title: QuantiFERON-TB Gold test in the identification of latent tuberculosis infection in immigrants.
abstract: BACKGROUND
  The identification and treatment of latent tuberculosis infection (LTBI) among immigrants are an effective strategy for TB control in developed countries. A new test for LTBI identification that uses more specific antigens of Mycobacterium tuberculosis is now commercially available under the brand name of QuantiFERON-TB Gold test.
  
  
  OBJECTIVE
  To compare QuantiFERON-TB Gold test to tuberculin skin testing (TST) for the detection of LTBI among immigrants from high endemic TB areas.
  
  
  METHODS
  Undocumented immigrants attending a district medical center were enrolled if they originated from high endemic TB areas, the time of arrival in Italy was < or = 5 years, had neither active TB disease nor known immunodeficiency status. The TST was applied according to standards and QuantiFERON-TB Gold test was performed following the manufacturer's instructions.
  
  
  RESULTS
  Hundred subjects were included in the comparative analysis. TST was positive in 44% of subjects; 15% had a positive QuantiFERON-TB Gold test result. The total agreement between TST and QuantiFERON-TB Gold test was 71%, for a kappa statistics of 0.37; agreement was 100% for TST negative results, but only 34% for TST positive ones. In the multivariate logistic regression analysis, previous BCG vaccination was independently associated with a lower chance of disagreement between the tests.
  
  
  CONCLUSIONS
  The prevalence of LTBI among immigrants was lower when determined by QuantiFERON-TB Gold; this may be a consequence of more specific MTB antigens used. Our results suggest that QuantiFERON-TB Gold may be used as confirmatory test for TST positive immigrants candidate to preventive therapy.
authors.affiliation: Institute of Infectious and Tropical Diseases, University of Brescia, Piazza Spedali Civili 1, 25125 Brescia, Italy. a.carvalho@libero.it
authors.forename: Anna C C
authors.initials: AC
authors.lastname: Carvalho
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Pezzoli
authors.forename: Issa
authors.initials: I
authors.lastname: El-Hamad
authors.forename: Patricia
authors.initials: P
authors.lastname: Arce
authors.forename: Sara
authors.initials: S
authors.lastname: Bigoni
authors.forename: Carmelo
authors.initials: C
authors.lastname: Scarcella
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Indelicato
authors.forename: Carla
authors.initials: C
authors.lastname: Scolari
authors.forename: Giampiero
authors.initials: G
authors.lastname: Carosi
authors.forename: Alberto
authors.initials: A
authors.lastname: Matteelli
mesh_terms: D000328:Adult; D004641:Emigration and Immigration / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012882:Skin Tests; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D011933:Reagent Kits, Diagnostic