli and Bacteroidales genetic markers). Afterwards, the fate and transport of pathogens within the lake were simulated using a three-dimensional coupled hydrodynamic and microbiological model. This approach provided information on the contribution from different contamination sources to the pathogen concentrations at the water intake of a drinking water treatment plant. This approach addresses the limitations of monitoring and provides data for quantitative microbial risk assessment (QMRA) and risk management in the context of faecal contamination of surface drinking water sources.     

Municipal wastewater treatment plants as pathogen removal systems and as a contamination source of noroviruses and Enterococcus faecalis

Municipal wastewater treatment plants play a crucial role in reducing the microbial and pathogen load of human wastes before the end-products are discharged to surface waters (final effluent) or land spread (biosolids). This study investigated the occurrence frequency of noroviruses, Enterococcus faecalis and Enterococcus faecium in influent, final effluent and biosolids from four secondary wastewater treatment plants in northwestern Ireland (plants A-D) and observed the seasonal and spatial variation of the plant treatment efficiencies in the pathogen removals. It was noted that norovirus genogroup II was more resistant to the treatment processes than the norovirus genogroup I and other active viral particles, especially those in the discharge effluents. The percolating biofilm system at plant D resulted in better effluent quality than in the extended aerated activated sludge systems (plants A and B); primary biosolids produced at plant D may pose a higher health risk to the locals. The spread of norovirus genogroup II into the environment, irrespective of the wastewater treatment process, coincides with its national clinical predominance over norovirus genogroup I. This study provides important evidence that municipal wastewater treatment plants not only achieve pathogen removal but can also be the source of environmental pathogen contamination.     

广西南北两地水源水和饮用水中微囊藻毒素-LR含量调查

目的比较广西北回归线两侧的南宁地区和桂林地区水源水和饮用水中微囊藻毒素-LR(microcystin-LR,MC-LR)含量差异。方法于2017年采集南宁地区和桂林地区主要水源水及饮用水水样,采用酶联免疫吸附法(ELISA)检测水中MC-LR的含量。结果南宁地区与桂林地区水源水和饮用水中MC-LR平均含量均未超过我国地表水环境质量标准、饮用水卫生标准限值1μg/L。南北两地水库水中MC-LR平均含量均高于江河水、井水和山泉水(P<0.05)。南宁地区不同类型水源水MC-LR含量与桂林地区相比,水库水MC-LR平均含量较高,差异有统计学意义(P<0.05)。南北两地分散式供水末梢水中MC-LR平均含量均高于农村和城市集中式供水(P<0.05)。南宁地区的水源水和出厂水MC-LR平均含量分别为(0.256±0.048)、(0.210±0.025)μg/L,两者差异有统计学意义(P<0.05)。南宁地区水源水MC-LR含量在10月份达到峰值。结论广西南北两地水源水和饮用水中MC-LR含量均未超过国标中所规定的标准限值,南北两地水库水MC-LR含量存在明显差异,分散式供水MC-LR含量高于集中式供水。南宁地区水源水MC-LR平均含量高于出厂水,且在10月份达到峰值。提示需加强水源水和饮用水水质日常监测,秋季严格控制自来水处理工艺,以保证水质安全。     

Assessment and management of tap water lead contamination in Lower Saxony, Germany

Lead is known to have numerous adverse effects especially to infants and children. The intake of lead through drinking water is commonly due to metal corrosion in the peripheral water distribution system, especially the user's plumbing. The aim of this project was to assess the present state of drinking water contamination with lead in Lower Saxony and to promote replacement of lead pipes. For this purpose a project was initiated comprising three parts. First, a free examination of drinking water was offered in cooperation with local public health departments for private households with young women and families with children living in buildings constructed before 1974. Participants were asked to collect a cold tap water sample in their household after nocturnal stagnation and to complete a questionnaire. The collected samples were analysed by atomic absorption spectrometry for their lead concentration. Second, data from local public health departments on results of lead measurements, especially in buildings for the public, were collected and analysed. Finally a working group 'lead replacement' was initiated. In the project in total 2436 tap water samples from households were collected. Of these, 6.49% had lead concentrations exceeding 10 microg/l (recommended limit of the World Health Organization) and 2.79% had concentrations above the limit of the German drinking water ordinance (25 microg/l). There were remarkable regional differences in the frequency of tap water contamination. Multi-family houses were more frequently affected than single- and double-family houses.     

深圳市熟肉制品致病菌监测结果分析

目的:了解深圳市熟肉制品受致病菌污染的状况,为食源性疾病的预防和控制提供科学依据。方法:对酒店、超市和市场禽类熟肉制品随机采集360份样品,依据国标方法、荧光PCR方法及全自动微生物分析仪,对上述样品进行致病菌检测。结果:360份样品共检出致病菌38株,检出率10.56%,其中沙门菌4株、金黄色葡萄球菌32株、单增李斯特菌2株。酱卤类、烧烤类、白切类熟肉制品检出率分别为11.66%、3.33%、16.67%。结论:深圳市熟肉制品受致病菌污染严重,以金黄色葡萄球菌、沙门菌和单核李斯特菌污染为主;白切类熟肉制品受致病菌污染最为严重为16.67%;其次是酱卤类为11.66%;最后是烧烤类为3.33%。说明酒店、超市熟肉制品存在很大问题,应加大对熟肉制品监管力度,保证食品质量,确保消费者健康。     

我国部分城市水源水及末梢水中贾第鞭毛虫和隐孢子虫的污染状况调查

目的了解我国部分城市水源水、末梢水中贾第鞭毛虫和隐孢子虫(以下简称两虫)的污染情况。方法于2014年丰水期(8—10月)、枯水期(11—12月)分别选取我国北、南、中部地区的哈尔滨、合肥、北京三地,对其水源水及末梢水进行了两虫的检测。结果三地丰水期、枯水期的水源水、末梢水中均有两虫的检出。60件水源水中,贾第鞭毛虫和隐孢子虫的超标率分别为10.0%和26.7%;60件末梢水中,贾第鞭毛虫均达标,隐孢子虫的超标率为1.7%;枯、丰水期水源水隐孢子虫的超标率均高于贾第鞭毛虫,枯、丰水期水源水两虫的超标率均高于末梢水。结论三地区水源水、末梢水中均有两虫不同程度的污染。     

2010年通辽市食品污染物中致病菌污染状况分析

目的了解内蒙古通辽市大众消费量大、流通广的食品中主要食源性致病菌的污染情况,进行食品风险评估、确立风险管理决策,降低人群食源性疾病的发病率。方法卫生部2010年国家食源性致病菌监测工作手册。结果采集317份样品检测8种致病菌,在317份样品中检出沙门氏菌9株,检出率为3.00%;在183份样品中检出单核细胞增生李斯特菌15株,榆出率为8.20%：在150份样品检出金黄色葡萄菌13株检出率为8.67%;在75份样品中检出3株副溶血性弧菌,检出率为4.00%。皈崎肠杆菌、大肠0157：H7/NM、空肠弯曲菌、创伤弧菌均未检出。结论食品中存在的致病菌对人群构成潜在健康危害,应加强卫生监管、监测,预防食源性疾病的发生。     

Bacterial contamination of stored water and stored food: a potential source of diarrhoeal disease in West Africa

The food and water hygiene in two Liberian communities was studied in a house-to-house diarrhoea survey. The level of contamination with enterobacteria of drinking water stored in the households was significantly higher than at the water sources. Food hygiene standards were low, particularly in the urban slum where storage of cooked food for long periods led to bacterial multiplication at high levels. Infant foods were particularly heavily contaminated. It is concluded that when water supply programmes are planned, the presence of other risk factors for water-related diseases should be investigated. To ensure maximum health benefits, water projects should as a rule be accompanied by other interventions.     

Determining the source of fecal contamination in recreational waters

Public health departments bear the responsibility for investigating recreational water-associated disease outbreaks. Tracking the source of the disease is often problematic, however, because routine monitoring of recreational waters (for bacterial counts) is not source specific. The intent of the project reported here was to monitor Escherichia coli levels in a small recreational lake in Iowa and to determine their source. The authors monitored water samples for E. coli and used phenotypic methods to analyze multiple samples of lake water, well water, and known fecal sources. Moderate to high levels of E. coli were found in lake water samples from the swimming area throughout the summer. The highest levels of E. coli were found after rainfall events in both lake water samples and samples taken from monitoring wells. Phenotypic analyses indicated that likely sources of E. coli in the lake included both human and wildlife (goose) fecal material. The authors also found that the phenotype used to characterize E. coli isolated from geese frequenting this lake could not be used to characterize E. coli isolated from geese in a neighboring watershed. Identifying the source of fecal material will help authorities implement the proper preventive measures to avoid fecal contamination of the lake in the future.     

2009年湖州市食品中食源性致病菌污染调查分析

目的:了解湖州市食品中食源致病菌污染状况,为食品安全的危险性评估提供依据。方法:2009年对湖州市主要的集贸市场和超市采集生畜肉、生禽肉、即食食品、水产品4大类食品共计121份样品,按照国家食源性疾病监测网工作手册和浙江省疾病预防控制中心业务技术措施要点要求的检测方法进行沙门菌、大肠杆菌O157:H7、副溶血性弧菌、单核细胞增生李斯特菌、金黄色葡萄球菌、香港海鸥菌、空肠弯曲菌7种致病菌检测,菌株鉴定应用A T B细菌鉴定仪。结果:湖州市4大类食品121份样品中检出致病菌33株,检出率为27.27%,其中副溶血性弧菌29株,检出率24.79%,单增李斯特菌3株,检出率2.48%,沙门菌1株,检出率0.08%。结论:食品中存在食源性致病菌污染,是食源性疾病发生的潜在危险因素,应采取针对性措施提高食品安全。     

学校饮水机微生物污染状况

目的 掌握上海市闵行区学校饮水机微生物污染状况,为学生在校饮水卫生安全监督管理提供依据.方法 按GB/T 5750.12-2006《生活饮用水标准检验方法》检测菌落总数、总大肠菌群;按GB 4789.15-1998进行霉菌和酵母菌计数检测.结果 随机抽检112所学校336台饮水机出口水,细菌总数、总大肠菌群、霉菌和酵母菌合格率分别为29.17％、86.01％、60.12％.结论 学校饮水机饮用水微生物污染严重,小学尤其突出,应该引起有关部门高度重视.     

Chlordane contamination of a municipal water system

On March 24, 1976, a section of the public water system of Chattanooga, Tennessee, supplying 105 people was contaminated with chlordane, a chlorinated hydrocarbon pesticide. In a door-to-door health survey of the 71 residents affected, 13 (18%) were noted to have symptoms or signs compatible with mild acute chlordane toxicity. Serum levels of chlordane metabolites measured shortly after the incident did not correlate with the recorded symptomatology. Retesting of the symptomatic residents 2 months later revealed a possible rise in oxychlordane levels, suggestive of an acute exposure in the past. None of the residents have had prolonged sequelae from chlordane exposure; further followup is recommended.