title: Risk factors for Mycobacterium tuberculosis infection among children in Greenland.
abstract: OBJECTIVE
  To examine the risk factors for Mycobacterium tuberculosis infection (MTI) among Greenlandic children for the purpose of identifying those at highest risk of infection.
  
  
  METHODS
  Between 2005 and 2007, 1797 Greenlandic schoolchildren in five different areas were tested for MTI with an interferon gamma release assay (IGRA) and a tuberculin skin test (TST). Parents or guardians were surveyed using a standardized self-administered questionnaire to obtain data on crowding in the household, parents' educational level and the child's health status. Demographic data for each child--i.e. parents' place of birth, number of siblings, distance between siblings (next younger and next older), birth order and mother's age when the child was born--were also extracted from a public registry. Logistic regression was used to check for associations between these variables and MTI, and all results were expressed as odds ratios (ORs) and 95% confidence intervals (CIs). Children were considered to have MTI if they tested positive on both the IGRA assay and the TST.
  
  
  RESULTS
  The overall prevalence of MTI was 8.5% (152/1797). MTI was diagnosed in 26.7% of the children with a known TB contact, as opposed to 6.4% of the children without such contact. Overall, the MTI rate was higher among Inuit children (OR:  4.22; 95% CI: 1.55-11.5) and among children born less than one year after the birth of the next older sibling (OR:  2.48; 95% CI: 1.33-4.63). Self-reported TB contact modified the profile to include household crowding and low mother's education. Children who had an older MTI-positive sibling were much more likely to test positive for MTI themselves (OR:  14.2; 95% CI: 5.75-35.0) than children without an infected older sibling.
  
  
  CONCLUSIONS
  Ethnicity, sibling relations, number of household residents and maternal level of education are factors associated with the risk of TB infection among children in Greenland. The strong household clustering of MTI suggests that family sources of exposure are important.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark. bot@ssi.dk
authors.forename: Bolette
authors.initials: B
authors.lastname: Søborg
authors.forename: Aase Bengaard
authors.initials: AB
authors.lastname: Andersen
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Mikael
authors.initials: M
authors.lastname: Andersson
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Biggar
authors.forename: Karin
authors.initials: K
authors.lastname: Ladefoged
authors.forename: Vibeke Ostergaard
authors.initials: VO
authors.lastname: Thomsen
authors.forename: Anders
authors.initials: A
authors.lastname: Koch
mesh_terms: D000293:Adolescent; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D016001:Confidence Intervals; D005260:Female; D006116:Greenland / Q000453:epidemiology; D006304:Health Status; D054624:Health Status Disparities; D006801:Humans; D059425:Interferon-gamma Release Tests; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D016017:Odds Ratio; D010372:Pediatrics; D015995:Prevalence; D011634:Public Health / Q000639:trends*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult
references.citation: Am Rev Respir Dis. 1967 Nov;96(5):885-92
references.pmid: 6059198
references.citation: Eur Respir J. 2010 Aug;36(2):355-61
references.pmid: 19926734
references.citation: Pediatr Infect Dis J. 2005 Aug;24(8):743-4
references.pmid: 16094237
references.citation: Lancet. 2003 May 31;361(9372):1871-2
references.pmid: 12788577
references.citation: Bull Int Union Tuberc. 1975;50(1):70-81
references.pmid: 1218289
references.citation: Emerg Infect Dis. 2008 Jan;14(1):56-9
references.pmid: 18258077
references.citation: Eur Respir J. 2010 Oct;36(4):878-84
references.pmid: 20516050
references.citation: Int J Circumpolar Health. 2011 Apr;70(2):128-40
references.pmid: 21524358
references.citation: Tubercle. 1976 Dec;57(4 Suppl):S1-58
references.pmid: 797076
references.citation: Can Respir J. 2000 Mar-Apr;7(2):141-6
references.pmid: 10859400
references.citation: Clin Exp Allergy. 2002 Mar;32(3):367-72
references.pmid: 11940065
references.citation: Am J Respir Crit Care Med. 2003 Dec 1;168(11):1353-7
references.pmid: 14500266
references.citation: Am J Respir Crit Care Med. 2006 Aug 1;174(3):339-43
references.pmid: 16690980
references.citation: Lancet. 2000 Jan 29;355(9201):358-62
references.pmid: 10665555
references.citation: BMC Infect Dis. 2009 Jun 17;9:96
references.pmid: 19534769
references.citation: Tubercle. 1983 Dec;64(4):241-53
references.pmid: 6606884
references.citation: Am Psychol. 1994 Jan;49(1):15-24
references.pmid: 8122813
references.citation: Int J Tuberc Lung Dis. 2001 Mar;5(3):257-65
references.pmid: 11326825
references.citation: N Engl J Med. 1999 Nov 11;341(20):1491-5
references.pmid: 10559449
references.citation: Soc Sci Med. 2009 Jun;68(12):2240-6
references.pmid: 19394122
references.citation: Int J Tuberc Lung Dis. 2003 Dec;7(12 Suppl 3):S349-52
references.pmid: 14677821
references.citation: Dan Med Bull. 2006 Nov;53(4):441-9
references.pmid: 17150149
references.citation: Am J Public Health. 2005 May;95(5):873-80
references.pmid: 15855468
references.citation: Helicobacter. 2005 Oct;10(5):433-42
references.pmid: 16181354
references.citation: Int J Tuberc Lung Dis. 2011 Jan;15(1):44-9
references.pmid: 21276295
references.citation: J Infect Dis. 2003 Sep 1;188(5):777-82
references.pmid: 12934195