The Occurrence and Viability of Giardia Cysts in Scottish Raw and Final Waters |
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| Authors: | H V SMITH PhD LUCY J ROBERTSON PhD R A GILMOUR BSc PhD MRIEHIS G P MORRIS BSc MRIEHIS R W A GIRDWOOD FRCPath P G SMITH BSc MSc PhD |
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| Affiliation: | Scottish Parasite Diagnostic Laboratory, Stobhill General Hospital, Glasgow.;Division of Environmental Health, University of Strathclyde, Glasgow.;Now at: Water &Environmental Management Unit, University of Strathclyde, Glasgow. |
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| Abstract: | The occurrence of Giardia cysts in Scottish raw and potable waters was investigated. Giardia cysts were detected in 49% of raw waters, with concentrations of up to 1.05 cysts per litre, and in 19% of final waters, with concentrations of up to 1.67 cysts per litre. In some of the positive water samples the viability of the cysts was assessed by viewing the cyst morphology and inclusion/exclusion of propidium iodide. Viable cysts were detected in a proportion of both raw waters and positive final waters studied. Further investigations at 21 water-treatment plants revealed cysts in 9 (43%) of the raw waters, and in 4 (19%) of the final waters. Cysts were only detected in the final waters of plants in which cysts were also detected in the raw water. These data indicate that viable Giardia cysts may be ingested with potable water in Scotland. |
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| Keywords: | Cysts Giardia viability water treatment |
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