Use of a Gamma-IFN Assay in Contact Tracing for Tuberculosis in a Low-Incidence, High Immigration Area
After exposure to an active case of tuberculosis (TB), close contacts may be infected. They are then considered as having latent tuberculosis infection (LTBI). Detecting LTBI is the main goal of contact tracing procedures after exposure to TB. Until recently, the only test available for detecting LTBI was the tuberculin skin test (TST). More recent tests are now available (Interferon-gamma release assays: IGRA), which are more specific and sensitive than the TST. This study compares the TST and an IGRA in the routine activity of contact tracing in our area.
Latent Tuberculosis Infection
|Study Design:||Observational Model: Case-Only
Time Perspective: Prospective
|Official Title:||Production of Gamma-Interferon by Circulating Lymphocytes Exposed to Antigens Specific of Mycobacterium Tuberculosis: Contribution to the Identification of Latent Tuberculosis Infection in Contact Tracing|
- Correlation between results of TST and IGRA tests and exposure scores [ Time Frame: 2 months after exposure ]
|Study Start Date:||October 2004|
|Study Completion Date:||January 2006|
Setting: A TB clinic in Geneva, Switzerland, a low incidence area for TB with a high immigrant population.
Aim of study: to compare results of an IGRA test (T-SPOT.TB, Oxford Immunotec, UK) and the TST, and their correlation with exposure scores in subjects exposed to cases of contagious TB.
Methods: Prospective study of all contacts screened in our area, and accepting to be included. Simultaneous recording of age, gender, origin, history of recent travels or exposure, BCG vaccination status, infectiousness of index case, 5 different exposure scores, TST, and result of the T-SPOT.TB blood test. Univariate and multivariate analysis.
|Centre antituberculeux; Geneva University Hospital|
|Geneva, Switzerland, 1211|
|Principal Investigator:||Jean-Paul Janssens, M.D.||Centre antituberculeux|