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Table 2 Summary statistics of outbreak and endemic cases of tuberculosis due to RFLP types 0.0142 and 0.0728 in Alberta First Nations communities, 1991–2013

From: Epidemiological and genomic determinants of tuberculosis outbreaks in First Nations communities in Canada

 

Group 1a (n = 2)

Group 1b (n = 27)

Group 2a (n = 15)

Group 2b (n = 31)

Age, years

 Mean (standard deviation)

25 (4.2)

21.4 (15.9)

37.7 (13.4)

44.4 (21.9)

 Median

25

21

44

40

 Minimum to maximum

22–28

0–59

18–56

1–92

Percentage of cases with cavitation on chest radiograph

100

0

57.1#

3.3

Number of total contacts per case

 Mean

811.5§

3.2

106

18.5

 Median

811.5

0

51

6

 Minimum to maximum

488–1135

0–34

10–672

0–189

 75% –25% interquartile range

647

1

79

9

Number of close contacts per case

 Mean

72§

1.9

47.7

9.4

 Median

72

0

17

5

 Minimum to maximum

69–75

0–18

0–465

0–80

 75% – 25% interquartile range

6

0

29

10

Number of child-age† contacts per case

 Mean

27

0.7

3.9

2.2

 Median

27

0

2

1

 Minimum to maximum

26–28

0–8

0–23

0–17

 75% – 25% interquartile range

2

0

5

3

Number of new TST positive tests among contacts

 Mean

15.5

0.2

1.8

0.3

 Median

15.5

0

1

0

 Minimum to maximum

13–18

0–2

0–13

0–2

 75% – 25% interquartile range

5

0

2

0

Number of TST conversions among contacts

 Mean

14.5

0.1

1.9

0.3

 Median

14.5

0

1

0

 Minimum to maximum

12–17

0–2

0–20

0–1

 75% – 25% interquartile range

5

0

1

0

Percentage of diagnoses made during cold season

100

92.5

46.7

38.7

Percentage of cases living on reserve

100

25.9

73.3

48.4

  1. #Adjusted for one missing value
  2. †Children were defined as being aged under 15 years
  3. §An entire community was screened as part of the contact investigation in one of the outbreaks described
  4. RFLP restriction fragment-length polymorphism, TST tuberculin skin test