Climate change is already impacting the North American Great Lakes ecosystem and understanding the relationship between climate events and public health, such as waterborne acute gastrointestinal illnesses (AGIs), can help inform needed adaptive capacity for drinking water systems (DWSs). In this study, we assessed a harmonized binational dataset for the effects of extreme precipitation events (≥90th percentile) and preceding dry periods, source water turbidity, total coliforms, and protozoan AGIs – cryptosporidiosis and giardiasis – in the populations served by four DWSs that source surface water from Lake Ontario (Hamilton and Toronto, Ontario, Canada) and Lake Michigan (Green Bay and Milwaukee, Wisconsin, USA) from January 2009 through August 2014. We used distributed lag non-linear Poisson regression models adjusted for seasonality and found extreme precipitation weeks preceded by dry periods increased the relative risk of protozoan AGI after 1 and 3–5 weeks in three of the four cities, although only statistically significant in two. Our results suggest that the risk of protozoan AGI increases with extreme precipitation preceded by a dry period. As extreme precipitation patterns become more frequent with climate change, the ability to detect changes in water quality and effectively treat source water of varying quality is increasingly important for adaptive capacity and protection of public health.

气候变化已经在影响北美五大湖生态系统，了解气候事件与公共卫生之间的关系，例如水传播的急性胃肠道疾病 (AGI)，有助于了解饮用水系统 (DWS) 所需的适应能力。在这项研究中，我们评估了一个统一的两国数据集，以了解极端降水事件（≥90%）和之前的干旱期、水源浑浊度、总大肠菌群和原生动物 AGI（隐孢子虫病和贾第虫病）在四个 DWS 服务的人群中的影响2009 年 1 月至 2014 年 8 月从安大略湖（加拿大安大略省汉密尔顿和多伦多）和密歇根湖（美国威斯康星州绿湾和密尔沃基）获取地表水。我们使用了针对季节性调整的分布式滞后非线性泊松回归模型，发现干旱期之前的极端降水周增加了四个城市中三个城市在 1 周和 3-5 周后原生动物 AGI 的相对风险，尽管只有两个城市具有统计学意义。我们的研究结果表明，原生动物 AGI 的风险随着干旱期之前的极端降水而增加。随着气候变化导致极端降水模式变得更加频繁，检测水质变化和有效处理不同质量源水的能力对于适应能力和保护公众健康越来越重要。我们的研究结果表明，原生动物 AGI 的风险随着干旱期之前的极端降水而增加。随着气候变化导致极端降水模式变得更加频繁，检测水质变化和有效处理不同质量源水的能力对于适应能力和保护公众健康越来越重要。我们的研究结果表明，原生动物 AGI 的风险随着干旱期之前的极端降水而增加。随着气候变化导致极端降水模式变得更加频繁，检测水质变化和有效处理不同质量源水的能力对于适应能力和保护公众健康越来越重要。