The right diagnosis for tuberculosis

We can detect TB largely by leveraging the systems already in place, as well as by quickly deploying newer proven technologies

March 25, 2024 02:41 am | Updated 12:22 pm IST

A TB patient receives medicines from a nurse at a hospital in Guwahati Assam.

A TB patient receives medicines from a nurse at a hospital in Guwahati Assam. | Photo Credit: AP

Tuberculosis, commonly known as TB, is a disease which continues to impact millions globally. Ending the TB epidemic by 2030 is among the health targets of the United Nations’ Sustainable Development Goals. Last year, Prime Minister Narendra Modi said that India is working towards eliminating TB five years ahead of the global 2030 target. This is an ambitious time frame. How well-positioned is India to achieve this?

A macro view suggests that India has done exceptionally well so far. A strong political intent is driving the right policies. In fact, in November 2023, the World Health Organization (WHO) acknowledged India’s success on two major fronts: in reducing TB incidence by 16% from 2015 to 2022 (close to double the pace at which global TB incidence is declining) and in reducing TB mortality by 18% during the same period, keeping in line with the global trend.

The weakest aspect

However, as Dr. Madhukar Pai, Dr. Puneet K. Dewan, and Dr. Soumya Swaminathan pointed out in ‘Transforming tuberculosis diagnosis’ in Nature, globally, diagnosis continues to be the “weakest aspect of TB care”. According to the WHO’s ‘Global Tuberculosis Report 2023’, for the first time globally, 7.5 million patients were diagnosed with TB in 2022; yet there remained a large gap of some 3.1 million people who probably fell ill with TB but were not diagnosed and reported to national TB programmes. As the article surmised succinctly, “If we cannot find TB, we cannot treat TB. And if we cannot treat TB, we cannot end TB”.

So, how do we find TB? We can detect it largely by leveraging and optimising the systems and processes already in place, as well as by quickly deploying newer proven technologies that take diagnosis as close to the point of care as possible.

Take, for instance, the first step of screening patients: India regularly conducts active case-finding drives across the country. But it will be useful to reassess the screening procedures in place. A recent Lancet study as well as the Indian Council of Medical Research’s ‘National TB Prevalence Survey in India’ showed that while screening people for symptoms is good, it is not substantive. Studies also show that in many cases, despite not showing any apparent symptoms, people may have infectious TB and may even be transmitting it.

X-ray imaging is a quick and efficient way to find these patients. X-ray technology has advanced dramatically. Now, we not only have portable hand-held devices, but also software driven by Artificial Intelligence that can read digital X-ray images and detect possible TB with a high degree of certainty. This must be used on a wider scale so that we can find and absorb potential patients into the care cascade faster.

While X-rays are good screening tools, it is imperative to detect TB bacteria in the patient with absolute certainty. The age-old sputum microscopy test has its limitations which are addressed by the newer molecular tests that are rapid, accurate, and even detect resistance against drugs. To be sure, India has scaled up molecular diagnostic capacity significantly. The NAAT (nucleic acid amplification test) machines in India have gone up from 651 in 2017 to more than 5,000 in 2022. But the utility of these tests is limited due to their high costs and issues with accessibility. Moreover, a large number of existing technologies including molecular testing are reliant on sputum collection and testing. This comes with its own challenges. First, it may not be as easy for everyone, especially young children, to produce sputum. Second, sample transportation, especially in remote and hilly districts, remains a challenge. During the COVID-19 pandemic, when an alternative to nasopharyngeal swabs was introduced in the form of simpler nasal swabs, saliva, and self-collection, the testing coverage greatly increased. We must therefore be on the lookout for newer technologies and approaches to diagnosis.

Other collection techniques

It is time to actively explore other collection techniques such as tongue swabs which can be a true game changer. Here, the sample is extracted by simply rubbing the swab in the oral cavity. This augments our point-of-care testing abilities and also reduces the costs for overall diagnosis of TB. We could also better utilise another invaluable resource: PCR machines, which served us well during the COVID-19 pandemic. These are already fitted with the right diagnostic technology and can get to the last mile across the country effectively. Newer technologies such as the urine LAM test can also be used to detect cases in the general population effectively. This is a rapid test which is easily performed. It can help in screening for both pulmonary TB (lungs) and extra-pulmonary TB (organs other than the lungs).

The TB diagnostics pipeline is rich with several new innovative tests on the anvil. However, to maximise these tests, their rapid validation and adoption under the programme is critical. To ensure we truly reach the last mile, point-of-care testing and diagnosis is imperative. The good news is we already have a diagnostic framework that is forward-looking. We need to simply improve implementation and be more proactive in deploying new technologies. We need to ensure that new technologies are streamlined and rolled out faster and build capacity at the sub-district level to conduct such tests as needed. Minor re-adjustments will make a major contribution to India’s TB elimination drive.

Sarabjit Chadha is Regional Technical Director, India and South-East Asia at FIND

0 / 0
Sign in to unlock member-only benefits!
  • Access 10 free stories every month
  • Save stories to read later
  • Access to comment on every story
  • Sign-up/manage your newsletter subscriptions with a single click
  • Get notified by email for early access to discounts & offers on our products
Sign in


Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.

We have migrated to a new commenting platform. If you are already a registered user of The Hindu and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.