Public health impacts of floods and chemical contamination

INTRODUCTION: Flooding accounts for about 40 per cent of all natural disasters that occur worldwide. In 2002-2003 many counties in England experienced severe floods. Floods are particularly important in public health terms as they may have multiple environmental consequences. METHODS: Details of floods reported to Chemical Hazards and Poisons Division, London [CHaPD(L)] were analysed and a literature review was undertaken to identify published reports of flood-related chemical incidents that have had an impact on public health. RESULTS: Epidemiological evidence shows that chemical material may contaminate homes and that in some cases flooding may lead to mobilization of dangerous chemicals from storage or remobilization of chemicals already in the environment, e.g. pesticides. Hazards may be greater when industrial or agricultural land adjoining residential land is affected. Less evidence exists to support the hypothesis that flooding that causes chemical contamination has a clear causal effect on the pattern of morbidity and mortality following these flooding events. CONCLUSION: In the light of this evidence, a checklist/pro forma for public health response to and investigation of flooding events that may result in chemical contamination was needed. This is available from CHaPD(L).     

High levels of faecal contamination in drinking groundwater and recreational water due to poor sanitation,in the sub-rural neighbourhoods of Kinshasa,Democratic Republic of the Congo

In many urban and peri-urban areas of developing countries, shallow wells and untreated water from urban rivers are used for domestic purposes, including drinking water supply, population bathing and irrigation for urban agriculture. The evaluation and monitoring of water quality are therefore necessary for preventing potential human risk associated with the exposure to contaminated water. In this study, physicochemical and bacteriological parameters were assessed in an urban river (named Kokolo Canal/Jerusalem River) draining the municipality of Lingwala (City of Kinshasa, Democratic Republic of the Congo) and in two shallow wells used as drinking water supplies, during the wet and dry seasons in order to estimate the seasonal variation of contamination. The faecal indicator bacteria (FIB) isolated strains (Escherichia coli (E. coli) and Enterococcus (ENT)) from water and surface sediment, were characterized for human-specific bacteroides by molecular approach. The results revealed very high faecal contamination of water from the shallow wells, and of water and sediments from the river, during both wet and dry seasons. During the wet season, E. coli reached the values of 18.6?×?10⁵ and 4.9?×?10⁵?CFU 100?mL^?1 in Kokolo Canal and shallow wells, respectively; and Enterococcus reached the values of 7.4?×?10⁴ and 2.7?×?10⁴?CFU 100?mL^?1. Strong mutually positive correlation was observed between E. coli and ENT, with the range of R-value being 0.93?<?r?<?0.97 (p-value?<?0.001, n?=?15). The PCR assays for human-specific Bacteroides indicated that more than 98% of 500 isolated FIB strains were of human origin, pointing out the effect of poor household sanitation practices on surface water but also on groundwater contamination. The water samples from the shallow wells and Kokolo Canal were highly polluted with faecal matter in both seasons. However, the pollution level was significantly higher during the wet season compared to the dry season. Physicochemical analysis revealed also very high water electrical conductivity, with values much higher than the recommended limits of the World Health Organization guideline for drinking water. These results highlight the potential human health risk associated with the exposure to water contamination from shallow wells and Kokolo Canal, due to the very high level of human FIB. Rapid, unplanned and uncontrolled population growth in the city of Kinshasa is increasing considerably the water demand, whereas there is a dramatic lack of appropriate sanitation and wastewater facilities, as well as of faecal sludge (and solid waste) management and treatment. The lack of hygiene and the practice of open defecation is leading to the degradation of water quality, consequently the persistence of waterborne diseases in the neighbourhoods of sub-rural municipalities, and there is a growing threat to the sustainability to water resources and water quality. The results of this study should encourage municipality policy and strategy on increasing the access to safely managed sanitation services; in order to better protect surface water and groundwater sources, and limit the proliferation of epidemics touching regularly the city.     

医用计算机鼠标、键盘细菌污染调查

目的 了解医用计算机的污染状况。方法 对某院20个科室使用的计算机鼠标、键盘进行物体表面采样及微生物调查、分析。结果 医用计算机染菌量严重超标,平均菌落数为114.1 CFU/cm~2。医生使用的计算机与护士使用的计算机污染程度差异有显著性(P<0.05)。金黄色葡萄球菌污染率较高,占30.5％。结论 计算机是医院内潜在的储菌源之一,我们在日常工作中应重视对其清洁消毒,以减少医院感染的危险因素。     

A water contamination incident in Oslo, Norway during October 2007; a basis for discussion of boil-water notices and the potential for post-treatment contamination of drinking water supplies

Over a 5 day period in October 2007 a boil-water notice was served on the majority of Oslo, capital city of Norway, as a result of a combination of bacteriological findings (coliforms, intestinal enterococci, and E. coli), and very low numbers of Cryptosporidium oocysts and Giardia cysts in 10 L water samples taken from the water distribution network. The water source had been regularly monitored for these parasites and generally found to be negative. Over 460,000 residents were affected by the boil-water notice, as were many thousands of businesses.     

Endogenous bacterial contamination of enteral tube feeding systems during administration of feeds to hospital patients

The use of sterile, prepackaged enteral feeds has helped to reduce the risk of exogenous microbial contamination of enteral feeds but there is increasing evidence that endogenous contamination with bacteria from the patient's own flora may occur. The purpose of this study was to compare the levels and types of micro-organisms present in residual feed in nutrient containers and giving sets when either 500 or 1000 ml prefilled, ready-to-hang nutrient containers were used to administer 1000 and 2000 ml quantities of feed to patients on hospital wards over 24 h using a single giving set over this period. Forty-one adult patients were randomly allocated to receive either 1000 or 2000 ml of sterile undiluted, whole protein feed over 24 h from 1000 ml prefilled containers (Nutrison Steriflo, Cow and Gate Nutricia Ltd) or from 500 ml prefilled bottles (Osmolite, Abbott Laboratories Ltd). One giving set was used over 24 h for each patient. Samples of feed from the nutrient containers and the distal end of each giving set were sent for microbiological analysis immediately after removal from the patient. Control experiments demonstrated that there were no micro-organisms in the unopened feed containers and that none was introduced during the feed sampling procedure. The percentage of days on which feed samples from the nutrient containers were contaminated was $lt; 10% for feeds administered at a rate of 1000 ml over 24 h and $lt; 23% for those administered at a rate of 2000 ml over 24 h irrespective of system, which may be attributed to increased handling of systems and reuse of the giving set. However, the percentage of days on which samples from the giving sets were contaminated was 43% for all systems. In fact, on an average of 33% of days it was found that the only feed sample that was contaminated was that collected from the giving set. Counts for these samples were $lt;10³ cfu/ml and the main bacteria isolated included Klebsiella spp., Enterobacter spp., Escherichia coli, Streptococcus faecalis and Pseudomonas aeruginosa. These results further implicate retrograde spread of the patient's own flora as a possible source of microbial contamination of feed in the giving sets of enteral feeding systems.     

Unintentional drinking-water contamination events of unknown origin: surrogate for terrorism preparedness

Drinking-water is a direct conduit to many human receptors. An intentional attack (e.g. terrorism) on drinking-water systems can shock and disrupt elements of national infrastructures. We report on an unintentional drinking-water contamination event that occurred in Tel Aviv, Israel in July, 2001. Initially of unknown origin, this event involved risk management strategies used by the Ministry of Health for abating a potential public health crisis as might be envisaged of water contamination due to terrorism. In an abrupt event of unknown origin, public health officials need to be responsible for the same level of preparedness and risk communication. This is emphasized by comparison of management strategies between the Tel Aviv event and one of dire consequences that occurred in Camelford, England in 1988. From the onset of the Tel Aviv incident, the public health strategy was to employ the precautionary principle by warning residents of the affected region to not drink tap water, even if boiled. This strategy was in contrast to an earlier crisis that occurred in Camelford, England in 1988. An outcome of this event was heightened awareness that a water crisis can occur in peacetime and not only in association with terrorism. No matter how minor the contamination event or short-term the disruption of delivery of safe drinking-water, psychological, medical and public health impact could be significant.     

江西省某大型超市自动扶梯扶手表面细菌污染特征分析

目的评估大型超市自动扶梯扶手表面细菌污染现状及影响因素,为提升公共卫生安全提供理论依据。方法于2017年8-10月分层随机抽取某大型超市内6个扶梯,以拭子涂抹法采集细菌并检测菌落总数,以16SrDNA测序技术及聚类分析检测微生物种类,以PCR扩增mecA基因及纸片扩散法(K-B法)检测耐药菌。结果扶梯人流量峰值2 h后,扶手表面菌落总数达到峰值,左、右扶手菌数无明显差异(P>0.05)。176份样品中,有50份样品细菌菌落总数高于10CFU/cm^2(占28.4%),8份样品高于100 CFU/cm^2(占4.5%)。6份样品mecA基因检测呈阳性(占3.4%)。扶手表面检出19株菌,属于4门5纲(芽孢杆菌纲、α-变形菌纲、β-变形菌纲、放线菌纲、散囊菌纲)7属共12种菌株,其中芽孢杆菌纲占50%(6/12),α变形菌纲占25%(3/12),并检出条件性致病微生物蜡样芽孢杆菌和黄曲霉菌。在检出的6株葡萄球菌中,有3株携带mecA基因,并对青霉素、头孢曲松耐药,对氧氟沙星敏感。结论大型超市扶梯扶手表面微生物物种丰富,存在细菌包括耐药葡萄球菌污染,扶手表面污染程度受人流量影响,提示大型超市扶梯扶手存在致病菌传播的潜在风险。     

Bacterial contamination in a modern operating suite. 3. Importance of floor contamination as a source of airborne bacteria.

The redispersal factor for bacteria-carrying particles from a contaminated floor was determined after mopping, blowing and walking activity. Walking gave the highest redispersal factor, 3.5 X 10(-3) m-1, which was three times higher than for blowing and 17 times higher than for mopping. The mean die-away rate for the bacteria-carrying particles used was 1.9/h without ventilation and 14.3/h with ventilation. It was calculated that in the operating rooms less than 15% of the bacteria found in the air were redispersed floor bacteria.     

Microbial contamination in vegetables due to irrigation with partially treated municipal wastewater in a tropical city

A total of 144 samples of water used for irrigation were collected from Dinapur, DLW sewage treatment plant and river water of Ganga at Rajghat and 258 irrigated vegetable samples were collected from nearby agricultural fields in the close vicinity of three treatment plants and examined using standard procedures for coliform and viable counts and the presence of Escherichia coli, Salmonella, Clostridium and Vibrio during the winter and rainy seasons. Irrigation water from Rajghat drain had significantly higher coliform counts by location and season than the water from the Dinapur and DLW. Although all the vegetables had coliform counts higher than the recommended standard (range 3.40 - 6.38 log10 cfuml(-1)), spinach and cabbage had significantly higher (p < 0.05) counts compared to other vegetables during the dry season. Salmonella was significantly more likely to be detected during the rainy season than during the dry season. Contaminated vegetable intake may pose a serious threat to human health.     

医用可控防辐射门的设计与应用

目的防止X射线泄漏,减少疾病接触传播,防止交叉感染。方法用PLC配合红外线传感器多位检测,控制防辐射门。结果防止人员误入正在曝光的机房,有效控制了X射线泄漏,使原有手动推拉防辐射门成为全自动可控式。结论该门起到了很好的防辐射作用。自动开关门减少了工作人员开关门的烦琐工作,防止疾病的接触传播,减少了院内感染的发生。     

中国七类食品中单核细胞增生性李斯特氏菌污染状况调查

于１９９６～１９９７年组织了全国１２个省,对国内七类食品３７４６份样品进行单核细胞增生性李斯特氏菌（Ｌｉｓｔｅｒｉａｍｏｎｏｃｙｔｏｇｅｎｅｓ简称ＬＭ）的污染调查,结果表明：七类样品中除蔬菜外均检出了致病单核细胞增生性李斯特氏菌。其分离率为：冷饮１．３９％、生肉１．５３％、乳制品０．５２％、熟肉制品０．４７％、乳０．７２％及水产品０．１９％。表明ＬＭ在我国食品中存在污染,有食物中毒的潜在危险。     

Enteral feeding tube guidewire—another factor in the retrograde contamination of enteral feeding systems?

Background: In vitro enteral feeding systems were used to investigate the effect that withdrawal of the guidewire from the feeding tube has on bacteria ascending from a patients’ stomach or intestine via the feeding tube to the giving set and nutrient container of the feeding system. Methods: Enteral feeding systems were assembled with the feeding tube running into nutrient broth contaminated with Klebsiella aerogenes. The enteral feeding tubes were held in different orientations (horizontal and vertical) to examine the effect in both prostrate and ambulant patients. The guidewire was removed either prior to or after the enteral feeding tube had been inserted into the K. aerogenes broth. Feed was then run through the systems for 24 h, with feed samples being collected from the distal (patient) end of the giving set at 0 and 24 h. Results: After 24 h, 10^3–108 c.f.u. (colony forming units) K. aerogenes/ml were detected in feed samples taken from the distal end of the giving set in systems where the guidewire had been removed after the enteral feeding tube had been inserted into the contaminated broth (both orientations), but K. aerogenes was not detected in samples from systems in which the guidewire had been removed before the end of the tube was inserted into the broth (both orientations). However, when the latter feed samples were enriched (i.e. incubated at 37 °C for a further 24 h to detect if very low levels of bacteria were present in the original sample), 40% of samples from systems with horizontally orientated tubes, and 20% from systems with vertically orientated tubes were positive for the test organism. K. aerogenes was not detected in any samples of feed taken from the nutrient container or just below the drip chamber. Conclusion: The results demonstrate: (i) that bacteria ascend the feeding tube over a 24-h period (retrograde contamination) and (ii) removal of the guidewire can contribute to the colonization of the lumen of the feeding tube and distal end of the giving set with bacteria from a patients’ own flora.     

实验动物垫料的微生物污染监测及影响因素研究

目的对实验动物垫料进行微生物指标监测,为管理机构制定垫料的卫生标准提供依据,为垫料生产企业在加工、灭菌、包装、运输、储存等环节及动物使用单位对动物实验结果影响因素分析方面提供参考依据。方法对来自不同实验动物生产和使用单位的垫料,参照GB4789-2010、2012检测方法进行菌落总数、霉菌及大肠杆菌计数、沙门菌的检测。结果 49份未灭菌的垫料存在不同程度的细菌、霉菌及大肠杆菌污染,未检出沙门菌;不同材质的垫料在不同条件下灭菌,在121℃30 min的条件下具有最佳灭菌效果,各项微生物指标均合格;已灭菌的21份垫料有19份存在不同程度的细菌及霉菌污染,未检出沙门菌及大肠杆菌;松软的混合型刨花垫料在灭菌后7 d检测到细菌;采用敞开编织袋储存5 d即检测到细菌污染;垫料使用1 d后的菌量可达104CFU/g,细菌及霉菌含菌量按天数逐步递增,但未检出沙门菌。结论垫料使用前必须消毒灭菌,采用合理的方式储存,及时更换可改善饲养环境,可减少微生物污染,保障实验动物的质量及实验结果的可靠。     

Evaluation of environmental bacterial contamination and procedures to control cross infection in a sample of Italian dental surgeries

OBJECTIVES—To perform a pilot study on bacterial contamination in some dental surgeries (n=51) in a local health unit in Brescia (Lombardy Region, Italy) and to evaluate the procedures to control cross infection used by the personnel to reduce the risk of infection in dental practice.
METHODS—A survey was carried out by interviewing 133 dental personnel with a questionnaire on the procedures used to control infection. The autoclaves, chemical baths (chemiclaves), and ovens present in the surgeries were tested for sterilisation efficiency with a spore test, and already packed and sterilised instruments were randomly sampled and tested for sterility. Microbial contamination of air, surface, and dental unit water samples were also studied.
RESULTS—The dental personnel did not generally follow the principal procedures for infection control: 30% of personnel were not vaccinated against hepatitis B virus, infected instruments were often not decontaminated, periodic checks of autoclave efficiency were lacking, and the knowledge of disinfection mechanisms and procedures was incomplete. High bacteriological contamination of water at dental surgeries was often found and total bacteriological counts in air samples were high. Surface studies showed widespread bacterial contamination.
CONCLUSIONS—On the basis of these results, an educational programme for the prevention of infective hazards has been prepared and carried out. The results of this pilot study will be used for planning a national survey.


Keywords: dental surgeries; bacterial contamination; cross infection control procedures     

2003～2008年山东省流通领域食品沙门氏菌污染状况调查

目的了解山东省流通领域食品沙门氏菌污染状况。方法2003～2008年夏秋季,在山东省部分地区的集贸市场、超市采样检测。结果2003～2008年,合计检测各种食品1 681份,检出沙门氏菌的49份,检出率为2.91%。沙门氏菌检出率:生鸡肉为6.47%,生羊肉为1.58%,生牛肉为2.35%,生猪肉为6.25%,散装熟肉为0.30%,生食蔬菜未检出(P<0.01);2003年为2.31%,2004年为3.30%,2005年为2.34%,2006年为1.76%,2007年为3.57%,2008年为6.15%(P>0.05);济南市为5.04%,烟台市为1.6%,菏泽市为1.59%,莱芜市为2.17%,德州市为2.37%,潍坊市为2.33%(P>0.01)。结论山东省部分地区集贸市场食品摊点销售的食品沙门氏菌污染较为严重,尤以肉及肉制品明显。     

Bacterial contamination of enteral feeding systems due to faulty handling procedures—a comparison of a new system with two established systems

Background: The purpose of this study was to compare the risks of introducing microbial contamination when assembling and running two commonly used, ready-to-hang, enteral feeding systems (Nutrison glass bottles and Steriflo) with a newly introduced system (Nutrison pack). Methods: The nutrient container tops of all systems were deliberately touched during assembly by a researcher wearing gloves contaminated with Klebsiella aerogenes. After touching, half the containers were immediately connected to giving sets, the other half were disinfected using alcohol wipes before connection to the giving sets. Systems were run for 24 h, with a change of nutrient container at 12 h for the Steriflo (2×1000 ml), Nutrison pack (2×1000 ml) and Nutrison glass bottles (2×500 ml), and at 6 h for the Nutrison glass bottles (4×500 ml). Feed samples for microbiological analysis were taken from feed in the systems at the 0 h assembly, and from residual feed in all discarded nutrient containers. Each protocol was repeated five times. Results: The percentage of feed samples in which K. aerogenes was detected reduced significantly from 68% for non-disinfected Nutrison glass bottles changed every 6 h, to 59% after disinfection, and from 51% to 0% after disinfection of Steriflo systems (Mann–Whitney, P< 0.05). For Nutrison glass bottles changed every 12 h the fall from 51% with no disinfection to 49% after disinfection was not significant (Mann–Whitney, P< 0.05). Nutrison packs were not disinfected and yet K. aerogenes was only detected in 2% of feed samples. This rate of contamination was significantly less than that for all the other non-disinfected systems (Mann–Whitney, P< 0.05). Conclusion: The results show a reduction in the incidence of bacterial contamination of the feed samples when systems were disinfected subsequent to being exposed to faulty handling procedures, thus supporting manufacturers recommendations to disinfect systems during assembly. The results particularly highlight the important role played by system design in reducing the levels and incidence of bacterial contamination of enteral tube feeds.     

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.