A study published online in the Lancet Infectious Disease journal has forecast an increase in drug-resistant tuberculosis cases in the four high-burden countries, including India, and suggested that person-to-person transmission will become the engine that drives drug-resistant tuberculosis in these countries.
By 2040, 12.4 per cent, or an eighth, of TB cases in India will be multi-drug-resistant, up from 7.9 per cent in 2000, says the study, by an international team of scientists. In the other three high-burden countries, multi-drug resistance will rise to 32.5 per cent of all cases in Russia, 8.9 per cent in the Philippines and 5.7 per cent in South Africa, respectively up from 24.8, 6 and 2.5 per cent in 2000.
Nearly 40 per cent of all drug-resistant TB cases occur in these four countries, accounting for more than 2,30,000 cases in 2015.
Globally, an estimated 10.4 million new cases of tuberculosis and 1.8 million deaths related to tuberculosis disease occurred that year. Multi-drug-resistant TB accounted for 480,000 cases, and 9.5% of these cases were estimated to be extremely drug resistant.
Of the multi-drug-resistant cases, one in 10 are expected to be extensively drug-resistant by 2040 — 9% in Russia and the Philippines, 8.9% in India, and 8.5% in South Africa — according to the study, based on a mathematical model using WHO data.
The study also estimates how many of these drug-resistant cases would be a result of non-resistant strains acquiring resistance during treatment. It predicts that fewer such cases will be caused by strains acquiring resistance — reducing from around 30% of cases of multi-drug-resistant tuberculosis in 2000 to 20-25% in 2040, and 80% of cases of extensively drug-resistant disease in 2000, to 50% in 2040.
Aditya Sharma of the US Centers for Disease Control and Prevention, said it isn’t enough to focus on curing people with TB or drug-resistant TB. “Even if we prevent new drug-resistant infections, there are enough current cases to keep the epidemic going. Drug-resistant TB will continue to be an increasingly dangerous threat so long as resistant strains spread through the air from one person to another,” PTI quoted Sharma as saying. “We must strengthen infection control measures, focus on households, health centres, and communities to prevent tuberculosis spreading from person to person, and develop more effective diagnostic tests to rapidly and accurately detect drug resistance.”
According to health ministry figures, India has 2.8 million cases of TB every year. Of these, 2.8 per cent are new cases of multi-drug resistance while another 11.2 are acquired cases of multi-drug resistance, Dr Sunil Khaparde, deputy director general in the health ministry’s Central TB division, told The Indian Express.
Reacting to the findings of the study in The Lancet, Dr Zarir Udwadia, chest physician with Hinduja Hospital in Mumbai, told The Indian Express, “All over the world and India is no exception, MDR-TB is acquired upfront due to primary transmission. It is indeed frightening, for it tells us the epidemic has entered a new and accelerated phase… You get MDR or XDR-TB on day-one by being exposed to a large numbers of active infectious patients in the community. Prompt diagnosis and treatment of these infectious-index cases is the only way to reduce the spread.”
According to Dr Madhukar Pai, associate director of McGill International TB Centre, Canada, the modelling study shows that MDR- and XDR-TB will become more common in the four given the current treatment regimens and control methods.
“However for India, the model is simplistic because it ignores the huge proportion of TB that is managed in the private sector with suboptimal diagnostics, widespread antibiotic abuse, and limited capacity to ensure adherence among TB patients. So, unless something is done about improving quality of TB care in the private sector, the situation for India might be worse than what is predicted by this modelling study,” Pai said.