A fifteen-month fortnightly survey of microbial health risk indicators and pathogens has been carried out at 25 freshwater recreational and water supply sites distributed throughout New Zealand, for: E. coli, Clostridium perfringens spores, F-RNA bacteriophage, somatic coliphage, human enteroviruses, human adenoviruses, Cryptosporidium oocysts, Giardia cysts, Salmonella and Campylobacter. Sites were selected to represent five geographical areas covering New Zealand and five categories of predominant environmental impact: birds, dairy farming, forestry/undeveloped, municipal, and sheep/pastoral farming. Six of the sites were also source waters for treated drinking-water supplies. Of the indicators, E. coli was detected in 99 % of all samples, with somatic coliphage being detected most of the time (89 %). Of the pathogens tested, Campylobacter and human adenoviruses were inferred to be the most likely to cause human waterborne illness to recreational freshwater users. Using data from all sites, an estimated 5 % of notified campylobacteriosis cases in New Zealand could be attributable to water contact recreation. The critical value for E.coli as an indicator of increased Campylobacter infection is in the range of 200–500 E. coli per 100 ml. This result has been used to derive new national water quality guidelines for recreational fresh water in New Zealand.
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Research Article|
March 01 2008
Large-scale freshwater microbiological study: rationale, results and risks
Desmond Till;
1Public Health Microbiology Consultant, 5 Maire Street, Eastbourne, Wellington, New Zealand
Tel.: +64 (0)4 562 7122 Fax: +64 (0)4 562 0134 E-mail: [email protected]
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Graham McBride;
Graham McBride
2National Institute of Water and Atmospheric Research (NIWA), P.O. Box 11-115, Hamilton, New Zealand
Tel.: +64 (0)7 856 1726 Fax: +64 (0)7 856 0151 E-mail: [email protected]
Tel.: +64 (0)7 856 1726 Fax: +64 (0)7 856 0151 E-mail: [email protected]
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Andrew Ball;
Andrew Ball
3Institute of Environmental Science and Research (ESR), P.O. Box 29-181, Christchurch, New Zealand
Tel.: +64 (0)3 351 6019 Fax: +64 (0)3 351 0010 E-mail: [email protected]
Tel.: +64 (0)3 351 6019 Fax: +64 (0)3 351 0010 E-mail: [email protected]
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Ken Taylor;
Ken Taylor
4Environment Canterbury, P.O. Box 345, Christchurch, New Zealand
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Eric Pyle
Eric Pyle
5Ministry of Research, Science and Technology, P.O. Box 5336, Wellington, New Zealand
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J Water Health (2008) 6 (4): 443–460.
Article history
Received:
April 20 2007
Accepted:
December 02 2007
Citation
Desmond Till, Graham McBride, Andrew Ball, Ken Taylor, Eric Pyle; Large-scale freshwater microbiological study: rationale, results and risks. J Water Health 1 December 2008; 6 (4): 443–460. doi: https://doi.org/10.2166/wh.2008.071
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