Ending tuberculosis strategy: Course correction needed

Prof Guy Marks, President of the International Union Against Tuberculosis and Lung Disease, argues that we need a course correction on the strategy for ending tuberculosis, including in Asia

Since the discovery of Mycobacterium tuberculosis over 140 years ago, scientists have developed tests and medicines to diagnose and treat tuberculosis (TB) effectively. Using these tools, the disease has been virtually eliminated in many ‘Western’ countries, where today, it is barely considered a threat.

This complacency is a mistake. TB remains a threat to everyone in the world, killing more people than any other infectious disease. This burden is particularly felt in Asia; of the top-eight countries (1) for TB incidence outlined by the WHO, accounting for two-thirds of all cases worldwide, six are in Asia. The Southeast Asia region alone accounted for 46% of all cases (1) in 2022.

The fact that so many suffer so much illness and death due to a disease that has been largely eliminated decades ago in other countries is both a massive injustice, and one of the greatest failures in global health action. In 2024, we have modern diagnostics and tablet-based treatment regimens that allow us to diagnose and successfully treat virtually everyone with TB. We are running out of excuses not to end TB everywhere. Applying the learnings in community-wide active case finding, which have brought success in Europe, North America and Oceania, to high-burden countries in Southeast Asia must be the first step in righting this wrong.

If it is possible to end TB anywhere, it must be possible to end it everywhere – this must be our goal.

Ending tuberculosis by breaking the chain of transmission

There is much that is good about current efforts to end TB globally. Action to address the socio-economic, behavioural and health determinants (especially, undernutrition, crowded living conditions, smoking, HIV and diabetes), as well as access to better tests and treatments for TB, are extremely important.

Southeast Asia is at the forefront of this; it’s one of the reasons we will be hosting the upcoming Union World Conference on Lung Health in Bali this November. And initiatives such as Indonesia’s leadership of the Global Alliance to Combat TB exemplify the energy there is to eradicate this disease. (2)

But progress remains slow. The fundamental reason for this is the infectious nature of the disease. Like COVID, influenza and measles, TB is spread from person-to-person by airborne droplets.

And unfortunately, many people with infectious TB (probably more than 50%) do not experience the symptoms that might drive them to seek medical attention. (3) These people remain infectious to others until either they seek care and receive treatment for TB or they recover spontaneously – often over many months.

It is this ongoing transmission of TB within households and communities, mainly from people with infectious TB but without symptoms, a diagnosis or treatment, that is
sustaining the TB epidemic.

Ending tuberculosis in Southeast Asia and beyond

Ending TB will mean finding and treating as many people as possible with infectious forms of TB so that they do not infect others.

In high-burden settings such as India, Indonesia, and the Philippines, this means screening everyone until the number of people with infectious TB in the community is low enough to end sustained (endemic) transmission. This way, we can break the chain of transmission and end this disease for good.

Indeed, this approach was taken in many countries in the third quarter of the 20th century. Despite the success of mass chest X-ray screening in ending TB as a public health threat in many of these countries, mass screening was phased out in the 1970s and 1980s, but why?

Fifty years ago, the WHO Expert Committee on Tuberculosis released its 9th Report (4), which advised that “indiscriminate” (read: ‘universal’) screening be abandoned, even though many countries in the world – particularly across Southeast Asia – still had very high TB burdens with high rates of community transmission of the infection. In the 50 years since this Report was released, those countries have continued to suffer from an unacceptably high burden of TB.

Unfortunately, the unwillingness to implement universal screening in high-burden locations has also persisted.

A worthwhile investment to ending tuberculosis

A universal screening programme for TB in any country would be a large undertaking requiring substantial upfront investment. However, this would generate an excellent return.

We know that this approach works. My colleagues and I implemented community-wide active case finding for tuberculosis in a southern, rural province of Vietnam. (5) We found a 57% decrease in TB incidence (newly detected people with TB) over three years – a dramatic acceleration towards ending TB. (6) The global average decline in the incidence of TB is 2% per year. (7)

Time for ambition: Ending tuberculosis for good

In my view, there is no other disease where the failure to translate the benefits of scientific innovation and knowledge into public health gains is starker. It is unjust that so many countries in Southeast Asia continue to suffer the ravages of TB when other countries across Europe, North America and Oceania rid themselves of this disease decades ago.

The time is right for ambition. We must be brave and accept that we need a course correction to finish the job of ending TB for good – and the governments of high-burden countries in Southeast Asia have the potential to lead here.

The time is right for ambition. We must be brave and accept that we need a course correction to finish the job of ending TB for good – and the governments of high-burden countries in Southeast Asia have the potential to lead here.

References

1. World Health Organization (2023). Global Tuberculosis Report 2023; 1.1.
   TB Incidence. Available at: https://www.who.int/teams/global-tuberculosis-programme/tb-reports/global-tuberculosis-report-2023/tb-disease-burden/1-1-tb-incidence#:~:text=The%20eight%20countries%20ranked%20in,Democratic%20Republic%20of%20the%20Congo
2. Ministry of Foreign Affairs of the Republic of Indonesia (2024). Indonesia
   Leads Establishment of Global Alliance at UN to Combat Tuberculosis.
   Available at: https://kemlu.go.id/portal/en/read/5733/berita/indonesia-leadsestablishment-of-global-alliance-at-un-to-combat-tuberculosis. Accessed
   September 2024.
3. Kendall EA, Shrestha S, Dowdy DW. The Epidemiological Importance of
   Subclinical Tuberculosis. A Critical Reappraisal. Am J Respir Crit Care Med.
   2021 Jan 15;203(2):168-174. doi: https://doi.org/10.1164/rccm.202006-2394PP. PMID:
   33197210; PMCID: PMC7874405.
4. WHO Expert Committee on Tuberculosis & World Health Organization. (1974).
   WHO Expert Committee on Tuberculosis [meeting held in Geneva from 11 to
   20 December 1973]: ninth report. World Health Organization.
   https://iris.who.int/handle/10665/41095
5. Marks GB, Nguyen NV, Nguyen PTB, Nguyen TA, Nguyen HB, Tran KH, Nguyen
   SV, Luu KB, Tran DTT, Vo QTN, Le OTT, Nguyen YH, Do VQ, Mason PH, Nguyen
   VT, Ho J, Sintchenko V, Nguyen LN, Britton WJ, Fox GJ. Community-wide
   Screening for Tuberculosis in a High-Prevalence Setting. N Engl J Med. 2019
   Oct 3;381(14):1347-1357. doi: https://doi.org/10.1093/10.1056/NEJMoa1902129. PMID: 31577876.
6. Marks GB, Ho J, Nguyen PTB, Nguyen TA, Boi KL, Tran KH, Nguyen SV,
   Nguyen NV, Nguyen HB, Nguyen LN, Garden FL, Fox GJ. A Direct Measure of
   Tuberculosis Incidence – Effect of Community Screening. N Engl J Med. 2022
   Apr 7;386(14):1380-1382. doi: https://doi.org/10.1093/10.1056/NEJMc2114176. PMID: 35388676.
7. World Health Organization (2022). Global Tuberculosis Report 2022. 2.1 TB
   Incidence. Available at: https://www.who.int/teams/global-tuberculosis-programme/tb-reports/global-tuberculosis-report-2022/tb-disease-burden/2-1-tb-incidence. Accessed September 2024.