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Table 3 Modification of the association between Enterococcus (CCE/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)

Gastrointestional illness b

–

 

1.4% (0.6%, 2.3%)

 

HumM2

0–1

4.4

Ref

 
 

6.3

1.8% (1.0%, 2.7%)

 

≥2

5.9

Ref

 
 

6.9

1.0% (−0.5%, 2.4%)

−0.9% (−2.3%, 0.6%)

HF183

0–1

4.4

Ref

 
 

6.1

1.7% (0.6%, 2.7%)

 

≥2

5.7

Ref

 
 

6.9

1.3% (0.2%, 2.4%)

−0.4% (−1.7%, 0.9%)

BsteriF1

0–1

7.2

Ref

 
 

7.2

0.0% (−3.7%, 3.7%)

 

≥2

5.6

Ref

 
 

7.0

1.4% (0.4%, 2.4%)

1.4% (−2.4%, 5.1%)

BuniF2

0–1

1.1

Ref

 
 

2.5

1.5% (0.4%, 2.5%)

 

≥2

5.7

Ref

 
 

7.0

1.3% (0.3%, 2.3%)

−0.2% (−1.5%, 1.1%)

Diarrhea b

–

 

1.1% (0.6%, 1.7%)

 

HumM2

   

0–1

2.6

Ref

 
 

4.0

1.4% (0.9%, 1.9%)

 

≥2

3.3

Ref

 
 

4.2

0.9% (0.0%, 1.8%)

−0.5% (−1.4%, 0.4%)

HF183

0–1

3.6

Ref

 
 

4.8

1.2% (0.1%, 2.3%)

 

≥2

2.7

Ref

 
 

3.9

1.2% (0.7%, 1.7%)

0.0% (−1.1%, 1.1%)

BsteriF1

0–1

5.5

Ref

 
 

5.2

−0.3% (−4.0%, 3.5%)

 

≥2

3.0

Ref

 
 

4.2

1.2% (0.7%, 1.7%)

1.5% (−2.3%, 5.2%)

BuniF2

0–1

0.9

Ref

 
 

2.1

1.2% (0.3%, 2.1%)

 

≥2

3.2

Ref

 
 

4.3

1.1% (0.5%, 1.7%)

−0.1% (−1.1%, 0.9%)

Respiratory Illness c

–

 

0.6% (−0.7%, 1.8%)

 

HumM2

0–1

6.4

Ref

 
 

6.4

0.0% (−2.0%, 2.0%)

 

≥2

4.6

Ref

 
 

5.6

1.0% (−0.4%, 2.3%)

0.9% (−1.2%, 3.1%)

HF183

0–1

13.9

Ref

 
 

9.5

−4.4% (−10.8%, 2.0%)

 

≥2

3.9

Ref

 
 

5.1

1.3% (0.4%, 2.1%)

5.7% (−0.7%, 12%)

BsteriF1

0–1

8.7

Ref

 
 

6.7

−1.9% (−7.8%, 4.0)

 

≥2

5.7

Ref

 
 

6.2

0.5% (−0.9%, 1.9%)

2.5% (−3.3%, 8.3%)

BuniF2

   

0–1

1.5

Ref

 
 

2.7

1.2% (0.7%, 1.8%)

 

≥2

5.6

Ref

 
 

6.1

0.5% (−0.9%, 1.8%)

−0.8% (−2.1%, 0.5%)

  1. Abbreviations: CCE calibrator cell equivalents, CI confidence interval, RD risk difference, Ref reference
  2. a Enterococcus exposure measured by qPCR and coded continuously as an average log10 count of Enterococcus CCE/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