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Giardiasis outbreak from a chlorinated community water supply
W P Moorehead1, R Guasparini, C A Donovan
1South Okanagan Health Unit, Kelowna, BC.
Canadian Journal of Public Health = Revue Canadienne De Sante Publique
|September 1, 1990
Summary
A 1986 giardiasis outbreak in Penticton, British Columbia, infected over 12% of the population. Beaver-contaminated surface water was the source, highlighting the need for improved water treatment to prevent future outbreaks.
Area of Science:
- Environmental Health
- Epidemiology
- Waterborne Diseases
Background:
- A significant giardiasis outbreak occurred in Penticton, British Columbia, in 1986.
- The outbreak was linked to a chlorinated, unfiltered surface water supply.
Purpose of the Study:
- To identify the source of the giardiasis outbreak.
- To estimate the attack rate and physician visit burden.
- To confirm the water source's role and explore prevention strategies.
Main Methods:
- Telephone survey to estimate attack rates.
- Case-control study to identify risk factors.
- Retrospective physician record survey for epidemic curve analysis.
Main Results:
- 362 laboratory-confirmed cases and an estimated 12% attack rate.
- A reservoir pond with Giardia-infected beaver implicated as the source.
- A second outbreak confirmed the water source's culpability despite reservoir improvements.
Conclusions:
- The unfiltered surface water supply was the definitive source of the giardiasis outbreak.
- Enhanced water treatment is crucial to mitigate risks of future outbreaks.
- Ongoing exploration of water safety measures is necessary.