Using rapid indicators for Enterococcus to assess the risk of聽illness after exposure to urban runoff contaminated marine water

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• 作者：John M. Colford Jr.^a ; ^{jcolford@berkeley.edu} ; Kenneth C. Schiff^b ; John F. Griffith^b ; Vince Yau^a ; ¹ ; Benjamin F. Arnold^a ; Catherine C. Wright^a ; Joshua S. Gruber^a ; Timothy J. Wade^c ; Susan Burns^d ; Jacqueline Hayes^d ; Charles McGee^e ; Mark Gold^f ; Yiping Cao^b ; Rachel T. Noble^g ; Richard Haugland^h ; Stephen B. Weisberg^b
• 关键词：Gastrointestinal illness ; Recreational water quality ; Diarrhea ; Indicator organisms ; qPCR
• 刊名：Water Research
• 出版年：2012
• 期刊代码：57_00431354
• 类别：civ
• 出版时间：1 May, 2012
• 卷：46
• 期：7
• 页码：2176-2186
• 文件大小：265 K

摘要

Background

Traditional fecal indicator bacteria (FIB) measurement is too slow (>18聽h) for timely swimmer warnings.

Objectives

Assess relationship of rapid indicator methods (qPCR) to illness at a marine聽beach impacted by urban聽runoff.

Methods

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鈩? 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.

Results

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.

Conclusions

We found increased risk of GI at this urban聽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聽associations were seen. These different relationships under different conditions at a single beach demonstrate the difficulties using these indicators to predict health risk.