Citation:

Simmons, O. D., D. S. Francy, E. J. Granger, M W. Ware, M. D. Sobsey, AND F W. Schaefer III. EVALUATION OF SPIKING PROCEDURES FOR RECOVERY OF CRYPTOSPORIDIUM IN STREAM WATERS USING USEPA METHOD 1623. Presented at 104th General Meeting of the American Society for Microbiology, New Orleans, LA, May 23-27, 2004.

Impact/Purpose:

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.

Description:

U.S. Environmental Protection Agency Method 1623 is widely used to monitor source waters and drinking water supplies for Cryptosporidium oocysts. Analyzing matrix spikes is an important component of Method 1623. Matrix spikes are used to determine the effect of the environmental matrix on the method's recovery efficiency for the target organism and require the collection and analysis of two environmental samples. Using a new product, ColorSeed, spiked organisms can be differentiated from unmodified organisms and thus recovery efficiencies can be determined by analyzing only one environmental sample. Twenty-nine stream-water samples and one effluent sample were collected to compare ColorSeed to traditional spiking procedures. Adjusted recoveries of oocysts ranged from 2.8 to 49 percent for viable oocysts (traditional spiking procedure) and 3.1 to 59 percent for ColorSeed. The recoveries between the two spiking procedures were highly correlated (r = 0.802) and were not found to be significantly different. Recoveries using ColorSeed, therefore, were comparable to recoveries using traditional spiking procedures. Collecting and processing these samples afforded the opportunity to address other issues regarding the use of Method 1623 for monitoring environmental waters. In examining the effects of water-qualiy variables on method recovery efficiency of oocysts, significant negative correlations were found between average oocyst recovery and turbidity or suspended sediment; this was especially apparent in samples with turbidities greater than 100 NTU and suspended-sediment concentrations greater than 100 mg/L. Because oocysts were found in a small percentage of samples (16.7 percent), the presence of Cryptosporidium was qualitatively compared to concentrations of microbiological indicators and to concentrations of chemical constituents known to be associated with fecal contamination. Concentrations of E. coli, F-specific coliphage, and total phosphorus were above the median non-detection concentrations in all samples with detections of Cryptosporidium, but were not above the median for Cl. perfringens, somatic coliphage, chloride, and nitrate.

Record Details: