Management of Latent Tuberculosis Infection in Children from Developing Countries

Tuberculosis (TB), once widely prevalent throughout the world, experienced falling incidence rates in early twentieth century in developed nations, even before the introduction of anti-TB drugs, attributed to improved hygiene and living conditions. Active TB may develop following fresh infection or activation of latent tuberculosis infection (LTBI). LTBI is a state of persistent bacterial viability, however, the host stays asymptomatic and there is no evidence of clinically active tuberculosis. Therefore, treatment of all LTBI is considered as one of the ways to control tuberculosis. Diagnosis of LTBI relies on presence of immune-reactivity to TB antigen and commonly used tests include tuberculin skin test and interferon gamma release assay (IGRA). At present there is no diagnostic test that can identify an individual with LTBI who will progress to develop active disease or remain asymptomatic. Therefore, it is unclear whom to treat. In the current scenario, treatment for LTBI is restricted to high risk groups which include under-5 y contacts of adults with pulmonary TB. Various regimens for treatment of LTBI are evolving and consist of isoniazid (INH) alone for 6-9 mo or combination of INH and rifampicin for 3-4 mo or once a week combination of rifapentin and INH for 3 mo. There is a need for research to identify LTBI, risk factors for progression of LTBI to active disease and a shorter regimen for treatment.