在代表暴发的条件下，模拟了100-L体积的处理水“斑点”样本中隐孢子虫卵囊的计数。这些数字与英国和美国疫情报告的数字非常吻合。100-L样本中有33%不含卵囊，而一小部分含有数百甚至数千个卵囊。隐孢子虫感染的风险与进入处理水中分配系统的卵囊总数直接相关，用算术平均卵囊密度表示。基于单点100-L体积样本的监测项目往往会错过“所有重要”的高计数样本，从而低估算术平均值和对公共健康的风险。因此，记录每100升0个卵囊的斑点样本提供的保证很少。检测以不频繁的高频形式出现的时间变化- 计数峰值，英国的隐孢子虫法规要求在处理水离开处理设施时对其进行持续监测。包括37个参考文献、表格、图表。

Counts of Cryptosporidium oocysts in 100-L volume "spot" samples of treatedwater have been simulated for conditions representative of an outbreak. The counts agree well with those reported in outbreaks in the United Kingdom and the United States. Whereas 33 percent of 100-L samples contained no oocysts, a small proportion contained hundreds and even thousands of oocysts. The risk of Cryptosporidium infection is directly related to the total number of oocysts entering the distribution system in the treated water as represented by the arithmetic mean oocysts density. Monitoring programs based on taking single spot 100-L volume samples will tend to miss the "all important" high-count samples and thus underestimate the arithmetic mean and the risk to public health. Spot samples recording 0 oocysts/100 L therefore provide very little reassurance. To detect temporal variation in the form of infrequent high-count spikes, the Cryptosporidium regulations in the United Kingdom require continuous monitoring of treated water as it leaves the treatment facility. Includes 37 references, tables, figures.