Using rapid indicators for Enterococcus to assess the risk of illness after exposure to urban runoff contaminated marine water
Traditional fecal indicator bacteria (FIB) measurement is too slow (>18 h) for timely swimmer warnings. Assess relationship of rapid indicator methods (qPCR) to illness at a marine beach impacted by urban runoff. We measured baseline and two-week health in 9525 individuals visiting Doheny Beach 2...
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Published in | Water research (Oxford) Vol. 46; no. 7; pp. 2176 - 2186 |
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Main Authors | , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier Ltd
01.05.2012
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Traditional fecal indicator bacteria (FIB) measurement is too slow (>18 h) for timely swimmer warnings.
Assess relationship of rapid indicator methods (qPCR) to illness at a marine beach impacted by urban runoff.
We measured baseline and two-week health in 9525 individuals visiting Doheny Beach 2007–08. Illness rates were compared (swimmers vs. non-swimmers). FIB measured by traditional (Enterococcus spp. by EPA Method 1600 or Enterolert™, fecal coliforms, total coliforms) and three rapid qPCR assays for Enterococcus spp. (Taqman, Scorpion-1, Scorpion-2) were compared to health. Primary bacterial source was a creek flowing untreated into ocean; the creek did not reach the ocean when a sand berm formed. This provided a natural experiment for examining FIB-health relationships under varying conditions.
We observed significant increases in diarrhea (OR 1.90, 95% CI 1.29–2.80 for swallowing water) and other outcomes in swimmers compared to non-swimmers. Exposure (body immersion, head immersion, swallowed water) was associated with increasing risk of gastrointestinal illness (GI). Daily GI incidence patterns were different: swimmers (2-day peak) and non-swimmers (no peak). With berm-open, we observed associations between GI and traditional and rapid methods for Enterococcus; fewer associations occurred when berm status was not considered.
We found increased risk of GI at this urban runoff beach. When FIB source flowed freely (berm-open), several traditional and rapid indicators were related to illness. When FIB source was weak (berm-closed) fewer illness associations were seen. These different relationships under different conditions at a single beach demonstrate the difficulties using these indicators to predict health risk.
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► Cohort design evaluated swimmer health-fecal indicator bacteria (FIB) relationships. ► Rapid (qPCR) and traditional (culture-based) methods used to enumerate FIB. ► Swimming, and increased water exposure, associated with negative health outcomes. ► Health-FIB relationship depended on beach conditions and swimmer’s water exposure. ► Demonstrated difficulties using FIB to predict health outcomes at marine beach. |
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Bibliography: | http://dx.doi.org/10.1016/j.watres.2012.01.033 Prestent Affiliation: Kaiser Permanente Division of Research, 2000 Broadway Oakland, CA 94612, USA |
ISSN: | 0043-1354 1879-2448 |
DOI: | 10.1016/j.watres.2012.01.033 |