Association between Extreme Precipitation, Drinking Water and Acute Gastro Intestinal Illness in the Fraser Health Authority, British Columbia, Canada, 2000-2012

Field: Health Professions (Health Sciences)

Association between Extreme Precipitation, Drinking Water and Acute Gastro Intestinal Illness in the Fraser Health Authority, British Columbia, Canada, 2000-2012Abstract Number:2212 Bimal Chhetri*, Eleni Galanis, Sunny Mak, Marc Zubel, Michael Otterstatter, Robert Balshaw, Jordan Brubacher, Manon Fleury, Marcus Lem, Sylvia Struck, Joanne Edwards, and Timothy Takaro Bimal Chhetri* British Columbia Centre for Disease Control, Canada, E-mail Address: [email protected] , Eleni Galanis British Columbia Centre for Disease Control, Canada , Sunny Mak British Columbia Centre for Disease Control, Canada , Marc Zubel Fraser Health Authority, Canada , Michael Otterstatter British Columbia Centre for Disease Control, Canada , Robert Balshaw British Columbia Centre for Disease Control, Canada , Jordan Brubacher Simon Fraser University, Canada , Manon Fleury Public Health Agency of Canada, Canada , Marcus Lem Fraser Health Authority, Canada , Sylvia Struck BC Centre for Disease Control, Canada , Joanne Edwards British Columbia Ministry of Health, Canada , and Timothy Takaro Simon Fraser University, Canada AbstractIntroduction The burden of waterborne acute gastrointestinal illness (AGI) could increase with the increased precipitation extremes expected due to climate change. Understanding the relationship between weather, drinking water systems (DWS) and AGI can help increase adaptive capacity to climate change. Here, we present findings of our study which investigates the relationship between two parasitic gastrointestinal illnesses, extreme precipitation and DWS.Methods We included weekly reported cases of cryptosporidiosis and giardiasis from 2000-2012 in the Fraser Health Authority (FHA), British Columbia. Each case's corresponding DWS was determined based on address of residence. The associations between weekly reported cases from each DWS and extreme precipitation (>90th percentile) were assessed using distributed lag non-linear Poisson regression models adjusted for seasonality, long term trend and mean temperature. We used 0-8 week lag periods to account for the expected time delay between precipitation and case reporting.Results Preliminary analyses comprising of 3483 cases indicate a significant association between extreme precipitation and weekly cases reported at 4 to 6 weeks lags (RR =1.17, 95% CI =1.09-1.26 for lag 5) in a large municipal surface DWS in 2000-2009. However, this association was not evident in the same DWS after 2009, when a partial filtration system became operational. Further, there was no statistical evidence of an association between extreme precipitation and weekly case counts from other DWS.Conclusions These exploratory results show a temporal relationship between initiation of a new filtration system and the effect of precipitation on the burden of cryptosporidiosis and giardiasis in populations using this large DWS. Further analyses will be conducted to confirm this association and considerations will be given to estimate the future burden of AGI using climate projection models.