News24 | TB is again the world's deadliest infectious disease, says WHO

• An estimated 56 000 people in SA and 1.25 million around the world died of TB in 2024.
• It means that, in 2023, TB overtook Covid-19 as the top infectious disease killer on the planet.
• Spotlight unpacks the new numbers, and how it compares to domestic sources of TB figures.

An estimated 56 000 people died of tuberculosis (TB) in South Africa in 2023, according to figures published on Tuesday by the World Health Organisation (WHO).

Around 31 000 of the deaths were people living with HIV, and 25 000 not living with HIV. 

Together with the latest edition of its World TB Report, the WHO also published several country profiles.

South Africa's can be viewed here.

The WHO estimates that around 270 000 people fell ill with TB in South Africa in 2023, with around 13 000 falling ill with drug-resistant forms of TB.

As shown in the above graph, the WHO's figures suggests that the number of people falling ill with TB in South Africa are steadily declining. Only a relatively small fraction of people with TB infection fall ill with the disease. 

The latest numbers suggest that South Africa is on track to meet the WHO's target to reduce TB incidence by 50% from 2015 to 2025. According to the WHO, it had reduced by 57% by 2023.

We are, however, not on track to meet the WHO's target to reduce TB deaths by 75% over the same time span. By 2023, the WHO estimates it has only come down by 16%.

These two targets are from the WHO's End TB Strategy.

As shown in the above graph, the decline in TB deaths over the last decade or so was mostly driven by the decline in people living with HIV who have died of TB.

By comparison, TB deaths in people who do not have HIV have been relatively stable. 

How the figures compare 

Another important source of TB numbers in South Africa is Thembisa – a mathematical model developed at the University of Cape Town that is best known for its HIV estimates. It was recently expanded to also produce TB estimates.  

According to Thembisa, around 326 000 adults (defined as people aged 15 and older) fell ill with TB in 2022 (technically mid-2022 to mid-2023). This is significantly higher than the WHO's figure of 270 000 people in 2023, which also includes people younger than 15.

While these specific estimates seem somewhat at odds, the WHO's estimates do come with very wide confidence intervals, which suggests that some of these numbers should, at most, be seen as ball-park figures.  

Though a widely reported figure tends to be the number of people who fall ill with TB in a particular year (incidence), the total number of people ill with TB (prevalence) can be much higher since there will be people who are still ill from previous years. Thus, while the Thembisa estimate is that 326 000 adults fell ill with TB in 2022, an estimated total of 516 000 adults were actually ill with TB in that year.  

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The Thembisa estimate for TB deaths in adults in South Africa in 2022 is just over 60 000, around 4 000 higher than the WHO estimate (which is for both adults and children). 

The WHO and Thembisa estimates for TB deaths are both much higher than the figures reported by Stats SA in their mortality reports. This is to be expected, given that Stats SA provides a count of reported causes of death (which results in an undercount since TB is often not indicated on death certificates), while the WHO and Thembisa use mathematical modelling to estimate the true toll.

According to the most recent Stats SA mortality figures, just under 20 000 TB deaths were recorded in South Africa in 2020 - the Covid-19 pandemic may have contributed to a particularly large undercount in that year. 

The global picture 

According to a WHO media statement, their new report highlights "mixed progress in the global fight against TB". On the positive side, global TB deaths have decreased from an estimated 1.32 million in 2022 to 1.25 million in 2023.

On the negative side, the number of people who fell ill with TB increased slightly year-on-year to an estimated 10.8 million in 2023. Of these, 8.2 million people were diagnosed – around 2.7 million people who fell ill with TB were not diagnosed (these are figures as shared in the WHO media statement.

We are aware that 8.2 million + 2.7 million adds up to 10.9 million and not 10.8 million – this discrepancy is likely a result of some rounding of numbers in the WHO statement. 

A massive 26% of the world's TB burden is in India, followed by Indonesia with 10%, China and the Philippines with 6.8% each, and Pakistan with 6.3%. Together, these five countries account for well over half of the world's TB burden. 

Compared to these five countries and the global total of 10.8 million, the 270 000 new TB cases in South Africa is low in absolute terms. But when taking into account the size of the South African population, our numbers are some of the highest. South Africa had an estimated 427 new TB cases per 100 000 people in 2023. 

The WHO maintains lists of 30 high burden countries for TB, HIV-associated TB, and drug-resistant TB. South Africa is on all three. 

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According to the WHO, in 2023, TB was again the top infectious disease killer on the planet – Covid-19 was top of the list from 2020 to 2022. 

"The fact that TB still kills and sickens so many people is an outrage, when we have the tools to prevent it, detect it and treat it," Dr Tedros Adhanom Ghebreyesus, the WHO's director-general, is quoted as saying in a statement.

"WHO urges all countries to make good on the concrete commitments they have made to expand the use of those tools, and to end TB." 

*This article was first published by Spotlight – health journalism in the public interest. Sign up to the Spotlight newsletter.