Associations between Five Food and Waterborne Diseases and Ecosystem Classification, Aquifer Type and Agricultural Land in a Changing Climate

Abstract

Background: All organisms are distributed unevenly across Earth's surface. The extent to which spatial heterogeneity among food and waterborne pathogens can be attributed to specific environmental processes remains largely unknown, although evidence suggests that climate change will alter these processes. Methods: The rates of five acute gastrointestinal illnesses (AGIs) from 2000 to 2013 in British Columbia, Canada were calculated across three environmental variables: ecological zone, aquifer type and agricultural land. Annual climatic variables at the ecological zone scale were used to calculate relative disease risk per degree Celsius. Findings: Each of the bacterial AGIs was correlated with many annual temperature-related variables. Combined relative risk for the three bacterial AGIs was 1.11189 (p=0.006) for every degree Celsius of warming. In rural areas, bacteria and protozoa had significantly higher proportions associated with unconsolidated aquifers than with bedrock aquifers. Verotoxin-producing Escherichia coli rates were significantly higher in watersheds with higher proportions of agricultural land (of any kind) than in those with none, while rates of campylobacteriosis, salmonellosis and giardiasis were significantly lower in agricultural watersheds. Spatial distributions of all AGIs were projected to change with climate change. Interpretation: These findings suggest that risk of AGI can vary across land use, aquifer type and ecosystem and that warming temperatures can be associated with an increased risk of disease. This study may provide insight into some of the ecological processes impacting the distribution of these organisms. Funding Statement: Funding was provided by the Pacific Institute for Climate Solutions in the form of a graduate fellowship. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This study was reviewed by the Simon Fraser University Research Ethics Board and approved on 12 Jun 2014 (no. 2013s0706).