title: Tuberculosis in children exposed at home to multidrug-resistant tuberculosis.
abstract: BACKGROUND
  The tuberculosis burden in children exposed at home to multidrug-resistant tuberculosis (MDR-TB) is unquantified. With limited access to MDR-TB treatment, likely millions of children share the experience of chronic exposure to an infectious patient.
  
  
  METHODS
  We conducted a retrospective cohort study of child and adult household contacts of patients treated for MDR-TB in Lima, Peru, in 1996 to 2003. The primary outcome was TB disease. We estimated prevalence of TB disease when the index case began MDR-TB treatment and incidence of TB disease over the subsequent 4 years.
  
  
  RESULTS
  Among 1299 child contacts, 67 were treated for TB. TB prevalence was 1771 (confidence interval [CI]: 1052-2489) per 100,000 children. In 4362 child-years of follow-up, TB incidence rates per 100,000 child-years were: 2079 (CI: 1302-2855) in year 1; 315 (CI: 6-624) in year 2; 634 (CI: 195-1072) in year 3; and 530 (CI: 66-994) in year 4. TB disease rates in children aged >1 year were not significantly different from those observed in adults. Children accounted for 20% of TB cases. Seven (87.5%) of 8 children tested had MDR-TB. Child contacts had TB disease rates approximately 30 times higher than children in the general population.
  
  
  CONCLUSIONS
  Children were at high risk for TB disease when the index case started MDR-TB treatment and during the following year. These results highlight the need for implementing contact investigations and establishing systems for prompt referral and treatment of pediatric household contacts of MDR-TB patients, regardless of the age of the child.
authors.affiliation: Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA. mbecerra@post.harvard.edu
authors.forename: Mercedes C
authors.initials: MC
authors.lastname: Becerra
authors.forename: Molly F
authors.initials: MF
authors.lastname: Franke
authors.forename: Sasha C
authors.initials: SC
authors.lastname: Appleton
authors.forename: J Keith
authors.initials: JK
authors.lastname: Joseph
authors.forename: Jaime
authors.initials: J
authors.lastname: Bayona
authors.forename: Sidney S
authors.initials: SS
authors.lastname: Atwood
authors.forename: Carole D
authors.initials: CD
authors.lastname: Mitnick
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing; D024901:Drug Resistance, Multiple, Bacterial; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005191:Family Characteristics; D005260:Female; D005838:Genotype; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology* / Q000382:microbiology