The Effectiveness of Using Interferon-gamma Release Assays in Screening Immigration Employees for Latent Tuberculosis Infection

Abstract

We assessed the prevalence of latent tuberculosis infection in immigration employees and compared two of the screening methods. Using a cross-sectional study design, we administered questionnaires regarding demographics, work, medical history, and tuberculosis risk factors to employees at two immigration facilities. Participants underwent tuberculin skin test (TST) placement and blood collection for the QuantiFERON-TB Gold in-Tube (QFT-GIT) assay. Fifty-four employees underwent QFT-GIT and TST placement. All QFT-GIT results were negative, and three employees tested TST positive. Twenty-three (49%) of 47 employees requiring two-step TST testing underwent second TST placement. Return rates for first and second TST reading were 76% and 74%, respectively. The QFT-GIT completion rate was higher than that for TST (100% vs. 39%, P < 0.001). Agreement between TST and QFT-GIT was 94%. Immigration employees had low return rates for their TST reading and second TST placement. Performing the one-visit QFT-GIT has administrative and logistical advantages in this occupational group.