Associations between biogeoclimatic zones, aquifer type, agricultural land and five gastrointestinal illnesses in British Columbia from 2000-2013 and potential implications under projected climate change

Rates of five acute gastrointestinal illnesses (AGIs) were calculated across three environmental variables in British Columbia: biogeoclimatic zone, aquifer type and agricultural land. The three bacterial pathogens (campylobacteriosis, Verotoxin-producing Escherichia coli and salmonellosis) were strongly correlated with many temperature-related variables calculated at the biogeoclimatic zone level. Combined relative risk for the three bacterial AGIs was 1.11189 (p=0.006) for every degree Celsius increase in mean annual temperature. When amalgamated into two groups (bacteria and parasites) both groups had significantly higher proportions associated with unconsolidated aquifers than with bedrock aquifers. Verotoxin-producing Escherichia coli rates were significantly higher in watersheds with agricultural land than those with none. Conversely, rates of campylobacteriosis, salmonellosis and giardiasis were significantly lower in agricultural watersheds.