1.3 Drug-resistant TB

Since 1994, the World Health Organization (WHO) has systematically collected and analysed data on levels of resistance to anti-TB drugs from countries and areas (1). Most attention has been given to the proportion of people diagnosed with TB who have rifampicin-resistant TB (RR-TB) and multidrug-resistant TB (MDR-TB, defined as resistance to both rifampicin and isoniazid), collectively referred to as MDR/RR-TB (for data sources and availability, see Box 1.3.1). Since 2022, new methods have been used to produce time series of estimates of the number of people developing MDR/RR-TB each year (incident cases), covering the period from 2015 up to the most recent complete calendar year (2, 3). Data on resistance to other anti-TB drugs are collected as well, but the country coverage of such data is much more limited.

Globally, the estimated annual number of people who developed MDR/RR-TB has been falling since 2015 (Fig. 1.3.1). The estimated number in 2024 was 390 000 (95% uncertainty interval [UI]: 360 000–430 000).

Fig. 1.3.1 Global trend in the estimated number of people who developed MDR/RR-TB (incident cases), 2015–2024

Globally, MDR/RR-TB caused an estimated 150 000 (95% UI: 93 000–210 000) deaths in 2024.

The reason why the number of people developing MDR/RR-TB is not estimated to have increased from 2020–2023, in contrast to the number of people developing TB overall (Section 1.1), is that increases in the overall number of people developing TB have been offset by an estimated downward trend since 2015 in the proportion of people with TB who have MDR/RR-TB (Fig. 1.3.2). In 2024, the combination of a decrease in the number of people developing TB and a decrease in the proportion of people with TB who had MDR/RR-TB led to a more pronounced decrease in the number of people developing MDR/RR-TB, compared with the previous 3 years.

Globally, the estimated proportion of new TB cases with MDR/RR-TB has fallen from 4.7% (95% UI: 3.5–6.0%) in 2015 to 3.2% (95% UI: 2.5–3.9%) in 2024; the estimated proportion of previously treated cases with MDR/RR-TB has fallen from 19% (95% UI: 10–28%) in 2015 to 16% (95% UI: 8.3–23%) in 2024.

Fig. 1.3.2 Global trend in the estimated percentage of people with TB who had MDR/RR-TB, 2015–2024

Trends at regional level vary (Fig. 1.3.3). Between 2020 and 2024, there were estimated increases in the number of people who developed MDR/RR-TB in the WHO Region of the Americas and the WHO South-East Asia Region. In contrast, the estimated number of people developing MDR/RR-TB each year has been declining since 2015 in both the African and Eastern Mediterranean regions. Numbers are also estimated to have been falling for most of the period 2015–2024 in the European Region; a decline in 2023–2024 follows a small blip in 2021 and a flat trend in 2022–2023. After a persistent decline from 2015–2020 and a stable trend from 2021–2023, a decline resumed in 2024 in the Western Pacific Region.

Fig. 1.3.3 Regional trends in the estimated number of people who developed MDR/RR-TB (incident cases), 2015–2024

Trends in the 30 high MDR/RR-TB burden countries also vary (Fig. 1.3.4).

Fig. 1.3.4 Country-specific trends in the estimated number of people who developed MDR/RR-TB (incident cases), 30 high MDR/RR-TB burden countries, 2015–2024^a

Four countries accounted for over half of the global number of people estimated to have developed MDR/RR-TB (incident cases) in 2024: India (32% of global cases), China (7.1%), the Philippines (7.1%) and the Russian Federation (6.7%) (Fig. 1.3.5).

Fig. 1.3.5 Estimated number of people who developed MDR/RR-TB (incident cases) in 2024, for countries with at least 1000 incident cases

The proportion of people with TB who had MDR/RR-TB varies considerably among regions and countries (Fig. 1.3.6, Fig. 1.3.7). For people with no previous history of TB treatment (new cases), best estimates were 2.0% in the WHO African and Eastern Mediterranean regions, 3.1% in the Western Pacific Region, 3.5% in the Region of the Americas and 3.6% in the South-East Asia Region. In contrast, this proportion was 23% in the European Region. For people previously treated for TB, best estimates range from 5.6% in the Eastern Mediterranean Region to 51% in the European Region. At country level, the highest proportions are found in the Russian Federation and in several countries in eastern Europe and Central Asia.

Fig. 1.3.6 Percentage of people with TB who had MDR/RR-TB, for those with no previous history of TB treatment, 2024

Fig. 1.3.7 Percentage of people with TB who had MDR/RR-TB, for those previously treated for TB, 2024

Other patterns of drug resistance

There were an estimated 1.5 million incident cases (95% UI: 0.59–2.4 million) of isoniazid-resistant TB in 2024, including people with both rifampicin-susceptible and rifampicin-resistant TB.

Globally in 2024, the estimated proportion of MDR/RR-TB cases with pre-XDR-TB (i.e. resistance to any fluoroquinolone for which testing was done) was 18% (95% UI: 15–20%).