Diagnosis and treatment of latent tuberculosis infection: an update.

It is estimated that more than two billion people have latent M. tuberculosis infection, and this population serves as an important reservoir for future tuberculosis cases. Prevalence estimates are limited by difficulties in diagnosing the infection, including the lack of an ideal test, and an incomplete understanding of latency. Current tests include the tuberculin skin test and two interferon-γ release assays: QuantiFERON Gold In-Tube and T-SPOT.TB. This update focuses on recent publications regarding the ability of these tests to predict tuberculosis disease, their reproducibility over serial tests, and discordance between tests. We also discuss recent advances in the treatment of latent M. tuberculosis infection, including the three-month regimen of once-weekly rifapentine plus isoniazid, and prolonged isoniazid therapy for HIV-infected persons living in high-tuberculosis-incidence settings. We provide an update on the tolerability of the three-month regimen.