Development and application of a quantitative, specific assay for Cryptosporidium parvum oocyst detection in high-turbidity environmental water samples

Chlorine-resistant Cryptosporidium parvum oocysts in drinking water play an important role in the epidemiology of cryptosporidiosis. Current methods o f detecting these organisms in water are insensitive, labor-intensive, high ly subjective, and severely limited by sample turbidity. We describe here a n alternative technique utilizing electrochemiluminescence (ECL) technology for detecting C. parvum oocysts in environmental water samples. This metho d is quantitative, reproducible, and requires only minimal sample processin g. Currently, the ECL assay can detect as few as one oocyst in one millilit er of concentrated test sample with sample turbidity of up to 10,000 nephel ometric turbidity units. Water and sewer samples collected during a cryptos poridiosis outbreak were tested by ECL assay. Cryptosporidium parvum oocyst s were found in the source water at the time of outbreak, and a sharply dec reasing level of oocysts in sewer samples was observed over a three-month p eriod following the outbreak.