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Table 2 Risk factors for influenza and RSV infection among participants with influenza-like illness in Macha, Zambia

From: Facility-based surveillance for influenza and respiratory syncytial virus in rural Zambia

 

Total n = 671

Influenza A n = 86

Influenza B n = 36

RSV n = 76

Prevalencea

Univariable prevalence ratio (95% CI)

Age-adjusted prevalence ratio (95% CI)

Prevalencea

Univariable prevalence ratio (95% CI)

Age-adjusted prevalence ratio (95% CI)

Prevalencea

Univariable prevalence ratio (95% CI)

Age-adjusted prevalence ratio (95% CI))

Sociodemographic characteristics and household exposures

 Age, years

  Per year increase

  

1.00 (0.99–1.01)

–

 

0.97 (0.95–1.00)

–

 

0.94 (0.91–0.97)

–

  0–5 months

72

7 (10%)

Ref

–

4 (6%)

Ref

–

14 (19%)

Ref

–

  6–11 months

115

6 (5%)

0.54 (0.19–1.53)

–

2 (2%)

0.31 (0.06–1.67)

–

16 (14%)

0.72 (0.37–1.38)

–

  1–4

212

37 (17%)

1.80 (0.84–3.85)

–

14 (7%)

1.19 (0.40–3.50)

–

35 (17%)

0.85 (0.49–1.49)

–

  5–15

86

17 (20%)

2.03 (0.89–4.63)

–

12 (14%)

2.51 (0.85–7.45)

–

8 (9%)

0.48 (0.21–1.08)

–

  16–50

109

10 (9%)

0.94 (0.38–2.37)

–

4 (4%)

0.66 (0.17–2.56)

–

2 (2%)

0.09 (0.02–0.40)

–

  51+

77

9 (12%)

1.20 (0.47–3.06)

–

0 (0%)

N/A

–

1 (1%)

0.07 (0.01–0.50)

–

 Patient type (n,%)

  Outpatient

576

66 (11%)

Ref

Ref

34 (6%)

Ref

Ref

61 (11%)

Ref

Ref

  Inpatient

95

20 (21%)

1.84 (1.17–2.88)

1.86 (1.19–2.89)

2 (2%)

0.36 (0.09–1.46)

0.38 (0.09–1.56)

15 (16%)

1.49 (0.89–2.51)

1.54 (0.93–2.56)

 Sex (n,%)

  Male

311

44 (14%)

Ref

Ref

11 (4%)

Ref

Ref

41 (13%)

Ref

Ref

  Female

360

42 (12%)

0.82 (0.56–1.22)

0.81 (0.55–1.20)

11 (4%)

1.96 (0.98–3.93)

1.95 (0.98–3.90)

41 (13%)

0.74 (0.48–1.13)

0.86 (0.56–1.31)

 Recent travel outside district (n, %)

  No

636

79 (12%)

Ref

Ref

34 (5%)

Ref

Ref

76 (12%)

Ref

Ref

  Yes

34

7 (21%)

1.66 (0.83–3.31)

2.35 (1.14–4.84)

2 (6%)

1.10 (0.28–4.39)

1.77 (0.42–7.48)

0 (0%)

N/A

N/A

 Symptomatic contact in household (n,%)

  No

328

32 (10%)

Ref

Ref

14 (4%)

Ref

Ref

28 (9%)

Ref

Ref

  Yes

337

52 (15%)

1.58 (1.05–2.39)

1.54 (1.02–2.31)

22 (7%)

1.53 (0.80–2.94)

1.51 (0.80–2.88)

48 (14%)

1.67 (1.07–2.59)

1.57 (1.02–2.43)

 Indoor cooking (n,%)

  No

616

82 (13%)

Ref

Ref

30 (5%)

Ref

Ref

66 (11%)

Ref

Ref

  Yes

55

4 (7%)

0.55 (0.21–1.43)

0.52 (0.20–1.36)

6 (11%)

2.24 (0.97–5.15)

1.89 (0.83–4.28)

10 (18%)

1.70 (0.93–3.11)

2.00 (1.12–3.56)

 Current smoker or smoker in household (n,%)

  No

547

68 (12%)

Ref

Ref

33 (6%)

Ref

Ref

64 (12%)

Ref

Ref

  Yes

124

18 (15%)

1.17 (0.72–1.89)

1.19 (0.74–1.91)

3 (2%)

0.40 (0.12–1.29)

0.39 (0.12–1.25)

12 (10%)

0.83 (0.46–1.48)

0.85 (0.48–1.50)

 Number of individuals sharing sleeping space

  Per person increase

3 (2–3)

3 (2–3)

0.93 (0.75–1.14)

0.89 (0.71–1.13)

3 (2–3)

1.11 (0.84–1.46)

1.02 (0.74–1.39)

3 (3–3)

1.14 (0.98–1.33)

1.00 (0.81–1.24)

  1

29

3 (10%)

Ref

Ref

0 (0%)

Ref

Ref

0 (0%)

Ref

Ref

  2–3

512

69 (13%)

1.30 (0.44–3.89)

1.21 (0.39–3.73)

28 (5%)

N/A

N/A

58 (11%)

N/A

N/A

  4+ 

130

14 (11%)

1.04 (0.32–3.39)

1.28 (0.30–5.54)

8 (6%)

N/A

N/A

18 (14%)

N/A

N/A

 Food insecurity (n,%)

  No

652

85 (13%)

Ref

Ref

36 (6%)

Ref

Ref

75 (12%)

Ref

Ref

  Yes

19

1 (5%)

0.40 (0.06–2.75)

0.51 (0.08–3.45)

0 (0%)

N/A

N/A

1 (5%)

0.46 (0.07–3.12)

0.60 (0.09–3.93)

 Recent animal exposureb (n,%)

  No

555

67 (12%)

Ref

Ref

30 (5%)

Ref

Ref

67 (12%)

Ref

Ref

  Yes

112

17 (15%)

1.26 (0.77–2.06)

1.16 (0.71–1.92)

6 (5%)

0.99 (0.42–2.32)

0.90 (0.38–2.12)

9 (8%)

0.67 (0.34–1.30)

0.98 (0.51–1.92)

Medical history

 Underweight (n,%)

  No

601

71 (12%)

Ref

Ref

33 (5%)

Ref

Ref

69 (11%)

Ref

Ref

  Yes

68

14 (21%)

1.74 (1.04–2.92)

1.72 (1.04–2.87)

3 (4%)

0.80 (0.25–2.55)

0.99 (0.32–3.10)

6 (9%)

0.77 (0.35–1.70)

0.96 (0.44–2.08)

HIV-infected (n,%)

  No

639

83 (13%)

Ref

Ref

36 (6%)

Ref

Ref

76 (12%)

Ref

Ref

  Yes

29

3 (10%)

0.80 (0.27–2.37)

0.97 (0.31–3.01)

0 (0%)

N/A

N/A

0 (0%)

N/A

N/A

 History of tuberculosis (n,%)

  No

649

85 (13%)

Ref

Ref

36 (6%)

Ref

Ref

76 (12%)

Ref

Ref

  Yes

22

1 (5%)

0.35 (0.05–2.38)

0.39 (0.06–2.80)

0 (0%)

N/A

N/A

0 (0%)

N/A

N/A

 History of chronic cardiovascular or pulmonary disease (n,%)

  No

637

83 (13%)

Ref

Ref

36 (6%)

Ref

Ref

76 (12%)

Ref

Ref

  Yes

34

3 (9%)

0.68 (0.23–2.03)

0.73 (0.22–2.43)

0 (0%)

N/A

N/A

0 (0%)

N/A

N/A

 Anemia (n,%)

  No

650

84 (13%)

Ref

Ref

36 (6%)

Ref

Ref

73 (11%)

Ref

Ref

  Yes

21

2 (10%)

0.74 (0.19–2.80)

0.77 (0.20–2.92)

0 (0%)

N/A

N/A

3 (14%)

1.27 (0.44–3.71)

2.21 (0.82–5.92)

  1. aPercentages represent row totals (i.e. the total number with a given attribute within each infection group divided by the total number with a given attribute)
  2. bRecent animal contact is defined as handling or feeding in the 5 days preceding hospital presentation; includes contact with whole animal carcass but not with processed meat
  3. CI, Confidence interval; N/A, Not available; REF, Reference group; Bold = p < 0.05 from log-binomial regression
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BMC Infectious Diseases

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