Tuberculosis (TB) is an infectious disease and one of the top 10 causes of death worldwide.
In 2015, some 10.4 million people developed active TB and 1.8 million died as a result. However, an estimated 4.3 million were “missed” – most because they were never diagnosed at all and some because they were not linked to treatment and care.
Diagnosing TB remains a major challenge. The “gold standard” test is smear microscopy, which misses too many cases.
Simpler and more sensitive TB tests are urgently needed to avoid missing TB cases and to more easily diagnose TB in health facilities with limited laboratory infrastructure. We also need better tests to catch TB in children and in people living with HIV, who are more difficult to diagnose.
Read more about TB in the World Health Organization’s factsheet, here.
The diagnostic landscape
Rapid and accurate detection of TB and drug resistance is the essential first step in guiding treatment that can cure patients and prevent the ongoing spread of drug resistance. Diagnosis also enables disease monitoring and better targeting of interventions, which are essential in controlling TB transmission in populations.
It is estimated that approximately 4.3 million TB patients are ‘missing’, meaning they have not been diagnosed or received appropriate TB treatment. This is partly due to the lack of ready access to reliable and affordable TB diagnosis outside of major population centres. It is also partly due to the difficulty of diagnosing TB in some populations, such as children and people living with HIV, and the lack of TB drug susceptibility tests to guide appropriate treatment for patients whose TB is resistant to standard drugs.
TB diagnosis using older diagnostic techniques, such as microscopy, is still common, but the landscape is gradually changing. Since 2010, FIND and partners have worked to introduce and scale up the use of a WHO-recommended rapid molecular testing platform, the Gene Xpert, in clinical reference testing laboratories. The tool uses a simple cartridge system to diagnose TB as well as to detect specific mutations that are associated with resistance to rifampicin, a first-line TB drug. Rifampicin resistance generally indicates TB that is also resistant to at least one other TB drug and is a sign that second-line treatment will be needed because the usual first-line drugs won’t work.
More than 16 million Gene Xpert MTB/RIF cartridges have been procured since 2010 by 116 low- and middle-income countries at FIND-negotiated discount prices. As well, FIND works with national TB control programmes to provide implementation support and laboratory capacity building.
Still, even simpler, more robust, easy-to-use and more affordable tests are urgently needed, especially for use in decentralized health facilities and other places with limited laboratory infrastructure. Priority tests include: tests that can support more widespread diagnosis and triaging , tests that can detect when latent TB infections are becoming active, tests to rapidly determine drug susceptibility, and tests to simplify the diagnosis of TB in patients who are difficult to diagnose, including children and people living with HIV.
There are currently several test technologies in the TB diagnostics development pipeline; however, the pipeline is dominated by molecular tests and the search is ongoing for other biomarkers to meet some of the needs for better fit-for-purpose tests. Furthermore, product development companies face large funding hurdles: securing the financing to bring product manufacturing to scale and to conduct extensive clinical studies are common challenges.
Since 2003, FIND has promoted improvements in TB diagnostics and accelerated access to new diagnostic tools by working directly with health ministries to develop locally appropriate solutions based on international best practices.
FIND’s strategic approach for TB from 2015-2020 builds on this work and is guided by a vision of the future in which all people affected by TB have access to fit-for-purpose diagnostics and are linked to treatment. In pursuit of this vision, FIND’s activities are focused around four key objectives:
- Cutting transmission through early detection
- Providing correct treatment through early drug susceptibility testing (DST), preventing antimicrobial resistance and decreased morbidity and mortality
- Maximizing the impact of available TB diagnostics through comprehensive, country-specific solutions
- Demonstrating the vital role of diagnostics in controlling TB
These activities are conducted with a wide range of partners from companies, academic and research institutions, international organizations, health ministries and civil society organizations.