Introduction

People with Mycobacterium tuberculosis infection without active disease have latent tuberculosis (TB). Latent TB can be identified by a positive tuberculin skin test (TST) or a TB-specific interferon gamma release assay (IGRA). Interpretation of the tuberculin skin test and interferon gamma release assay is complex and requires a detailed patient history and careful patient assessment—seek expert advice. Individuals with positive tests should be clinically assessed for evidence of active TB. Consider HIV testing in patients with latent TB.

Treatment of latent TB reduces the incidence of progression to active disease. Once active disease has been excluded, consider treatment of latent TB in:

• patients with HIV infection
• recent converters from a negative to positive tuberculin skin test (TST) or TB-specific interferon gamma release assay (IGRA) (within last 2 years)
• close contacts of a patient with smear-positive pulmonary TB
• people younger than 35 years (even if no known TB contact)
• healthcare workers
• patients who are immunocompromised or are receiving (or expected to receive) immunosuppressive drugs—seek expert advice. See also Additional considerations in immunocompromised patients.

In pregnant women, the timing of treatment of latent TB is complex and the risk of progression to active disease needs to be weighed against the increased risk of drug-induced hepatotoxicity in pregnancy. Treatment can often be deferred until the postpartum period unless there is a high risk of progression to active disease—seek expert advice. Risk factors for progression to active disease include recent exposure to TB, HIV coinfection and immunocompromise. A neonate born to a woman with latent TB does not require treatment.