Consolidated Guidelines

Testing for TBI increases the certainty that individuals targeted for TPT will benefit better from it. There is, however, no gold standard test for diagnosing TBI. All the currently available tests – TST, IGRA and TBST – are indirect and require a competent immune response for a valid result. A positive test result by any one method is not by itself a reliable indicator of the risk of progression to TB disease. The evidence and the recommendations for TBI testing are discussed in this section.

1. Getahun H, Matteelli A, Chaisson RE, Raviglione M. Latent Mycobacterium tuberculosis infection. N Engl J Med. 2015;372(22):2127–35. doi:10.1056/NEJMra1405427.
2. Dodd PJ, Gardiner E, Coghlan R, Seddon JA. Burden of childhood tuberculosis in 22 high-burden countries: a mathematical modelling study. Lancet Glob Health. 2014;2(8):e453–9. doi:10.1016/S2214-109X(14)70245-1.
3. Houben RMGJ, Dodd PJ. The global burden of latent tuberculosis infection: a re-estimation using mathematical modelling. PLoS Med. 2016;13(10):e1002152.

The review of evidence for the current update exposed additional knowledge gaps to those reported in other recent updates of the guidelines. Continued research on development and on implementation remains critical for many aspects of PMTPT (136). Some information can be collected from user feedback.

Coverage of contact investigation and TPT among child contacts and people with HIV are two of the top 10 core indicators for monitoring implementation of the End TB Strategy (8). National TB and HIV programmes report data yearly to WHO and UNAIDS on progress in PMTPT in target populations (41,130). PMTPT should include monitoring and evaluation systems that are aligned with national TB patient monitoring and surveillance systems. They should include coverage of TPT with levofloxacin among contacts exposed to MDR/RR-TB.

Among individuals infected with M. tuberculosis, it is estimated that the average lifetime risk of progressing to TB disease is about 5–10% (4). The risk is particularly elevated among children under 5 years and among people with compromised immunity (1). As any treatment entails risk of harms and opportunity costs, TPT should be selectively targeted to population groups at highest risk of progression to TB disease, who would benefit most.

Note: The definitions listed below apply to the terms as used in these guidelines. They may have different meanings in other contexts.

Active case finding (ACF): is synonymous with systematic screening for tuberculosis (TB) disease, although usually implemented outside a health facility.

Adolescent: is a person aged 10–19 years.

Adult: is a person aged > 19 years.

WHO guidelines on TPT are premised on the probability that TBI will progress to TB disease in specific risk groups, on the underlying epidemiology and burden of TB and on the feasibility and the public health benefit of the intervention. WHO global policy is expected to provide the basis for the development of national guidelines for PMTPT, adapted to local circumstances. These guidelines envisage a massive extension of TPT, including to individuals exposed to MDR/RR-TB, whereas global coverage of the intervention is still very low, even in priority target groups (10).

Tuberculosis infection (TBI) is defined as a state of persistent immune response to stimulation by M. tuberculosis antigens with no evidence of clinically manifest TB disease (1). As there is no “gold standard” test for TBI, the global burden is not known with certainty; however, about one fourth of the world’s population is estimated to have been infected with M.