AWWA WQTC62400

The objective of this study was to determine the distribution of Cryptosporidium parvum, Cryptosporidium hominis and Giardia lamblia in the Township of Langley, an urban-rural community in the Lower Mainland of BC and to characterize the isolates using molecular methods. Water sources in Langley range from public and private systems extracting water from both surface and groundwater, with public surface water and groundwater systems being treated by chlorination in the absence of filtration. This study site is currently the site of a three-year research project investigating the environmental contributants to waterborne illness. Water samples were collected from two surface water sources (Salmon River and its tributary, Coghlan Creek) one groundwater source (Arcadia Well, a municipal well that supplies a portion of Langley Township treated water) routinely over an eleven month period and were processed by filtration and immunomagnetic separation. The samples were tested using an immunofluorescence assay(IFA) for enumeration of Cryptosporidium oocysts and Giardia cysts. To confirm the results of the IFA and characterize the isolates, nested PCR and sequencing was used on select samples. The Arcadia Municipal Well was negative for both parasites for the entire study period with the exception of one sampling date when a low concentration of Cryptosporidium oocysts was detected (1.6 oocysts/100L). In the surface water samples, Giardia was detected more frequently (77%) than Cryptosporidium (53%) and at much higher concentrations. Fifteen samples were selected for molecular analysis. Nested PCR targeting the 18s rRNA gene of Cryptosporidium sp. successfully amplified five out of ten samples positive for Cryptosporidium by IFA. Seven out of fifteen samples positive for Giardia by IFA were positive by PCR targeting the ß-giardin gene. Sequencing of the PCR-positive samples revealed that the Cryptosporidium isolates identified in this study had high sequence identity to environmental Cryptosporidium species and to C. parvumstrains. Sequencing of the Giardia isolates revealed that all samples belonged to Assemblage B. Langley's multiple water systems and its mixture of urban and ruralsetting is representative of many systems in North America and allows for transferability of results. Includes 20 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

15

File Size:

1 file , 1.1 MB