AWWA JAW41470

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.