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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