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Table 4 Modification of the association between Enterococcus (CFU/100 ml) exposurea and illness with human-associated Bacteroides markers, all beaches

From: Exposure to human-associated fecal indicators and self-reported illness among swimmers at recreational beaches: a cohort study

Marker (samples)

Adjusted risk (%)

Adjusted RD (95% CI)

Interaction contrast (95% CI)

Gastrointestinal Illness b

–

 

−0.1% (−1.5%, 1.2%)

 

HumM2

0–1

8.0

Ref

 
 

8.4

0.4% (−1.5%, 2.3%)

 

≥2

8.7

Ref

 
 

8.3

−0.3% (−2.1%, 1.4%)

−0.8% (−3.1%, 1.6%)

HF183

0–1

6.6

Ref

 
 

8.0

1.4% (−0.5%, 3.2%)

 

≥2

10.0

Ref

 
 

8.8

−1.1% (−3.1%, 0.9%)

−2.5% (−5.1%, 0.2%)

BsteriF1

0–1

5.3

Ref

 
 

6.9

1.6% (−0.6%, 3.8%)

 

≥2

9.9

Ref

 
 

8.9

−1.0% (−2.7%, 0.8%)

−2.6% (−5.4%, 0.2%)

Bunif2

0–1

3.2

Ref

 
 

6.2

3.1% (0.9%, 5.2%)

 

≥2

9.2

Ref

 
 

8.6

−0.6% (−2.1%, 0.9%)

−3.6% (−6.2%, −1.1%)

Diarrhea b

–

 

0.2% (−0.8%, 1.2%)

 

HumM2

0–1

4.8

Ref

 
 

5.6

0.8% (−0.6%, 2.2%)

 

≥2

5.4

Ref

 
 

5.4

0.1% (−1.2%, 1.3%)

−0.7% (−2.5%, 1.0%)

HF183

0–1

4.7

Ref

 
 

5.8

1.1% (−0.4%, 2.7%)

 

≥2

5.8

Ref

 
 

5.6

−0.2% (−1.5%, 1.2%)

−1.3% (−3.3%, 0.7%)

BsteriF1

0–1

3.2

Ref

 
 

4.7

1.5% (−0.3%, 3.2%)

 

≥2

6.3

Ref

 
 

6.0

−0.4% (−1.7%, 1.0%)

−1.8% (−4.0%, 0.3%)

Bunif2

0–1

2.1

Ref

 
 

4.6

2.5% (0.8%, 4.2%)

 

≥2

5.8

Ref

 
 

5.7

−0.1% (−1.2%, 1.0%)

−2.6% (−4.6%, −0.6%)

Respiratory Illness c

–

 

−0.6% (−2.1%, 0.9%)

 

HumM2

0–1

7.3

Ref

 
 

6.5

−0.8% (−2.6%, 1.0%)

 

≥2

7.4

Ref

 
 

6.8

−0.6% (−2.7%, 1.5%)

0.2% (−2.3%, 2.7%)

HF183

0–1

7.6

Ref

 
 

6.1

−1.4% (−3.7%, 0.9%)

 

≥2

7.2

Ref

 
 

6.8

−0.4% (−2.3%, 1.5%)

1.0% (−2.0%, 3.9%)

BsteriF1

0–1

5.5

Ref

 
 

5.3

−0.1% (−2.4%, 2.1%)

 

≥2

8.4

Ref

 
 

7.1

−1.3% (−3.4%, 0.9%)

−1.1% (−4.2%, 2.0%)

Bunif2

0–1

3.2

Ref

 
 

5.2

2.1% (0.1%, 4.1%)

 

≥2

7.8

Ref

 
 

6.8

−1.0% (−2.7%, 0.7%)

−3.1% (−5.7%, −0.4%)

  1. Abbreviations: CFU colony forming units, CI confidence interval, RD risk difference, Ref reference
  2. a Enterococcus exposure measured by culture Method 1600 and coded continuously as an average log10 count of Enterococcus CFU/100 ml per day
  3. b Adjusted for beach, age, mean bathers, sand, rainfall since 3 pm the previous day, water temperature
  4. c Adjusted for beach, age, mean bathers, sand, rainfall since 3 pm the previous day
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Environmental Health

ISSN: 1476-069X