About 2 billion people are infected with tuberculosis worldwide. Although preventable and treatable, this disease continues to claim over 4,000 lives every day. Last year alone, the World Health Organization (WHO) reported that 1.6 million people died of TB. The COVID-19 pandemic derailed the decreasing trend in the number of new cases observed in 2018-2019 with the figures already returning to the 2017 level in 2020. To raise awareness of the significant impact of the global TB epidemic and the urgency to beat it, World TB Day is observed annually on March 24th.
TB is a communicable disease that remains one of the leading causes of death globally. Prior to the emergence of the COVID-19 pandemic, TB was the primary cause of death from a single infectious agent, outranking HIV/AIDS. The disease is caused by mycobacterium tuberculosis which spreads when infected individuals expel bacteria into the air, such as by coughing. Approximately a quarter of the world’s population is estimated to have been infected with TB, but most individuals will not go on to develop the disease, and some may even recover from the infection themselves. However, of those who do develop TB, around 90% are adults, with a higher incidence among men than women.
Without treatment, the mortality rate from TB is alarmingly high, with roughly 50% of those infected dying as a result of the disease. Fortunately, by taking the recommended course of anti-TB drugs over a 4-6-month period, about 85% of infected individuals can be cured. However, despite being a preventable and curable illness, TB remains a significant public health concern in many parts of the world.
Between 2005 and 2019, there was a global decline in the number of annual TB-related deaths, but this trend was reversed in 2020 and 2021. In 2021, it was estimated that 1.4 million HIV-negative individuals and 187,000 HIV-positive individuals died from TB, resulting in a combined total of 1.6 million deaths. This figure is higher than the estimated 1.5 million deaths in 2020 and 1.4 million deaths in 2019 and has returned to the same level as in 2017. The progress achieved towards the first milestone of the End TB Strategy, which aimed to reduce TB-related deaths by 35% between 2015 and 2020, has been reversed. As of 2021, the net reduction in deaths since 2015 is only 5.9%.
Fig.1. The estimated number of TB deaths and mortality rates from 2000 to 2021
Number
Rate per 100 000 population
Source: WHO
According to WHO’s published estimates of global deaths by cause, in 2019 TB was the foremost cause of death from a single infectious agent globally (2019 is the most recent year for which data is available). It is expected that in 2020 and 2021, TB will be ranked second as a cause of death from a single infectious agent, with COVID-19 taking the top spot.
Worst-hit regions, categories
In 2021, the WHO African and South-East Asia regions accounted for 82% of total TB deaths among HIV-negative individuals, with India alone contributing to 36% of the cases. Similarly, these regions also accounted for 82% of the combined total of TB deaths among both HIV-negative and HIV-positive individuals, with India accounting for 32% of the cases.
Fig.2. Global and regional estimates of TB mortality, numbers (in thousands) and rates (per 100 000 population) in 2021 (Low and high are the 5th and 95th percentiles of the uncertainty interval (UI))
Source: WHO
In terms of gender, globally in 2021, more men (54%) than women (32%) or children (14%) (aged <15 years) who were HIV-negative died from TB. The proportion of TB deaths among children is higher than their estimated percentage of cases (11%), indicating that they have limited access to diagnosis and treatment. Among those who were HIV-positive, 51% were men, 38% were women, and 11% were children.
Fig.3. Global distribution of estimated TB mortality in HIV-negative individuals by age group and gender, 2021 (male in green and female in purple)
Source: WHO
Prevention, treatment budget
The World Health Organization estimates that an annual budget of US$13 billion is required to meet global targets for TB prevention, diagnosis, treatment, and care as agreed upon at the high-level UN TB meeting. However, unfortunately, global spending on essential TB services decreased from US$6.0 billion in 2019 to US$5.4 billion in 2021. International donor funding, mainly from the Global Fund to Fight AIDS, Tuberculosis and Malaria, remains critical in low- and middle-income countries, with the United States being the largest donor, contributing almost 50% of international donor funding for TB.
Mycobacterium tuberculosis was discovered on March 24, 1882, by Dr. Robert Koch. Back then, the disease claimed the lives of one in every seven people in the United States and Europe. A century later, in 1982, March 24 was officially designated as World TB Day, being observed annually. The theme of this year’s World TB Day is “Yes! We can end TB!” and is aimed at encouraging high-level leadership, accelerated action, and cooperation to combat the TB epidemic.