Page 15: Guidelines for Canadian Drinking Water Quality: Guideline Technical Document - Enteric Protozoa: Giardia and Cryptosporidium

Appendix E:

Selected Table 1 Footnote a Giardia and Cryptosporidium outbreaks related to public, semi-public and private drinking water systems in Canada (1977-2001)
Date Location Causative agent Scope of outbreak Attributable causes References
Mar 20 - Apr 26, 2001 North Battleford, SK Cryptosporidium 25 laboratory confirmed; 5,800 - 7,100 people estimated to have been affected 
  • vulnerability of the North Battleford River to contamination by Cryptosporidium in runoff (i.e., drinking water intake only 3.5 km downsteam of the treated sewage outfall)
  • poor treatment performance (including ineffective turbidity removal)
Stirling et al.,  2001
Jun 2 - Jul 12, 1996 Cranbrook, BC Cryptosporidium 29 laboratory-confirmed; 107 clinical; estimated 2,000 cases
  • livestock manure contamination of the unfiltered, chlorinated water supply
BCCDC, 1996
Ong et al., 1997, 1999
Feb - May, 1994 Temagami, ON Giardia 26 laboratory-confirmed; between 160 and 330 clinical
  • contamination from human sewage, due to premature thaw in February, and waste management problems
  • contamination from beaver
  • poor filtration performance
  • inadequate chlorine disinfection
Wallis et al., 1998
Feb - May, 1993 Kitchener-Waterloo, ON Cryptosporidium 143 laboratory-confirmed *Note: No epidemiological evidence reported to establish association with drinking water
  • spring run-off (increased turbidity)
  • recycling filter backwash supernatant to the filters (concentrated oocysts from raw water); challenged fine-particle removal in the treatment process
Pett et al., 1993
Welker et al., 1994
Jan - Apr, 1990 Creston & Erikson, BC Giardia 124 laboratory-confirmed
  • unfiltered, unchlorinated surface water
  • beavers excreting large numbers of Giardia cysts into water supply
Isaac-Renton et al., 1993, 1994
Jun - Aug, Nov, 1986 Penticton, BC Giardia 362 laboratory-confirmed 3,100 estimates cases 
  • unfiltered surface water supply using only chlorine for inactivation of Giardia
Moorehead et al., 1990
Nov -  Dec, 1985 Creston, BC Giardia 83 laboratory-confirmed
  • unfiltered, unchlorinated surface water
Isaac-Renton et al., 1993

Table 1 Footnotes

Table 1 Footnote 1

These represent well-documented outbreaks.

Return to Table 1 footnote a referrer

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