Detection and Genotyping of Cryptosporidium Oocysts in Eastern Pennsylvania Water Supplies

Water samples were obtained from the Monocacy Creek Watershed and the Schuylkill River Watershed in eastern Pennsylvania in order to monitor for multiple species of Cryptosporidium oocysts. Filter samples were collected from the intake at the Philadelphia Water Department's Queen Lane Water Treatment Plant (WTP) in the Schuylkill River in Philadelphia, PA and from Monocacy Creek in Bethlehem, PA. Water filtration was followed by immunomagnetic separation to isolate oocysts and then the oocysts were processed by genotyping (i.e., DNA extraction, nested polymerase chain reaction, cloning and sequencing) to determine the individual species of Cryptosporidium to assess the potential threat to human health.;Out of 33 filter samples at the Queen Lane WTP over a period of nine months, six (18.2%) were positive for Cryptosporidium oocysts. The phylogenetic analysis of oocyst genotypes showed that five different genotypes were found. The detection of human infectious genotypes in the Schuylkill River Watershed confirmed a potential risk to human health associated with using the Schuylkill River as a drinking water source. Out of 14 filter samples at Monocacy Creek over a period of nine months, one (7.1%) was positive for Cryptosporidium.;In addition, a method for genotyping oocysts that have already been processed by fluorescent in situ hybridization (FISH) was developed. This method was effective in confirming the presence of human infectious genotypes of Cryptosporidium at the Queen Lane WTP intake and at two additional sites.