Vorkommen von <i>Campylobacter</i> spp. in Oberflächengewässern : Eintragspfade, Nutzungskonflikte und Gesundheitsgefährdung

Campylobacterinfektionen sind weltweit verbreitet und weisen in Deutschland die höchste Inzidenz der bakteriellen Gastroenteritiden auf. Als Infektionsquelle ist neben Lebensmitteln auch Wasser zu nennen, dessen Bedeutung als Übertragungsweg noch unvollständig erfasst ist. Durch die vorliegende Arbeit konnten Daten zum Vorkommen von Campylobacter in Oberflächengewässern mit unterschiedlich strukturierten Einzugsgebieten der gemäßigten Breiten gewonnnen werden. Neben dem Einfluss der im Einzugsgebiet vorhandenen Flächennutzung auf das Vorkommen von Campylobactern wurde auch das Eintragspotential verschiedener Kläranlagentypen bestimmt. Daneben fanden ereignisbezogene Probenahmen an Regenentlastungsbauwerken statt. Die mikrobiologischen Untersuchungen umfassten primär den Parameter Campylobacter und verschiedene hygienisch-mikrobiologische Indikatorparameter, sowie chemisch-physikalische Kenngrößen. Die Campylobacterkonzentrationen wurden semiquantitativ mittels Flüssigkeitsanreicherung ermittelt. Die Campylobacterkonzentrationen im Gewässer sind abhängig von der Nutzung des Einzugsgebietes. Die höchsten Konzentrationen traten, auf, wenn das Gewässer als Vorfluter für Kläranlagen dient. Die Art der Kläranlagentechnik bestimmt die Reduktionsleistung, sodass Kompaktkläranlagen im Normalbetrieb einen wichtigeren Eintragspfad für Campylobacter darstellen als mehrstufige Kläranlagen. Kläranlagen liefern besonders bei Trockenwetter bis zu zwei Drittel des Gewässervolumens, wobei die aus ihnen stammende Camplyobacterfracht 20 % der Gewässerfracht ausmacht. Mischwasserabschlägen tragen hingegen zu 42 % zur Campylobacterfracht im Gewässer bei und stellen somit den größten Eintragspfad einer Punktquelle dar, der allerdings das geringste Wasservolumen besitzt. Nutzungskonflikte ergeben sich bei der direkten Nutzung des Gewässers zur Trinkwassergewinnung, als Badegewässer, Tränke und Bewässerungswasser. Die Anwendung bestehender gesetzlicher Regelungen scheinen jedoch geeignet zu sein, das Risiko einer Campylobacterinfektion über Trink- und Badewasser zu minimieren. Dies gilt auch für die Wasserverwendung in der Landwirtschaft, wobei intensivere Kontrollen und weitere Untersuchungen nötig wären, um das tatsächliche Infektionsrisiko für den Menschen genauer bestimmen zu können. Ein besonderes Risiko leitet sich aus der hohen Campylobacterfracht während Regenereignissen ab. Campylobacter können im Gewässer über längere Distanzen transportiert werden und somit in Gebiete gelangen, in denen kein Regenereignis auftrat. In diesen Gebieten findet weiterhin eine uneingeschränkte Gewässernutzung statt und es entsteht in diesem Fall aus allen Nutzungsarten ein akutes Gesundheitsrisiko. Alle Maßnahmen, die den Eintrag von Fäkalien in Gewässer minimieren, reduzieren auch den Eintrag von Campylobacter und senken damit das potentielle Gesundheitsrisiko. Insbesondere Mischwasserabschläge, die einen sehr großen Anteil an der Campylobacterfracht haben, bieten aufgrund des geringen Volumens Ansatzpunkte für eine weitergehende Behandlung und es könnte durch diese eine Frachtreduktion erreicht werden. In Zukunft sollten Abwasserbehandlungsanlagen auch unter Berücksichtigung der Reduktion von hygienisch-mikrobiologischen Parametern, wie Campylobacter, geplant und bewertet werden, um die Infektionsrisiken für die öffentliche Gesundheit weiter zu reduzieren.Sources of Campylobacter spp. in surface water - pathways, conflicts of interest, health risks Infections due to Campylobacter occur world-wide. In Germany, they are the most significant causative agent of bacterial gastro-enteritis. Aside from food, water is also a source of infection, but the importance of water as a transmission path is not yet fully understood. For this thesis, data about the occurrence of Campylobacter in surface water with differently structured catchments in the temperate zone were generated. In four different catchments the influence of land use on Campylobacter concentrations was analysed, as was the impact potential of different sewage treatment plant types. Additionally, sampling of combined sewer overflow during rain events was undertaken. Primarily, the microbiological analysis covered Campylobacter and also different hygienic-microbiological indicator parameters, chemicals and physical characteristics. To determine the Campylobacter concentrations a semi-quantitative liquid enrichment method was used. It could be shown that the Campylobacter concentrations in the watercourse were dependent on the land use in the catchment. The highest concentrations were found in receiving watercourses for treated sewage. The reduction efficacy of the sewage plants depends on their design. Under regular operating conditions, simple, compact plants are of greater importance as a source of Campylobacter than are highly sophisticated treatment plants. Especially during dry weather conditions, sewage treatment plants discharged up to two-thirds of the river water volume, while 20 % of the Campylobacter load found in the watercourse was due to treated sewage discharge. If combined sewer overflow occurs, it accounts for 42% of the Campylobacter load in the watercourse and is therefore the most important point source for Campylobacter in the water, even though combined sewer overflow accounts for the smallest water contribution to the watercourse. Conflicts of interest result from the direct use of watercourses for the drinking water supply, as bathing water, for watering animals, as irrigation water and as recipients of treated sewage water. Existing legislation seems to be adequate to minimise the risk of drinking water or bathing water-related Campylobacter infections. This is also true for water used in agriculture, but here more intensive controls and further investigation would be necessary to determine the true risk of infection for human beings. A specific risk can be derived from the high Campylobacter load as a result of rain events. The transport of Campylobacter over long distances in the watercourse brings them to areas where no rain event has occurred. Here, unrestricted use of the water course can take place and in this case all forms of water usage pose an immediate health risk. All actions to minimise the entry of faecal matter into watercourses will minimise the influx of Campylobacter and as a result, also reduce potential health risks. In particular, combined sewer overflow with its small volume and high impact on the occurrence of Campylobacter in the watercourse provides points where further treatment could achieve a reduction of the load. In the future, the planning and evaluation of sewage treatment plants should also consider the reduction of hygienic-microbiological parameters like Campylobacter, in order to achieve a further reduction of the risk of infection for public health

Mass balance of nitrogen and potassium in urban groundwater in Central Africa, Yaounde/Cameroon

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Local search: A guide for the information retrieval practitioner

There are a number of combinatorial optimisation problems in information retrieval in which the use of local search methods are worthwhile. The purpose of this paper is to show how local search can be used to solve some well known tasks in information retrieval (IR), how previous research in the field is piecemeal, bereft of a structure and methodologically flawed, and to suggest more rigorous ways of applying local search methods to solve IR problems. We provide a query based taxonomy for analysing the use of local search in IR tasks and an overview of issues such as fitness functions, statistical significance and test collections when conducting experiments on combinatorial optimisation problems. The paper gives a guide on the pitfalls and problems for IR practitioners who wish to use local search to solve their research issues, and gives practical advice on the use of such methods. The query based taxonomy is a novel structure which can be used by the IR practitioner in order to examine the use of local search in IR

Water, sanitation and hygiene in wetlands: A case study from the Ewaso Narok Swamp, Kenya

Wetlands can be both a blessing and a curse. They are beneficial sources of safe water and nutrition and places from which humans derive their livelihoods. At the same time, wetlands are known to be sources of disease-causing microorganisms and invertebrates that can threaten human health. Safe water, sanitation and personal hygiene (WASH) are crucial preconditions for the prevention of disease transmission. And of special importance for people living in wetlands, depending on and being exposed to them. WASH should be prioritized especially in those wetlands that are subject to intensive use, that have a poor sanitation infrastructure, and which at the same time only provide limited water resources. However, despite this critical importance, WASH in wetlands is not well characterized in literature. This study therefore aimed at providing insights into the water, sanitation and hygiene conditions and behavioural determinants of households in wetlands by presenting the case of a rural wetland in East Africa. The mixed method approach included a broad set of empirical data collected during a household survey (n = 400), an observational WASH assessment (n = 397) and in-depth interviews (n = 20) conducted from January to March 2015 in Ewaso Narok Swamp in Kenya. Different user groups of the wetland were targeted. The study in Ewaso Narok Swamp showed that wetland users’ water supply and storage, sanitation and personal hygiene conditions were inadequate for large parts of the community and significantly differed between groups. Whereas the WASH conditions of people working in the service sector were rather positive, for pastoralists, they were correspondingly negative. The WASH behaviour was also perceived to be inadequate influenced by a variety of determining factors. The observational index as applied in this study indicated to be a valuable, rapid and efficient tool for assessing domestic WASH and for detecting differences between different groups in wetlands. Combined with the quantitative and qualitative data, the approach served as a very helpful model to develop a multi-layered understanding of WASH conditions and related behaviour. The people in the researched wetland use by far less improved water sources and sanitation facilities than the nationwide average for rural populations. Since Ewaso Narok Swamp serves as a model case for the domestic WASH conditions in a rural wetland in semiarid East Africa, this fact make the study relevant not only at a national, but also at an international level. The results underline the previously formulated need of an integrative approach that first and foremost complements wetland management by public health interventions. In order to improve WASH conditions and to change behaviour in the long term, interventions should include the provision of clean water and sanitation infrastructure, as well as widespread health education. The approach proved to be useful for wetland environments and will be integrated into the development of a health impact assessment tool for wetlands. Moreover, it can be adopted in other contexts

Contracting infectious diseases in Sub-Saharan African wetlands: A question of use? A review

Worldwide the pressure on water is increasing. In parts of Sub-Saharan Africa (SSA), natural wetlands constitute the only accessible water resources, providing water free of charge, agricultural potential and livelihoods in otherwise uninhabitable landscapes, which is why they are being used extensively. The degradation and contamination of water which result from the use of wetlands has the potential to spread disease-causing microorganisms and provide increased breeding habitats for disease vectors, Despite this importance, case studies are lacking and knowledge gaps remain about whether and how different kinds of wetland use influence the exposure to health risks and transmission of infectious diseases. This descriptive literature review aimed at identifying publications from peer-reviewed journals and book chapters that (i) address water-related infectious diseases in SSA wetlands and (ii) link those diseases to use-related exposures. The resulting overview includes 27 publications and shows that depending on the type of use, people in wetlands are exposed to different risk factors and water-related infectious diseases. Exposure to infectious agents depends on occupational characteristics, and time spent in wetlands. Disease transmission is driven by users’ contact to water, characteristics of pathogens and vectors of disease. The amount of available literature varies significantly. Whereas several publications have linked crop production and the domestic use of wetland water to contraction of diseases, fewer are available on health risks identified with pastoralism in wetlands and other uses. Some risk factors are well researched, such as irrigation schemes favouring schistosomiasis prevalence. For others, including proximity of pastoralists to their livestock and the associated trachoma risk, knowledge remains limited. This review establishes connections of selected diseases with different transmission pathways that are linked to specific risk factors, transmission pathways and resulting diseases. All of these have been integrated into a detailed conceptual framework which simplifies the complexity of the relationships, while at the same time identifying missing links which might provide stimulus for future research tackling the potential research gaps. It concludes that socio-cultural and behavioural considerations regarding the wetland users are not sufficiently evaluated and should receive increased attention in future investigations

Effects of local and spatial conditions on the quality of harvested rainwater in the Mekong Delta, Vietnam

The objective of this study was to assess the quality of harvested rainwater in the Mekong Delta (MD), Vietnam for local (roof types, storage system and duration) and spatial (proximity of industry, main roads, coastline) conditions. 78 harvested rainwater samples were collected in the MD and analyzed for pH, turbidity, TDS, COD, nutrients (NH4, NO3, NO2, o-PO4), trace metals and coliforms. The results show that thatch roofs lead to an increase of pollutants like COD (max 23.2 mgl−1) and turbidity (max 10.1 mgl−1) whereas galvanized roofs lead to an increase of Zn (max 2.2 mgl−1). The other local and spatial parameters had no or only minor influence on the quality of household harvested rainwater. However, lead (Pb) (max. 16.9 μgl−1) and total coliforms (max. 102 500 CFU100 ml−1) were recorded at high concentrations, probably due to a variety of household-specific conditions such as rainwater storage, collection and handling practices

Chapter 7: Data management and analysis using GIS

Kistemann T, Queste A, Wienand I, Claßen T. Chapter 7: Data management and analysis using GIS. In: Funari E, Kistemann T, Herbst S, Rechenburg A, eds. Technical guidance on water-related disease surveillance. Kopenhagen: World Health Organization; 2011: 102-110