Prevention and containment of outbreaks requires examination of the contribution and interrelation of outbreak causative events. An outbreak fault tree was developed and applied to 61 enteric outbreaks related to public drinking water supplies in the EU. A mean of 3.25 causative events per outbreak were identified; each event was assigned a score based on percentage contribution per outbreak. Source and treatment system causative events often occurred concurrently (in 34 outbreaks). Distribution system causative events occurred less frequently (19 outbreaks) but were often solitary events contributing heavily towards the outbreak (a mean % score of 87.42). Livestock and rainfall in the catchment with no/inadequate filtration of water sources contributed concurrently to 11 of 31 Cryptosporidium outbreaks. Of the 23 protozoan outbreaks experiencing at least one treatment causative event, 90% of these events were filtration deficiencies; by contrast, for bacterial, viral, gastroenteritis and mixed pathogen outbreaks, 75% of treatment events were disinfection deficiencies. Roughly equal numbers of groundwater and surface water outbreaks experienced at least one treatment causative event (18 and 17 outbreaks, respectively). Retrospective analysis of multiple outbreaks of enteric disease can be used to inform outbreak investigations, facilitate corrective measures, and further develop multi-barrier approaches.
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Research Article|
September 01 2007
Fault tree analysis of the causes of waterborne outbreaks
Helen L. Risebro;
1School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK
Tel.: +44 1603 591004 Fax: +44 1603 593752; E-mail: [email protected]
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Miguel F. Doria;
Miguel F. Doria
2UNESCO/International Hydrological Programme (IHP), 1 rue Miollis, F-75732, Paris Cedex 15 France
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Yvonne Andersson;
Yvonne Andersson
3Swedish Institute for Infectious Disease Control (SMI), SE-17182 Solna, Sweden
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Gertjan Medema;
Gertjan Medema
4Kiwa Water Research, PO Box 1072, 3430 BB, Nieuwegein, The Netherlands
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Keith Osborn;
Keith Osborn
5United Utilities Water PLC, Thirlmere House, Lingley Mere Business Park, Greta Sankey, Warrington WA5 3LP, UK
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Olivier Schlosser;
Olivier Schlosser
6Suez Environnement/CIRSEE, Water Quality Technical & Research Division, 38 rue du Président Wilson, F78230 Le Pecq, France
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Paul R. Hunter
Paul R. Hunter
1School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK
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J Water Health (2007) 5 (S1): 1–18.
Citation
Helen L. Risebro, Miguel F. Doria, Yvonne Andersson, Gertjan Medema, Keith Osborn, Olivier Schlosser, Paul R. Hunter; Fault tree analysis of the causes of waterborne outbreaks. J Water Health 1 September 2007; 5 (S1): 1–18. doi: https://doi.org/10.2166/wh.2007.136
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