2.1 TB incidence

Box 2.1.1 summarizes the methods used to produce estimates of TB incidence between 2000 and 2019, and the new methods that were needed to produce estimates for 2020 and 2021. Estimation of TB incidence during the COVID-19 pandemic is much more difficult than previously. The new methods have been extensively reviewed but rely heavily on country and region-specific dynamic models for low and middle-income countries, in the absence of reliable direct measurements of disease burden from national disease surveillance systems or population-based surveys.

An estimated global total of 10.6 million people (95% uncertainty interval [UI]: 9.9–11 million) fell ill with TB in 2021, equivalent to 134 cases (95% UI: 125–143) per 100 000 population (Table 2.1.1). Among all TB cases, 6.7% were among people living with HIV. Geographically, most TB cases in 2021 were in the WHO regions of South-East Asia (45%), Africa (23%) and the Western Pacific (18%), with smaller shares in the Eastern Mediterranean (8.1%), the Americas (2.9%) and Europe (2.2%).

Table 2.1.1 Global and regional estimates of TB incidence, numbers (in thousands) and rates (per 100 000 population) in 2021

The estimated 10.6 million people (95% UI: 9.9–11 million) who fell ill with TB worldwide in 2021 is an increase of 4.5% from 10.1 million (95% UI: 9.5–10.7 million in 2020), reversing many years of slow decline (Fig. 2.1.1, left panel). Similarly, the TB incidence rate (new cases per 100 000 population per year) is estimated to have increased by 3.6% between 2020 and 2021, following declines of about 2% per year for most of the past two decades (Fig. 2.1.1, right panel).

Fig. 2.1.1 Global trends in the estimated number of incident TB cases (left) and the incidence rate (right), 2000–2021

These reversals of progress are consistent with projections published in the Global tuberculosis report 2021 (1). They reflect the estimated impact of disruptions to essential TB services during the COVID-19 pandemic: in particular, drops in the number of people newly diagnosed and officially reported with TB in many countries in 2020 and 2021 (Section 1), under the assumption that these reflect true drops in case detection (as opposed to an increase in underreporting). Increases in the number of people with TB who are not detected by health services results in increases in the number of people with undiagnosed and untreated TB in the community. This increases transmission of TB infection, which in turn, with a time-lag, increases the number of people who go on to develop TB disease. These impacts may be partially offset by the effect of COVID-related restrictions on transmission; the dynamic models used to estimate TB incidence assume a 50% reduction in transmission during severe restrictions (lockdowns).

Globally, the number of people newly diagnosed and officially reported with TB fell from 7.1 million in 2019 to 5.8 million in 2020 (-18%), with a partial recovery to 6.4 million in 2021 (Section 1). The impact of these shortfalls on TB transmission was relatively limited in 2020, given the time lag between acquisition of infection and breakdown to TB disease (which varies from months to many years), but more pronounced in 2021 given the extra year for the consequences of disruptions in 2020 to be manifested and the additional impact of disruptions in 2021.

Increases in the number of people not detected and thus not treated for TB also result in increases in the number of deaths caused by TB (Section 2.2). The impact of reduced case detection on TB mortality is severe and more immediately noticeable, since there are more people with untreated TB.

The cumulative fall in the TB incidence rate was 13.5% between 2015 and 2020, but the level of 2021 was only 10% below that of 2015. This was only half-way to the first End TB Strategy milestone of a 20% reduction between 2015 and 2020 (right panel of Fig. 2.1.1) and a long way from the second milestone of a 50% reduction by 2025 (2, 3).

In 2021, eight countries accounted for more than two thirds of global TB cases: India (28%), Indonesia (9.2%), China (7.4%), the Philippines (7.0%), Pakistan (5.8%), Nigeria (4.4%), Bangladesh (3.6%) and Democratic Republic of the Congo (2.9%) (Fig. 2.1.2).

Fig. 2.1.2 Estimated TB incidence in 2021, for countries with at least 100 000 incident cases

The severity of national TB epidemics, in terms of the number of incident TB cases per 100 000 population per year, varies widely among countries (Fig. 2.1.3). In 2021, countries with the highest rates were mostly in the WHO African Region.

Fig. 2.1.3 Estimated TB incidence rates, 2021

The proportion of people with a new episode of TB (either new or relapse cases) who were coinfected with HIV was also highest in countries in the WHO African Region, exceeding 50% in parts of southern Africa (Fig. 2.1.4).

Fig. 2.1.4 Estimated HIV prevalence in people with new or relapse TB, 2021

TB affects people of both sexes and all age groups (Fig. 2.1.5), with the highest burden in adult men (57% of all TB cases in 2021). By comparison, adult women accounted for 33% and children for 11%.

Fig. 2.1.5 Global estimates of TB incidence numbers and case notifications disaggregated by age and sex (female in purple; male in green), 2021

Regional estimates of the distribution of TB cases by age and sex are shown in Fig. 2.1.6.

Fig. 2.1.6 Regional estimates of TB incidence numbers and case notifications disaggregated by age and sex (female in purple; male in green), 2021

At regional level, trends in the TB incidence rate vary and progress in relation to the 2020 milestone of the End TB Strategy (a 20% reduction compared with a baseline of 2015) is mixed (Fig. 2.1.7). The TB incidence rate increased between 2020 and 2021 in five of the six WHO regions, reflecting the estimated impact of shortfalls in TB case detection in 2020 and incomplete recovery in 2021. The exception was the African Region, where COVID-related disruptions have had little impact on the number of people diagnosed and officially notified with TB. In 2021, the African Region passed the 2020 milestone of the End TB Strategy, with a 22% reduction compared with 2015. Despite an upturn between 2020 and 2021, the TB incidence rate in 2021 in the European region was still 25% lower than in 2015. For other regions, the milestone is still some way off.

Fig. 2.1.7 Trends in estimated TB incidence rates by WHO region, 2000–2021

Trends in the TB incidence rate in the 30 high TB burden countries are mixed. Between 2020 and 2021, there were estimated increases in countries with major shortfalls in TB notifications in 2020 and 2021 (e.g. India, Indonesia, Myanmar, Philippines), while in others the previous decline in the TB incidence rate has slowed or stabilized. In 2021, the best estimate of the TB incidence rate suggested that the 2020 milestone of the End TB Strategy had been reached in 7 countries: Ethiopia, Kenya, Lesotho, Namibia, South Africa, the United Republic of Tanzania and Zambia (Fig. 2.1.8).

Fig. 2.1.8 Trends in estimated TB incidence rates in the 30 high TB burden countries ^a compared with notifications of new and relapse cases, 2000–2021

All of the three global TB watchlist countries have reached the 2020 milestone (Fig. 2.1.9).

Fig. 2.1.9 Trends in estimated TB incidence rates in the 3 global TB watchlist countries compared with notifications of new and relapse cases, 2000–2021

In total, 77 countries had reached the 2020 milestone by 2021 (Fig. 2.1.10).

Fig. 2.1.10 Countries which, by 2021, had reached the 2020 milestone of the End TB Strategy for reducing the TB incidence rate

Notes: Table 2.1.1 was updated on 23 January 2023 (previously the rate per 100 000 population columns for the South-East Asia Region were showing data for the Eastern Mediterranean Region, and vice versa). Figures 2.1.11 and 2.1.12 were updated on 26 January 2023 to show the correct categories for some countries .

For more information

Country-specific details are available in the Global tuberculosis report app and country profiles.

References