New diagnostics for latent and active tuberculosis: state of the art and future prospects

Tuberculosis (TB) continues to be the world's most important infectious cause of morbidity and mortality among adults. Nearly 9 million people develop TB disease each year, and an estimated 1.6 million die from the disease. Despite this enormous global burden, case detection rates are low, posing serious hurdles for TB control. Conventional TB diagnosis continues to rely on antiquated tests such as sputum smear microscopy, culture, tuberculin skin test, and chest radiography. These tests have several limitations and perform poorly in populations affected by the HIV epidemic. Conventional tests for detection of drug resistance are time consuming, tedious, and inaccessible in most settings. In this review, we describe recent advances in the diagnosis of latent and active TB, and detection of drug resistance. Although the perfect test will not be ready for large-scale roll-out and integration into routine TB care services for some time, substantial progress has been made in expanding the TB diagnostic product pipeline. With the resurgence of interest in the development of new tools for TB control, and the recent influx of funding and political support, it is likely that the next few years will see the introduction of new diagnostic tools into routine TB control programs.