在加拿大和其他工业化国家，指导方针、法规和 良好的管理实践有助于确保降低感染传染病的风险 从饮用水中提取的水分非常低。尽管如此，水性肠胃炎的暴发 即使在没有细菌学指标的情况下也会发生。定量微生物 适用于饮用水的风险评估（QMRA）工具提供了一种基于风险的方法来评估 了解饮用水处理障碍以及它们之间的相互作用如何 影响来自病原体的人类健康风险。 加拿大卫生部和DecisionAnalysis Risk Consultants Inc.开发了一种概率分析方法 评估接触指数病原体对人类健康风险水平的模型 在经过处理的饮用水中。该模型探讨了水处理对环境的影响 与饮用水中发现的病原体相关的疾病负担，即 微小隐孢子虫、蓝氏贾第虫、轮状病毒和致病性大肠杆菌。 该模型产生的主要估计包括:病原体水平的降低 由于治疗障碍；预计每年从 经处理饮用水中的参考病原体；此外，疾病负担可归因于 经过处理的饮用水。为了说明该工具的使用，来自渥太华市的数据 用于估计许多当前和未来治疗方案对患者的影响 水传播疾病的风险。结果用于比较数据的相对重要性 最佳和非最佳操作条件下的多重处理屏障。后果 也用于确定初级消毒的最佳处理目标。这个 QMRA模型提供了一个框架，用于理解环境中微生物风险的性质 饮用水供应系统，并可用于评估水质变化的影响 对人群健康风险的治疗。包括29个参考文献、表格和图表。

In Canada and other industrialized nations, a combination of guidelines, regulations and good management practices help ensure that the risk of contracting infectious disease from drinking water is very low. Despite this, outbreaks of waterborne gastroenteritis have occurred, even in the absence of bacteriological indicators. Quantitative microbial risk assessment (QMRA) tools applied to drinking water offer a risk-based approach to understanding how drinking water treatment barriers, and interactions between them, may impact human health risk from pathogens. Health Canada and Decisionalysis Risk Consultants Inc. have developed a probabilistic model that estimates the level of risk to human health from exposure to index pathogens in treated drinking water. The model explores the impact of water treatment upon the burden of disease associated with pathogens found in drinking water, namely Cryptosporidium parvum, Giardia lamblia, Rotavirus, and pathogenic Escherichia coli. The primary estimates produced by the model include: the reduction in pathogen levels as a result of treatment barriers; the expected number of illnesses per year from the reference pathogens in treated drinking water; and, the disease burden attributable to the treated drinking water. To illustrate the use of the tool, data from the City of Ottawa is used to estimate the impact of a number of current and future treatment scenarios on the risk of waterborne disease. Results are used to compare the relative importance of multiple treatment barriers during optimal and non-optimal operating conditions. Results are also used to determine optimum treatment targets for primary disinfection. The QMRA model provides a framework for understanding the nature of microbial risk in a drinking water supply system, and can be used to evaluate the impact of changes in water treatment on population health risk. Includes 29 references, tables, figures.