16.1 Introduction

Exposure to M. tuberculosis may result in latent tuberculosis infection (LTBI). WHO defines LTBI as a state of persistent immune response to stimulation by M. tuberculosis antigens with no evidence of clinically manifest active tuberculosis (TB)1. This is also referred to as “tuberculosis infection”.

Identification and treatment of LTBI can reduce TB morbidity and mortality, as well as TB transmission.

 Tuberculin skin test (TST) or interferon-gamma release assay (IGRA) can be used to detect LTBI (Chapter 3).

The goal of LTBI treatment is to reduce the risk of progression to active TB. It must be initiated only once active TB has been ruled out by appropriate evaluation.

If a patient develops signs and symptoms of active TB while on LTBI treatment, a specimen should be taken for diagnosis and detection of drug resistance (Xpert MTB/RIF, Xpert MTB/XDR, culture and drug susceptibility test, DST) and according to the results, TB treatment should be initiated.



  1. WHO consolidated guidelines on tuberculosis: module 1: prevention: tuberculosis preventive treatment. Geneva: World Health Organization; 2020.