Grantee Research Project Results
Final Report: Rapidly Measured Indicators of Waterborne Pathogens
EPA Grant Number: R834789Title: Rapidly Measured Indicators of Waterborne Pathogens
Investigators: Dorevitch, Samuel , Bushon, Rebecca N , Lin, King-Teh , Liu, Li , Scheff, Peter , Cali, Salvatore
Institution: University of Illinois at Chicago , MycoMetrics , USGS Biological Resources Division
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 2011 through January 31, 2014 (Extended to January 31, 2015)
Project Amount: $499,831
RFA: Exploring Linkages Between Health Outcomes and Environmental Hazards, Exposures, and Interventions for Public Health Tracking and Risk Management (2009) RFA Text | Recipients Lists
Research Category: Human Health
Objective:
The overarching objective of this work was to identify microbial measures of water quality that could be used in beach monitoring that would improve public health protection. The objectives of this research as originally proposed were: 1) to analyze archived water samples from a large prospective cohort study of water recreation, by qPCR, 2) to compare four rapidly measured indicators as predictors of pathogen presence, 3) to identify thresholds for the rapid indicators that maximize the accurate prediction of pathogen presence, and 4) to field -test two methods for rapidly measuring indicators at a busy swimming beach, and to evaluate beach management decisions that result for the use conventional and the rapidly measured pathogen indicators. Additionally, in 2014 we added the goal of analyzing water quality indicators as predictors of illness occurrence and illness severity among water recreators.
Summary/Accomplishments (Outputs/Outcomes):
A goal of the Clean Water Act is to ensure that surface waters of the United States support recreation in and on the water. In late 2012 EPA issued new Recreational Water Quality Criteria (RWQC) to promote effective monitoring of recreational waters. The new criteria included for the first time the option of monitoring water quality using the qPCR method. The new RWQC also created a pathway for States to establish site-specific criteria that would utilize newer methods of measuring water quality. An aim of this research has been to evaluate the performance characteristics of several new methods of measuring water quality. The methods evaluated were (IMS/ATP for E. coli, IMS/ATP for enterococci, culture for E. coli, culture for enterococci, qPCR for enterococci, and EasyPhage). Enterococci measured by qPCR had substantially better precision for measuring microbes in beach water samples than did the other methods. All methods other than IMS/ATP (with the testing protocol and reagents used in our setting) had acceptable accuracy.
Another aim of this project has been to compare indicators microbes as predictors of pathogen presence. Receiver operating characteristics (ROC) methods were used for that analysis. In general, the indicators were better predictors of Giardia spp. presence than of Cryptosporidium spp. presence. Additionally, differences were identified among indicators in their ability to correctly differentiate pathogen presence from pathogen absence in recreational waters. The qPCR method and the rapid coliphage method performed significantly better than the other methods. The ROC approach was used to optimize indicator concentrations so that sensitivity and specificity are simultaneously maximized. The results suggests that for the Chicago area waters studied, the ROC-optimized indicator values for predicting Giardia presence are within approximately 50% of the “Beach Action Values” (BAV) proposed in the 2012 RWQC for an estimated illness rate of 32 cases/ 1,000 primary contact recreators. All optimized indicator values result in good positive predictive value, but poor negative predictive value. From the standpoint of public health, this is problematic. In other words, use of a notification system based on the optimized values would be wrong about half the time when Giardia absence is suggested by indicator tests (negative predictive values of about 50%). The fact that the qPCR BAV is less than the ROC -optimized threshold means that the negative predictive value at the BAV would be better than the optimized value (at the expense of lowering the positive predictive value).
The analysis of data from the CHEERS study of limited contact water recreation suggests that water quality metrics do not predict the occurrence of illness; other factors, such as the presence of a chronic gastrointestinal illness, fishing (as opposed to other limited contact activities), and exposure of the face to water increase the likelihood of illness.
Prior epidemiologic studies of water quality indicators and health have focus on whether the indictors predict illness occurrence, without taking into account illness severity. We analyzed data to assess environmental public health indicators as predictors of gastrointestinal illness severity among swimmers in a previously conduct cohort study. We found that a method developed by EPA for rapidly indicating water quality (enterococci DNA measured by quantitative polymerase chain reaction) is a better predictor of GI illness severity than conventional methods. This suggests that the method has added value as an environmental public health indicator to beach manager. By contrast, in analysis of our data of limited contact water recreation (such as fishing, canoeing, kayaking and boating) in Chicago (CHEERS study), measures of water quality did not predict the severity of illness.
Conclusions:
A variety of environmental public health indicators are available for assessing the acute health hazards posed by microbes in surface waters. Several of those indicators were evaluated in this research. Findings suggest that qPCR measures of enterococci are relatively accurate relative to other methods evaluated. Based on analyses of water samples from Chicago area surface waters, the indicators are better predictors of Giardia presence than they are predictors of Cryptosporidium presence. The indicators are reasonable predictors of pathogen presence, but perform less well as predictors of pathogen absence. qPCR measures of enterococci are useful as predictors of the severity of gastrointestinal illness among swimmers at several marine and Great Lakes beaches.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
Other project views: | All 11 publications | 4 publications in selected types | All 4 journal articles |
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DeFlorio-Barker S, Wade TJ, Turyk M, Dorevitch S. Water recreation and illness severity. Journal of Water and Health 2016;14(5):713-726. |
R834789 (Final) |
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DeFlorio-Barker S, Wade TJ, Jones RM, Friedman LS, Wing C, Dorevitch S. Estimated costs of sporadic gastrointestinal illness associated with surface water recreation:a combined analysis of data from NEEAR and CHEERS studies. Environmental Health Perspectives 2017;125(2):215-222. |
R834789 (Final) |
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Dorevitch S, DeFlorio-Barker S, Jones RM, Liu L. Water quality as a predictor of gastrointestinal illness following incidental contact water recreation. Water Research 2015;83:94-103. |
R834789 (Final) |
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Yavuz BM, Jones RM, DeFlorio-Barker S, Vannoy E, Dorevitch S. Receiver-operating characteristics analysis: a new approach to predicting the presence of pathogens in surface waters. Environmental Science & Technology 2014;48(10):5628-5635. |
R834789 (2013) R834789 (Final) |
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Supplemental Keywords:
Beaches, biology, coliphage, environmental public health indicators, environmental microbiology, gastrointestinal illness, Great Lakes, IL, indicator bacteria, microbiology, PCR, polymerase chain reaction, qPCR, Region V, water pollution, water quality, waterborne disease, beach water quality;Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.