1.7 Global burden of tuberculosis

1.7.1 Latent tuberculosis infection

The global prevalence of LTBI is unknown due to difficulties in diagnosis. However, WHO estimates that one-quarter of the world population has LTBI [1] Citation 1. Houben RM, Dodd PJ. The Global Burden of Latent Tuberculosis Infection: A Re-estimation Using Mathematical Modelling. PLoS Med. 2016;13(10):e1002152. Published 2016 Oct 25.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5079585/pdf/pmed.1002152.pdf .

1.7.2 Active tuberculosis

Globally, active TB remains a leading cause of death from infectious disease.

WHO estimates that each year there are approximately 10 million incident cases of TB and 1.5 million deaths due to TB, including 1.3 million among HIV-negative individuals and 214,000 among HIV-infected individuals [2] Citation 2. World Health Organization. Global Tuberculosis Report 2021. Geneva: World Health Organization; 2021.
https://apps.who.int/iris/rest/bitstreams/1379788/retrieve .
Children under 15 years account for 11% of all estimated TB cases [2] Citation 2. World Health Organization. Global Tuberculosis Report 2021. Geneva: World Health Organization; 2021.
https://apps.who.int/iris/rest/bitstreams/1379788/retrieve . However, TB cases in children are frequently undiagnosed and unreported.

While the absolute number of global TB cases is stable, there are large individual country and regional differences in incidence and prevalence.

Most TB cases are in Southeast Asia (43%), Africa (25%) and the Western Pacific (18%), with lower percentages in the Eastern Mediterranean, the Americas and Europe [2] Citation 2. World Health Organization. Global Tuberculosis Report 2021. Geneva: World Health Organization; 2021.
https://apps.who.int/iris/rest/bitstreams/1379788/retrieve .

1.7.3 Drug-resistant tuberculosis 

Drug-resistant TB (DR-TB) is a growing worldwide problem, and no region is spared.

WHO estimates that annually worldwide there are [3] Citation 3. World Health Organization. Global Tuberculosis Report 2020. Geneva: World Health Organization; 2020.
https://apps.who.int/iris/rest/bitstreams/1312164/retrieve :
• More than one million rifampicin-susceptible and isoniazid-resistant TB (Hr-TB) cases (11% of all incident TB cases).
• 3.3% of new cases and 18% of previously treated cases, with multidrug-resistant TB (MDR-TB) a Citation a. Multidrug-resistant: resistance to at least rifampicin and isoniazid. and rifampicin-resistant TB (RR-TB) b Citation b. Rifampicin-resistant: resistance to rifampicin, with or without resistance to other TB drugs. representing 465,000 cases and 182,000 deaths.

In Eastern Europe and Central Asia, TB incidence is lower than in Southeast Asia and Africa, but up to 30% of new and 65% of retreatment cases exhibit rifampicin-resistance.

In China and India, there is a low proportion of rifampicin-resistant cases among all TB cases. However, because of their large populations, these two countries represent 41% of global MDR/RR-TB cases.

Resources for detecting drug resistance are limited in many parts of Africa. However, available data suggest that the MDR-TB burden is significant, especially in the south.

The prevalence of extensively drug-resistant TB (XDR-TB) c Citation c. Extensively drug-resistant: rifampicin-resistance with resistance to any fluoroquinolone, and at least either bedaquiline or linezolid. , according to the new WHO definition, is currently unknown.