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LOW PRESSURE ULTRAVEIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS
Hayes, S L., E W. Rice, M W. Ware, AND F W. Schaefer III. LOW PRESSURE ULTRAVEIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS. JOURNAL OF APPLIED MICROBIOLOGY 94(1):54-59, (2003).
1) Refine new, practical methods for the detection of CCL-related and emerging waterborne human protozoa.
2) Perform field tests of devices or methods that have been developed under this task.
3) Evaluate these methods or devices in a variety of water matrices and parasite concentrations.
This work in this task supports CCL2 and 3 and is expected to be completed by 9/07.
Cysts of Giardia muris were inactivated using a low pressure ultravolet (UV) light source. Cyst viability was detemined by both in vitro excystation and animal infectivity. Cyst doeses were counted using a flow cytometer for the animal infectivity experiments. Using in vitro excystation as the viability indicator, fluences as high as approximately 200 mJ/cm(2) did not prevent some cysts from excysting, thus verifying earlier work. Using animal infectivity, UV fluences of 1.4, 1.9 and 2.3 mJ/cm(2) yielded log(10) reductions ranging from 0.3 to greater than or equal to 4.4. Results indicate in vitro excystation is not a reliable indicator of G. muris cyst viability after UV disinfection.