Examining the Relationship Between Community Health Data and Pathogen Occurrence in Two Geographically Distinct Watersheds

Principal Investigator - Peter Huck, Professor, University of Waterloo (2005-2007)

Challenge

Although modern treatment strategies have greatly reduced the risk of disease from drinking water, pathogens (viruses, bacteria, and protozoa) in Canadian food and water continue to cause gastrointestinal, or enteric, disease. These cases are typically due to contamination by human or animal waste combined with a lack of or failure in water treatment, distribution and disinfection. While health surveillance can help to manage and control enteric disease, in the majority of cases the causal agent is unknown or the source cannot be determined. This is partly due to a lack of standardization in testing methods and outbreak investigations by public health authorities. There is also little information available on the exposure of humans to enteric pathogens through the various routes of transmission, including water, food, and contact with infected animals and humans. There is an important need for enhanced and integrated surveillance between pathogen exposure and enteric disease.

This project aimed to provide a collaborative environment for investigators and partners to advance research on the risk of waterborne enteric disease. The key users of the research outcomes are project partners, including regional water services, conservation authorities, and provincial and federal agencies.

Project

This project examined pathogen occurrence in two different watersheds used as drinking water sources, the Grand River in Ontario and the Lower Fraser Valley in British Columbia. Researchers developed and helped to standardize new detection and genotyping methods for waterborne pathogens. Initial studies used published and standard methods for culture-based isolation of bacterial pathogens and also quantitative PCR (qPCR) analysis. Overall studies looked at Cryptosporidium, Giardia, Campylobacter, Salmonella and verotoxigenic E. coli (E. coli O157:H7) using molecular biological methods, including quantitative PCR and microarray analysis.

The project team compared pathogen occurrence in water with human gastrointestinal disease through epidemiological studies using public health data. The team drew from projects at the Public Health Agency of Canada (C-EnterNet) and the BC Ministry of Health for the provision of human health data (enteric illness rates) to connect pathogen occurrence and human disease with human illness due pathogen exposure from water. The team also developed two assays using the electronic DNA microarray technology to specifically detect viable pathogens, including a Campylobacter electronic DNA microarray technique. This technique successfully identified Campylobacter in nineteen unknown culture samples and six chicken rinse samples.

In partnership with the C-EnterNet project, a surface water sampling program was implemented to isolate and identify pathogens from water used as a source of drinking water. Researchers then compared the levels and subtypes of isolated organisms with those from other sources, including data from C-EnterNet on pathogen occurrence in food, agricultural (on-farm) and human samples from the Region of Waterloo.

Outputs

• Standardization and validation of environmental microbiology methods, including pathogen detection and subtyping. The project provided an assessment of the presence and distribution of pathogens in drinking water sources
• Development of novel approaches to link water quality and human health data through attribution epidemiological investigations.
• Presentations made at regional, national and international conferences and workshops, attended by key stakeholders including water utilities, public health agencies, environment ministries and conservation groups (at local, provincial and national levels).
• Project research was made available in refereed journal publications. Project data and outcomes also published in C-EnterNet annual reports and newsletters available on the Public Health Agency of Canada website.
• Formation of a waterborne pathogen surveillance research network.
• Contribution to information and training for public health officials on optimized procedures and epidemiological investigations to more accurately predict pathogen sources during disease occurrence and outbreaks.

Outcomes

• Provided critical source water quality information for surveillance and assessment of treatment strategies by Canadian water utilities.
• Participation and communication with regional, provincial and federal regulatory agencies to allow the direct transfer of project results.
• Increased understanding of source water quality for groups studying watershed modeling, contamination impacts, and source water protection, based on assessments from this project.