title: TB incidence in an adolescent cohort in South Africa.
abstract: BACKGROUND
  Tuberculosis (TB) is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa.
  
  
  METHODS
  We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST) performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment.
  
  
  RESULTS
  A total of 6,363 adolescents were enrolled (58% of the school population targeted). During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.29-0.72). Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis.
  
  
  CONCLUSIONS
  The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease.
authors.affiliation: South African Tuberculosis Vaccine Initiative, Institute of Infectious Disease and Molecular Medicine, Cape Town, South Africa. hmahomed799@gmail.com
authors.forename: Hassan
authors.initials: H
authors.lastname: Mahomed
authors.forename: Rodney
authors.initials: R
authors.lastname: Ehrlich
authors.forename: Tony
authors.initials: T
authors.lastname: Hawkridge
authors.forename: Mark
authors.initials: M
authors.lastname: Hatherill
authors.forename: Lawrence
authors.initials: L
authors.lastname: Geiter
authors.forename: Fazlin
authors.initials: F
authors.lastname: Kafaar
authors.forename: Deborah Ann
authors.initials: DA
authors.lastname: Abrahams
authors.forename: Humphrey
authors.initials: H
authors.lastname: Mulenga
authors.forename: Michele
authors.initials: M
authors.lastname: Tameris
authors.forename: Hennie
authors.initials: H
authors.lastname: Geldenhuys
authors.forename: Willem Albert
authors.initials: WA
authors.lastname: Hanekom
authors.forename: Suzanne
authors.initials: S
authors.lastname: Verver
authors.forename: Gregory Dudley
authors.initials: GD
authors.lastname: Hussey
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology*