Walkerton: Lessons learned in comparison with waterborne outbreaks in the developed world

Abstract

An estimated 2300 people became seriously ill and 7 died from exposure to microbially contaminated drinking water in the town of Walkerton, Ontario, in May of 2000. The severity of this drinking water disaster resulted in the Government of Ontario calling a public inquiry by Mr. Justice Dennis O'Connor to address the cause of the outbreak, the role, if any, of government policies in contributing to this outbreak, and ultimately, the implications of this experience on the safety of drinking water across the province of Ontario. This paper summarizes relevant evidence presented at the inquiry by the expert panel together with Justice O'Connor's findings addressing the circumstances of the outbreak. These findings are reviewed in relation to the published causes of previous waterborne disease outbreaks that have been reported elsewhere in developed countries. The circumstances surrounding the Walkerton tragedy are an important source of knowledge for those concerned with providing safe drinking water to the public. Although some circumstances are obviously specific to this epidemic, others echo common themes in waterborne outbreaks that have occurred before. These common themes suggest the need for attention to broad issues of drinking water safety in addition to the individual specific details that often command attention. Key words: waterborne disease, Escherichia coli O157:H7, Campylobacter jejuni, Cryptosporidium, Giardia, multiple barriers, health risk.

The occurrence and sources of Campylobacter spp., Salmonellaenterica and Escherichia coli O157:H7 in the Salmon River, British Columbia, Canada

“…Negative correlations were observed between Campylobacter isolations and faecal coliform rain (Hrudey et al 2002), the risk of waterborne disease in populations that drink untreated well water is also very high (Yoder et al 2008b). In Langley, more than 25% of the residents drink untreated well water, and previous research attributed elevated nitrate levels in both groundwater and surface water in this watershed to a high density of animal production units and septic systems (Wernick et al 1998).…”

“…Water contaminated with animal wastes has been linked to outbreaks of waterborne disease around the world (Hrudey et al 2002). Well-water sources under the influence of contaminated surface water are responsible for a disproportionate number of cases of waterborne disease outbreaks (Blackburn et al 2004;Smith et al 2006).…”

“…Well-water sources under the influence of contaminated surface water are responsible for a disproportionate number of cases of waterborne disease outbreaks (Blackburn et al 2004;Smith et al 2006). For example, in Walkerton Ontario, failure to adequately treat drinking water, intense rains, and surface water contaminated with cattle manure were responsible for a community outbreak of E. coli O157:H7 and Campylobacter infections which resulted in an estimated 2300 cases of gastrointestinal illness and seven deaths (Hrudey et al 2002;Auld et al 2004). In addition, the number of waterborne disease outbreaks associated with contaminated surface water used for recreational activities and irrigation of vegetable crops has been on the rise (Yoder et al 2008a).…”

Reduction of Escherichia coli, Salmonella Enteritidis and Campylobacter jejuni in poultry manure by rearing of Musca domestica fly larvae

“…Livestock production generates large amounts of manure, which can be used as fertiliser in agri-and horticulture. However, intensive livestock production is frequently located on farms which do not have enough land for proper utilisation of the manure, and this practice may lead to pollution of land, crops, water, and streams with phosphorous and nitrogen (Westerman and Bicudo, 2005) and/or zoonotic bacteria (Hrudey et al, 2002). Composting is one way to convert manure into a product which is easier to handle, but the process is time consuming (Westerman and Bicudo, 2005); hence, methods alternative to composting are needed.…”

Multi-Barrier Protection of Drinking Water Systems in Ontario: A Comparison of First Nation and Non-First Nation Communities

“…The Ontario Water Resources Act (1990), Environmental Protection Act (1990, and Environmental Bill of Rights (1993) are also important pieces of legislation. The multi-barrier approach includes the development of source water protection plans, creation of design standards for treatment technology, distribution systems, water quality monitoring, and emergency response preparedness (Hrudey, Hrudey, Huck, Payment, & Gillham, 2002). In Ontario, municipalities or townships are responsible for ensuring they meet the regulatory standards established by the province.…”