Molecular diagnostic test will check for drug resistance

Beginning this month, health authorities will commence a nationwide programme to test every tuberculosis (TB) patient for signs of resistance to first-line drugs.

Other than providing a realistic assessment on the scale of resistance to commonly-available tuberculosis drugs, experts said this could also reveal a large number of hidden tuberculosis patients, as well greater numbers of those with multiple infections of TB and HIV (human immunodeficiency virus).

Even as India tops the world in the number of tuberculosis cases, the WHO (World Health Organisation) estimates that possibly as many as a million Indians with TB could be outside government scrutiny.

In 2015 alone, nine million Indians were tested for suspected tuberculosis and about 900,000 were confirmed to be ailing from it. Nearly 3% of new TB cases and 18% of prevalent cases are believed to be drug resistant, though independent analyses peg these numbers as much higher.

GeneXpert

The new policy, called the Universal Drug Sensitivity Test, which was formalised earlier this month, will be implemented using a molecular diagnostic test called GeneXpert, a US-developed technology tool being used worldwide since 2010. It can detect the TB bacterium as well check for resistance to rifampicin, one of the standard key TB drugs, within 90 minutes. Conventional tests take at least a day or more and require well-trained personnel for similar results.

States that will first see this policy being implemented include Arunachal Pradesh, Bihar, Goa, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Sikkim, Tripura and Uttarakhand. These, however, are not the States with the highest tuberculosis burden. “The States are expected to implement this intervention for patients diagnosed as on 1st August or later,” says a letter signed by Sunil Khaparde, who heads India’s National TB Control Programme.

The WHO’s TB statistics for India for 2015 — the latest available — gives an estimated incidence figure of 2.2 million cases of TB for India out of a global incidence of 9.6 million.

An inability to rapidly diagnose multi-drug resistant tuberculosis has long been identified as among the chinks in India’s strategy to eliminate tuberculosis. There are only around 600 GeneXpert devices now in use — roughly one for each district — and this posed a stumbling block to deploying the WHO-recommended kits earlier. “We now have enough of them to implement this in a big way, as well the [necessary] funds,” Mr. Khaparde told The Hindu. He did not specify numbers.

Optimising

GeneXpert kits, though one of their kind, are also known to be expensive, as well as requiring air-conditioned settings and reliable electricity access for optimal output. The Indian Council of Medical Research (ICMR) is in the process of testing a cheaper alternative to GeneXpert called Truenat MTB, which is reportedly more portable, battery-operated, and performs as well at lower costs.

“The TB burden is dramatically under-reported and, ideally, we should be moving to a system of molecular diagnostics for all TB suspects,” said Dr. Soumya Swaminathan, Director General, ICMR. “This is a significant move…we will likely find more cases and have to be prepared to treat more of them.”