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Testing and treating TB – the challenges

Image: The Global Fund / Vincent Becker

The World Health Organization (WHO) declared tuberculosis (TB) a global emergency 25 years ago, yet TB remains among the top 10 causes of death worldwide and the leading infectious disease killer. TB is preventable and curable, yet millions of people with TB do not have access to affordable diagnostic tests and treatment – especially in developing countries.

The WHO estimates[1] that nearly one-quarter of the global population has latent TB infection (LTBI). Unless they receive the right diagnosis and treatment, around 10% of those carrying latent TB infection will develop the contagious form of the disease – continuing the vicious cycle of putting themselves, and those around them in harm’s way and reseeding the pool of tomorrow’s TB with LTBI.

Global experts agree that the solution to ending the global TB epidemic is two-pronged. We must detect and treat people with active TB, but also reduce the large reservoir of latent TB infection, to end the cycle of the disease.

The world’s deadliest infectious disease

Worldwide, TB is the leading cause of death from a single infectious agent (surpassing even HIV/AIDS). According to the WHO, “a total of 1.5 million people died from TB in 2018 (including 251,000 people with HIV)”.

“In 2018, an estimated 10 million people fell ill with tuberculosis (TB) worldwide. 5.7 million men, 3.2 million women and 1.1 million children. There were cases in all countries and age groups.”

“In 2018, 1.1 million children[2] fell ill with TB globally, and there were 205,000 child deaths due to TB (including among children with HIV). Child and adolescent TB is often overlooked by health providers and can be difficult to diagnose and treat.” Preventative regimes are much better tolerated by children compared to adults, but, sadly, programmes for children over the age of five who are exposed to TB do not exist in high-burden countries and are often poorly implemented for children under age five.

Preventative testing and treatment saves lives

The WHO End TB Strategy, launched in 2015, carried a bold vision statement: “A world free of tuberculosis – zero deaths, disease and suffering due to tuberculosis.” Can this vision ever be reached?

Although some progress has been made, millions continue to lose their lives to TB. Current TB control measures seem unlikely to meet 2020 and 2025 milestones set out in the End TB Strategy[3] (respectively, a 35% and 75% reduction in TB deaths compared with 2015). Globally, TB incidence is falling at about 2% per year. This needs to accelerate to a 4–5% annual decline to reach the 2020 milestones of the End TB Strategy[3].

However, in September 2018, the first ever UN High-level meeting on TB was held and world leaders agreed that only expanded testing and treatment of latent TB infection can end the cycle of disease transmission. As a first major international step, they passed the POLITICAL DECLARATION OF THE HIGH-LEVEL MEETING OF THE UNITED NATIONS GENERAL ASSEMBLY ON THE FIGHT AGAINST TUBERCULOSIS.[4]  Among its key proclamations, it calls for preventive treatment of 30 million persons by 2022, and for international agencies to fund and rapidly scale up the WHO’S End TB Strategy. The Assembly also committed to mobilise sufficient and sustainable financing for universal access to quality prevention, diagnosis, treatment and care of tuberculosis, from all sources, with the aim of increasing overall global investments for ending tuberculosis and reaching at least 13 billion United States dollars a year by 2022.  

Targeted testing and treatment of latent TB

People with active TB can infect five to 15 other people, through close contact, over the course of a year. Treatment of LTBI eliminates the bacteria before infection become contagious, preventing spread of the disease. Treatment of the latent infection is also easier, less costly, and less toxic than treating active TB disease.

In 2018, The World Health Organization released new guidelines on the programmatic management of LTBI that harmonised preventative screening and treatment protocols in countries with high and low TB burden and regardless of country income. In the new guidelines, the WHO[5]:

  • Finds clear evidence for the benefit of systematic testing and treatment of LTBI
  • Supports IGRA (interferon-gamma release assay) testing globally for at-risk populations

The WHO places emphasis for latent TB testing on high-risk groups, including people living with HIV, household contacts of active TB cases, and patients receiving anti-TNF treatment.

Everyone has the right to know their TB status

Treatment regimes are becoming more streamlined, but they remain burdensome. Universal access to affordable diagnostics for latent TB will enable at-risk populations to make informed treatment decisions. Accurate TB testing also streamlines care, allowing providers to focus on true positives, reduce unnecessary treatment, and improve programmatic success.

[1] https://www.cdc.gov/tb/publications/factsheets/general/ltbiandactivetb.htm | [2] https://www.who.int/news-room/fact-sheets/detail/tuberculosis/ | [3] https://www.who.int/tb/post2015_strategy/en/ | [4] UN General Assembly. Political declaration of the high-level meeting of the General Assembly on the fight against tuberculosis. A/RES/73/3 | [5] World Health Organization. Latent tuberculosis infection – Updated and consolidated guidelines for programmatic management. WHO/CDS/TB/2018.4

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