Inactivation of Cryptosporidium Parvum in Natural Waters Using Free Chlorine

Waterborne transmission of disease has been documented throughout history. One of the greatest contributions to 20% century society has been the advent and application of water treatment technologies. However, analysis of current World Health Organization (WHO) estimates of illness and mortality and epidemiological investigations in the United States still indicates that the threat to public health from waterborne disease still exists There are a plethora of contaminants (both chemical and microbiological) that impose a direct risk to public health in the United States. The United States Environmental Protection Agency (EPA) reviews these contaminants and focuses its efforts upon the chemicals and microorganisms that are entered on the Contaminant Candidate List (CCL). Although it has never appeared on the CCL, a large amount of research during the 1990s was focused upon Cryptosporidium parvum, a pathogenic waterborne parasite, to fmd methods and techniques to measure, remove, and inactivate it in drinking water supplies. C. parvum gained national public attention in 1993 when cryptosporidiosis in Milwaukee, Wisconsin infected an estimated 403,000 people and killed an estimated 65 to 100 people (MacKenzie, et al., 1994).