1993年3月和4月，美国最大的水传播疾病暴发发生在威斯康星州密尔沃基，导致40多万人患病。大多数病例的病原是隐孢子虫。密尔沃基有两家水处理厂，它们使用密歇根湖的原水。在疫情暴发之前，严重的春季风暴导致湖泊的浑浊度和细菌数量急剧上升。在疫情暴发期间，一家工厂产生的废水浊度接近2.5 ntu，这一高读数表明通过该工厂的颗粒物增加。颗粒物的增加可能也意味着隐孢子虫卵囊的传代增加。 本文讨论了美国环境保护署供水和水资源部（前饮用水研究部）对卵囊通过处理厂可能发生的情况进行的调查。包括5个参考文献、表格、图表。

In March and April 1993, the largest US waterborne disease outbreak occurred in Milwaukee, Wisconsin, causing illness in more than 400,000 people. The etiological agency responsible for most cases was Cryptosporidium. Milwaukee was served by two water treatment plants that used raw water from Lake Michigan. Before the outbreak, severe spring storms caused the lake's turbidity and bacterial counts to rise dramatically. During the outbreak, effluent produced by one plant had a turbidity approaching 2.5 ntu, a high reading that indicated an increase in particulates passing through the plant. This increase in particulates may have also meant an increase in passage of Cryptosporidium oocysts. This article discusses the investigation by the Water Supply and Water Resources Division (formerly the Drinking Water Research Division) of the US Environmental Protection Agency into what may have happened to allow the oocysts to pass through the treatment plant. Includes 5 references, table, figures.