Tuberculosis (TB) is a communicable disease that is a major cause of ill health and one of the top 10 causes of death worldwide. According to WHO, in 2019, a total of 1.5 million people died worldwide because of TB. It is a major concern for the UN, which aims to end the TB epidemic by 2030.

Drug-resistant TB is a growing threat and poses another serious challenge to controlling the spread of the disease. WHO data show that India accounts for a quarter of all global and multi-drug-resistant TB (MDR-TB) cases. In many cases, the patient goes undiagnosed due to lack of proper screening tests and infrastructure and, in some cases, even if they are diagnosed, the patients do not get the right treatment or proper counselling with respect to the medication process. Unfortunately, only 58 per cent of overall estimated new and relapsing TB cases are notified in India.

According to the latest WHO report, the number of people who were provided with TB preventive treatment had increased four-fold, from one million in 2015 to over four million in 2019. However, the Covid-19 pandemic threatens to negate the gains made over recent years. The impact of the pandemic on TB services has been severe since there is sharp decrease in TB notifications in 2020 in India.

Missing patients

The ‘India TB Report 2020’, issued by the Ministry of Health and Family Welfare (MoHFW), , reveals that up to four lakh TB patients went missing or unreported. This is a large number and is a matter of grave concern given that the government wants to implement the plan of eradicating TB from India by 2025. There is an urgent need for both private and public healthcare sectors to collaborate and build a strong surveillance system with a proper framework for notifying new, existing, missing and relapsed patients.

Early diagnosis followed by prompt and appropriate treatment are vital for ending TB. Although smear remains the mainstay for diagnosis in resource poor countries, it cannot easily differentiate between Mycobacterial species. Culture-based identification, although the gold standard, is time-consuming, requiring 2–6 weeks to produce results.

The WHO recommends the use of Nucleic Acid Amplification Tests (NAATs) as the initial diagnostic test for TB. Among the currently available NAATs, the Xpert MTB/RIF Assay (CB-NAAT), the LINE Probe Assay (LPA) and the Loop-Mediated Isothermal Amplification (LAMP) are endorsed by the WHO for in vitro diagnosis of TB. These tests are excellent for rapid detection of Mycobacterium tuberculosis and screening of drug resistance.

However, there is still a gap in the market that accurately profiles drug resistance mechanism for the causative organism in a TB patient, which can help the treating clinician take informed decision on which treatment regimen to be prescribed. While phenotypic drug susceptibility test provides physical proof of whether the drug will act or not on a culture grown from the patient’s sample, sophisticated molecular techniques provide a much more detailed view of the infection.

This has led to the development of a test called SPIT-SEQ. It sequences the entire genome of the causative organism from the sputum sample directly and performs drug resistance profiling. In a country with a significant number of MDR-TB patients, SPIT SEQ is an ideal solution.

Just like many other infectious diseases, TB has also been sidelined due to the Covid pandemic. However, the pandemic did teach us the importance and need for faster and accurate molecular diagnostics and the infrastructure required for it. This pandemic has also shown how governments, public and private healthcare organisations and professionals have come together in the battle against the virus. Thus the lessons learnt from the pandemic should be applied to TB as well.

The writer is CEO, MedGenome Labs

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