title: Estimating the burden of acute gastrointestinal illness due to Giardia, Cryptosporidium, Campylobacter, E. coli O157 and norovirus associated with private wells and small water systems in Canada.
abstract: Waterborne illness related to the consumption of contaminated or inadequately treated water is a global public health concern. Although the magnitude of drinking water-related illnesses in developed countries is lower than that observed in developing regions of the world, drinking water is still responsible for a proportion of all cases of acute gastrointestinal illness (AGI) in Canada. The estimated burden of endemic AGI in Canada is 20·5 million cases annually - this estimate accounts for under-reporting and under-diagnosis. About 4 million of these cases are domestically acquired and foodborne, yet the proportion of waterborne cases is unknown. There is evidence that individuals served by private systems and small community systems may be more at risk of waterborne illness than those served by municipal drinking water systems in Canada. However, little is known regarding the contribution of these systems to the overall drinking water-related AGI burden in Canada. Private water supplies serve an estimated 12% of the Canadian population, or ~4·1 million people. An estimated 1·4 million (4·1%) people in Canada are served by small groundwater (2·6%) and surface water (1·5%) supplies. The objective of this research is to estimate the number of AGI cases attributable to water consumption from these supplies in Canada using a quantitative microbial risk assessment (QMRA) approach. This provides a framework for others to develop burden of waterborne illness estimates for small water supplies. A multi-pathogen QMRA of Giardia, Cryptosporidium, Campylobacter, E. coli O157 and norovirus, chosen as index waterborne pathogens, for various source water and treatment combinations was performed. It is estimated that 103 230 AGI cases per year are due to the presence of these five pathogens in drinking water from private and small community water systems in Canada. In addition to providing a mechanism to assess the potential burden of AGI attributed to small systems and private well water in Canada, this research supports the use of QMRA as an effective source attribution tool when there is a lack of randomized controlled trial data to evaluate the public health risk of an exposure source. QMRA is also a powerful tool for identifying existing knowledge gaps on the national scale to inform future surveillance and research efforts.
authors.affiliation: Centre for Food-borne,Environmental and Zoonotic Infectious Diseases,Public Health Agency of Canada,Guelph,ON,Canada.
authors.forename: H M
authors.initials: HM
authors.lastname: Murphy
authors.affiliation: Centre for Food-borne,Environmental and Zoonotic Infectious Diseases,Public Health Agency of Canada,Guelph,ON,Canada.
authors.forename: M K
authors.initials: MK
authors.lastname: Thomas
authors.affiliation: Department of Civil and Environmental Engineering,University of Waterloo,Waterloo,ON,Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Schmidt
authors.affiliation: Water and Air Quality Bureau,Healthy Environments and Consumer Safety Branch,Health Canada,Ottawa,ON,Canada.
authors.forename: D T
authors.initials: DT
authors.lastname: Medeiros
authors.affiliation: Water and Air Quality Bureau,Healthy Environments and Consumer Safety Branch,Health Canada,Ottawa,ON,Canada.
authors.forename: S
authors.initials: S
authors.lastname: McFADYEN
authors.affiliation: Centre for Food-borne,Environmental and Zoonotic Infectious Diseases,Public Health Agency of Canada,Guelph,ON,Canada.
authors.forename: K D M
authors.initials: KD
authors.lastname: Pintar
mesh_terms: D000208:Acute Disease; D002170:Canada / Q000453:epidemiology; D060766:Drinking Water / Q000382:microbiology* / Q000469:parasitology* / Q000821:virology; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000469:parasitology; D060587:Groundwater / Q000382:microbiology* / Q000469:parasitology* / Q000821:virology; D006801:Humans; D011159:Population Surveillance / Q000379:methods*; D018570:Risk Assessment; D014881:Water Supply / Q000592:standards
chemical_list: D060766:Drinking Water
keywords: Water (quality); burden; private wells; small drinking water systems; waterborne illness