1994年初，内华达州拉斯维加斯的艾滋病人群爆发隐孢子虫病时，克拉克县卫生区要求疾病控制和预防中心（CDC）协助确定爆发原因。CDC的流行病学研究结果表明，与饮用瓶装水或过滤水相比，在拉斯维加斯饮用自来水的艾滋病患者感染隐孢子虫病的风险更大。AWWA研究基金会同行评审小组同意CDC，流行病学证据指出自来水是疫情爆发的唯一危险因素。这次疫情的矛盾之处在于，处理厂的进水水质没有变化，没有发现任何处理故障或缺陷，疫情的结束和开始一样突然，水处理没有变化。包括9个参考文献、表格、图表。

When Las Vegas, Nevada, experienced an outbreak of cryptosporidiosis in the AIDS population early in 1994, the Clark County Health District requested that the Centers for Disease Control and Prevention (CDC) assist in determining the cause of the outbreak. Results of CDC's epidemiological study indicated that AIDS patients drinking tap water in Las Vegas are at greater risk of contracting cryptosporidiosis than if they consume bottled or filtered water. An AWWA Research Foundation peer review panel concurred with the CDC that the epidemiological evidence pointed to tap water as the only risk factor in the outbreak. The paradox of this outbreak is that the influent water quality at the treatment plant did not change, no treatment breakdowns or deficiencies were identified, and the outbreak ended as suddenly as it began, with no changes in water treatment. Includes 9 references, tables, figures.