Only tuberculin skin tests (TST) and two interferon-γ release assays (IGRA) - QuantiFERON-TB Gold In-Tube and T-SPOT.TB - are currently endorsed by the World Health Organization as tests for tuberculosis (TB) infection. While IGRAs are more specific than TST, they require sophisticated laboratory infrastructure and are costly to perform. However, both types of tests have limited performance to predict development of active TB. Tests with improved predictive performance and operational characteristics are needed.We reviewed the current landscape of tests for TB infection identified through a web-based survey targeting diagnostic manufacturers globally.We identified 20 tests for TB infection including 15 in-vitro tests and five skin tests. Thirteen of the in-vitro tests are whole-blood IGRA and 14 uses early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10), with or without additional antigens. Ten are based on assays other than an enzyme-linked immunosorbent assay such as a fluorescent lateral flow assay, which requires less manual operation and shorter assay time and hence is more suitable for decentralisation compared to the existing IGRA.Four of the five skin tests use ESAT-6 and CFP-10 proteins while the remaining one uses a new antigen that is specific to Mycobacterium tuberculosis complex.New tests have the potential to improve accuracy, operational characteristics and end-user access to tests for TB infection. However, published data in various populations and settings are limited for most new tests. Evaluation of these new tests in a standardised design would facilitate their endorsement and programmatic scale-up.
Yohhei Hamada, Daniela Maria Cirillo, Alberto Matteelli, Adam Penn-Nicholson, Molebogeng X Rangaka, Morten Ruhwald