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Surveillance Systems for Waterborne Cryptosporidium: US EPA method 1523 and Beyond
Citation:
VILLEGAS, E. Surveillance Systems for Waterborne Cryptosporidium: US EPA method 1523 and Beyond. Presented at 2009 USDA-CSREES National Water Conference, St. Louis, MO, February 08 - 12, 2009.
Impact/Purpose:
The overall objective of this task is the development of improved occurrence detection methods for protozoan parasites and Microsporidia. Since this work is a primary focus of the Branch, this task supports several individual projects related to sample preparation and protozoan detection. Together these projects will lead to complete methods able to support the UCMR and the CCL2 and CCL3.
Description:
Waterborne cryptosporidiosis remains a significant public health concern in countries around the world. Many species and genotypes of Cryptosporidium contaminate drinking water sources, but C. parvum and C. hominis remain the two predominant species known to cause waterborne disease outbreaks in humans. To improve human health and reduce risks posed by these pathogens, the US EPA promulgated the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule). This rule requires drinking water utilities to monitor for Cryptosporidium oocysts in their source waters using US EPA Method 1622 or 1623. These methods are designed to enumerate oocysts by microscopy and although very useful in determining concentration levels of Cryptosporidium oocysts in various drinking water sources throughout US, the methods are time consuming, labor intensive and cannot distinguish animal from human specific species or determine if the oocysts are infectious to humans. Because many Cryptosporidium spp. oocysts are morphologically similar and can contaminate drinking water supplies, the development of more specific detection and typing approaches for this parasite are essential to better understand the impact of this protozoan in source waters. The data generated by these methods will provide additional information that will be useful for future source water management strategies and for human health risk assessments related to Cryptosporidium oocyst contamination. Current research activities focused on developing new and more rapid molecular-based approaches (e.g., quantitative real-time PCR, microarrays, etc.) that can detect and determine the infectious potential of oocysts will be described. Advantages and inherent limitations of these approaches and their potential application(s) as alternative methods to current Cryptosporidium surveillance systems will be discussed.