Abstracts - Posters
A Possible Role of High Impact Weather Events in Waterborne Disease Outbreaks in Canada, 1975-2001
M. Kate Thomas1 and Dominique F. Charron
1Public Health Agency of Canada
Kate_Thomas@phac-aspc.gc.ca
Background:
An adequate supply of safe water is crucial to health and wellbeing. Canadians' awareness to the risks associated with a contaminated water supply has been heightened in the aftermath of recent outbreaks of Escherichia coli O157:H7, Campylobacter, and Cryptosporidium. The main objectives of this research were to describe the incidence and distribution of select waterborne disease outbreaks in Canada in relation to preceding weather conditions and to test the association between high impact weather events and waterborne disease outbreaks.
Methods:
We examined extreme rainfall and spring snowmelt in association with 168 Canadian waterborne disease outbreaks between 1975 and 2001, categorized as possibly, probably or definitely waterborne, using case-crossover methodology. Explanatory variables including daily rainfall amount, air temperature, and peak stream flow were used to determine the relationship between high impact weather events and the occurrence of waterborne disease outbreaks.
Results:
For probable and definite waterborne disease outbreaks we found an association between total maximum degree-days above 0oC and maximum 5-day rolling cumulative average rainfall percentile with risk of outbreak. For each degree-day above 0oC the relative odds of an outbreak increased by a factor of 1.00672 (95% confidence interval [CI] = 1.00166- 1.01181). We dichotomized maximum rainfall percentile and found an increased risk at the 93rd percentile. For rainfall events greater than the 93rd percentile the relative odds of an outbreak increased by a factor of 2.28311 (95% [CI] = 1.21644-4.28512).
Conclusion:
These results suggest that weather is possibly a contributing factor to waterborne disease outbreaks in Canada. This could have implications for water management and public health initiatives.
2005-04-06 |
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