Ahead of World Tuberculosis Day, which is observed on March 24, the World Health Organization (WHO) has issued a new guidance for diagnosing drug-resistant tuberculosis, describing it as a “novel approach” that uses the “latest technologies”.

The UN health agency recommended the use of “a new class of diagnostic technologies: targeted next-generation sequencing (NGS) tests” in the third edition of “WHO Consolidated Guidelines on Tuberculosis. Module 3: Diagnosis - Rapid Diagnostics for Tuberculosis Detection”, replacing the 2021 document.

The “novel” technology -- targeted next-generation sequencing (tNGS) -- offers a higher resolution of the specific region of interest in the genome of the TB-causing bacteria, present in the patient’s sample, for analysing drug resistance compared to alternative sequencing methods. On the other hand, tests employing whole genome sequencing analyse the entire bacterial genome for drug resistance.

According to the World Health Organization (WHO), Multidrug-resistant TB (MDR-TB) is a public health crisis and a health security threat, with only about two in five people with drug-resistant TB accessing treatment globally in 2022.

Yet, despite the effectiveness of tNGS, the sophistication and complexity of the technology, coupled with the lack of manpower trained in analysing bioinformatics data, could pose a challenge for easy access to this technology in remote parts of India, Narayanan said.

Performing these tests will also require diagnostic labs to be equipped with sufficient data management and storage infrastructure, according to Chaitali Nikam, director (infexnTM) of HaystackAnalytics, a genomics-based diagnostics solutions provider. Accompanying the guidance, the WHO also launched a new TB sequencing portal hosting more than 56,000 sequences and representing “the most advanced sequencing and phenotyping knowledge base for Mycobacterium tuberculosis (the TB-causing bacteria)”.

A global study published in “The Lancet Infectious Diseases” journal earlier this week found that India, along with most of the world, failed to achieve WHO’s End TB milestones for 2020 -- including 20 per cent reduced TB incidence and 35 per cent fewer deaths, compared to the baseline figures of 2015.