Analysis of dissemination of waterborne pathogens from raw water and related health issues in Sweden using GIS
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Water-related diseases are a major issue of public health worldwide. Raw drinking water retrieved from surface and groundwater undergoes treatment at water treatment plants in order to disable certain microorganisms that if were to be released in drinking water, would cause a variety of unwanted gastrointestinal symptoms. As such, it is imperative that research goes in the direction of preventing the entry of such microorganisms in drinking water by identifying potential risk situations involving high concentrations in raw water.
The objective of this thesis research is to examine variations and peaks in concentrations of notable pathogens found in raw water samples retrieved from the influx of five different water treatment facilities in Sweden, along with visualisations of related health symptoms that might have been the result of pathogen contamination in areas that were supplied by those waterworks. The primary source for the raw water data is Folkhälsomyndigheten (Public Health Agency of Sweden) and covers the period of March 2014 to 2015 in an ongoing project, however data from before this project started have also been retrieved from Vattentäktsarkivet covering the period of 2009-2013 for the representative waterworks. The data used to visualise the related health symptoms were retrieved from Healthcare Guide 1177, based on telephone triage. Along with that data, SCB data on population were used along with a shapefile of postal areas of Sweden, provided by Postnummerservice.
In order to visualise symptoms across time and to examine possible rises of symptoms related to gastrointestinal diseases across the period of analysis, Excel and Geographical Information System (GIS) toolboxes Spatial Analyst and Data Management were used in order to process the data from 1177, create time-animated outputs that depicted the symptoms monthly for every area and to identify areas that reported the most symptoms using density maps and hot-spot analysis. Statistical analysis and graphs for the data regarding the raw water dataset were performed in Excel.
The results implied minor correlations between high concentrations of notable pathogens in raw water and a rise of symptoms reported to 1177 in some months and areas during the period of analysis. The suspect months and areas were identified through a visualisation of clusters of symptoms and increases in comparison to normal seasonal effects. The winter months along with March and April generally showed the highest number of reported symptoms in all counties and a comparison of incidence rates revealed that the municipalities of Östersund and Trollhättan had the highest incidence rates in regards to their population.
A large source of error in the analysis is the raw water dataset itself. Since raw water always undergoes treatment, it is typically assumed that pathogens are removed prior to entering drinking water. It is possible that pathogens might elude this process, though it is difficult to exclude other sources of infection, such as contaminated food or seasonal contagious effects like winter-vomiting disease without access to patient records.
Place, publisher, year, edition, pages
2015. , 99 p.
TRITA-GIT EX, 15-007
GIS, water, pathogens
IdentifiersURN: urn:nbn:se:kth:diva-170381OAI: oai:DiVA.org:kth-170381DiVA: diva2:828123
Subject / course
Master of Science - Transport and Geoinformation Technology
Ban, Yifang, ProfessorSkog, Lars
Ban, Yifang, Professor