title: Incidence of tuberculosis among children living in contact with smear-positive tuberculosis: Advantages and limits of the Quantiferon TB gold in tube test.
abstract: OBJECTIVE
  Children living in contact with smear-positive pulmonary tuberculosis (TB) patients are highly exposed to TB infection. Our objective was to estimate the incidence of TB in children living in contact with a Smear Positive (M+) pulmonary tuberculosis (PTM+) index case during 2years following exposure.
  
  
  METHODS
  This was a descriptive, cohort, prospective, multicenter study of children aged from 6months to 15years in contact with a PTM+ case. The recruitment of children has been based on the diagnosed PTM+ index case and taken in charge by the Services of Control of Tuberculosis and Respiratory Diseases located in Algiers during 2014. Seven centers were selected. All children were tested using the Quantiferon TB gold in tube (QTR) test and the tuberculin skin test (TST). For TST, an induration diameter ⩾10mm was considered positive.
  
  
  RESULTS
  We included 456 children living in contact with a PTM+ patient. The results for TST and QFT were available for 319 children. The mean age of the children was 6.7years (standard deviation=3.9). The sex ratio (Male/Female) was 1.26, and 15.8% (50) did not have a Bacilli of Calmette & Guerin (BCG) vaccination scar. Among the children, 46.1% (147) and 43.4% (138) were positive for QFT and TST, respectively, and 6.1% (19) have received isoniazid preventive therapy. Fifty-one children progressed to TB and received antitubercular treatment. We analyzed and compared our results between children who progressed to TB and those who did not progress to TB. Finally, we discuss our methodology and results in relation to the literature.
authors.affiliation: Service d'Épidémiologie, Institut National de Santé Publique, Algiers, Algeria.
authors.forename: Djohar
authors.initials: D
authors.lastname: Hannoun
authors.affiliation: Laboratoire National de Référence pour la Tuberculose, Institut Pasteur d'Algérie, Algiers, Algeria. Electronic address: fadiboulboul@yahoo.fr.
authors.forename: Fadila
authors.initials: F
authors.lastname: Boulahbal
keywords: Childhood tuberculosis; Index case; Latent tuberculosis; Quantiferon test; Tuberculin skin test