title: Using rapid indicators for Enterococcus to assess the risk of illness after exposure to urban runoff contaminated marine water.
abstract: BACKGROUND
  Traditional fecal indicator bacteria (FIB) measurement is too slow (>18 h) for timely swimmer warnings.
  
  
  OBJECTIVE
  Assess relationship of rapid indicator methods (qPCR) to illness at a marine beach impacted by urban 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™, 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 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.
authors.affiliation: University of California Berkeley, School of Public Health, 101 Haviland, MC# 7358, Berkeley, CA 94720-7358, USA. jcolford@berkeley.edu
authors.forename: John M
authors.initials: JM
authors.lastname: Colford
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Schiff
authors.forename: John F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Vince
authors.initials: V
authors.lastname: Yau
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Arnold
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Wright
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Gruber
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wade
authors.forename: Susan
authors.initials: S
authors.lastname: Burns
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Hayes
authors.forename: Charles
authors.initials: C
authors.lastname: McGee
authors.forename: Mark
authors.initials: M
authors.lastname: Gold
authors.forename: Yiping
authors.initials: Y
authors.lastname: Cao
authors.forename: Rachel T
authors.initials: RT
authors.lastname: Noble
authors.forename: Richard
authors.initials: R
authors.lastname: Haugland
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Weisberg
mesh_terms: D001493:Bathing Beaches / Q000592:standards*; D002140:California / Q000453:epidemiology; D003114:Colony-Forming Units Assay; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology; D016983:Enterococcus / Q000235:genetics* / Q000254:growth & development; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000382:microbiology*; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D016017:Odds Ratio; D016133:Polymerase Chain Reaction; D012623:Seawater / Q000737:chemistry*; D014876:Water Pollution / Q000009:adverse effects / Q000032:analysis*