IGRA Variability and the Effect of TST

Seven days after TST placement, IGRA responses were boosted beyond the defined baseline variability; such boosting persisted for up to 3 months.

The tuberculin skin test (TST) and interferon-γ release assays (IGRAs) are important tools for identifying individuals with latent TB infection (LTBI). Although CDC guidelines recommend use of IGRAs alone to detect persons with LTBI, guidelines in Canada and the U.K. suggest a two-step strategy: a TST followed by an IGRA. However, neither the within-patient variability of IGRAs nor the effect of a recent TST on IGRA results has been carefully studied.

To explore these issues, researchers conducted a study involving 26 healthy healthcare workers in Capetown, South Africa. IGRAs were performed once each week for 4 weeks before TST placement, to measure within-patient variability. They were also performed 3, 7, 28, and 84 days after TST placeme…

Reviewing Author

Neil M. Ampel, MD

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Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Neil M. Ampel, MD

Disclosures

Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

IGRA Variability and the Effect of TST

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Reviewing Author