Immunodiagnosis of tuberculosis: state of the art

ABSTRACT

Undiagnosed and mismanaged tuberculosis [TB] continues to fuel the global TB epidemic. Rapid, accurate and early diagnosis of TB is therefore a priority to improve TB case detection and interrupt transmission. Although considerable improvements have been made in TB diagnostics, there are two major gaps in the existing diagnostics pipeline [1] lack of a simple accurate point-of-care test that can be used for rapid diagnosis at the primary care level; [2] lack of a biomarker [or combination of biomarkers] that can be used to identify latently infected individuals who will benefit most from preventive therapy. Currently available commercial serological [antibody detection] tests are inaccurate and do not improve patient outcomes. Despite this evidence, dozens of serological tests are sold and used in countries [e.g. India] with weak regulatory systems, especially in the private sector. Recognizing the threat posed by these suboptimal tests, a World Health Organization [WHO] Expert Group has strongly recommended against the use of serological tests for the diagnosis of pulmonary and extra-pulmonary TB. Another WHO Expert Group has discouraged the use of interferon-gamma release assays for active pulmonary TB diagnosis in low-and middle-income countries. All existing tests for latent TB infection appear to have only modest predictive value and further research is needed to identify highly predictive biomarkers