title: Contact investigation based on serial interferon-gamma release assays (IGRA) in children from the hematology-oncology ward after exposure to a patient with pulmonary tuberculosis.
abstract: BACKGROUND
  Interferon-gamma release assays (IGRAs) have high specificity and sensitivity for the diagnosis of tuberculosis (TB) infection. However, their role as a screening tool in children with immunodeficiency disorders is still unclear. In the present study, we performed a contact investigation using serial IGRAs on children with immunodeficiency conditions exposed to a contagious TB patient.
  
  
  METHODS
  Children who were exposed to a contagious TB case underwent serial QuantiFERON(®) TB Gold In-Tube (QFT-GIT) and T-SPOT(®).TB (T-SPOT) testing.
  
  
  RESULTS
  Eighteen children were tested. At the first testing, only two children (11 %) were positive to T-SPOT. Indeterminate results were more frequent with QFT-GIT (35 %) than with T-SPOT (12 %). In the multivariable analysis, a statistically significant association of lymphocyte count <500 cells/mm(3) (p < 0.00005) and low age (p = 0.03) with indeterminate results for the QFT-GIT test but not for T-SPOT (p = 0.10 and p = 0.88, respectively) was found. At the end of October 2012, 15 of the 18 children were alive and none developed active TB disease.
  
  
  CONCLUSIONS
  T-SPOT provided more determinate results and was less influenced by low age and lymphocytopenia than QFT-GIT in this population of immunodeficient children. These findings suggest that T-SPOT is a more accurate test for the identification of TB infection in young children with lymphocytopenia and should be preferred to QFT-GIT under such specific conditions.
authors.affiliation: Institute of Infectious and Tropical Diseases, University of Brescia, Spedali Civili di Brescia, Piazza Spedali Civili di Brescia 1, 25125, Brescia, Italy. a.carvalho@libero.it
authors.forename: A C C
authors.initials: AC
authors.lastname: Carvalho
authors.forename: R F
authors.initials: RF
authors.lastname: Schumacher
authors.forename: S
authors.initials: S
authors.lastname: Bigoni
authors.forename: E
authors.initials: E
authors.lastname: Soncini
authors.forename: L
authors.initials: L
authors.lastname: Notarangelo
authors.forename: A
authors.initials: A
authors.lastname: Apostoli
authors.forename: C
authors.initials: C
authors.lastname: Bonfanti
authors.forename: D
authors.initials: D
authors.lastname: Cirillo
authors.forename: P
authors.initials: P
authors.lastname: Mantegani
authors.forename: F
authors.initials: F
authors.lastname: Porta
authors.forename: M
authors.initials: M
authors.lastname: Comelli
authors.forename: A
authors.initials: A
authors.lastname: Matteelli
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing / Q000379:methods*; D003428:Cross Infection / Q000175:diagnosis / Q000635:transmission; D005260:Female; D019337:Hematologic Neoplasms / Q000150:complications; D006801:Humans; D007223:Infant; D059425:Interferon-gamma Release Tests / Q000379:methods*; D008297:Male; D008403:Mass Screening / Q000379:methods; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000635:transmission*; D055815:Young Adult