New Delhi: India’s apex medical research body has recommended that Nontuberculous Mycobacterial (NTM) disease—a lung infection frequently mistaken for tuberculosis, and currently missed altogether by the country’s tuberculosis (TB) detection network—be formally screened and treated under the National Tuberculosis Elimination Programme (NTEP), the central government’s initiative to eradicate TB.
The recommendation comes from a new multi-centre study, funded by the Indian Council of Medical Research and published in The Lancet Regional Health – Southeast Asia, which flags NTM disease as an emerging public health problem that closely mimics TB.
TB is caused by the bacterium Mycobacterium tuberculosis. It mainly affects the lungs, though it can also involve other organs, and spreads through the air when a person with active TB coughs, sneezes or speaks.
NTM disease, on the other hand, is caused by Nontuberculous mycobacteria that are found in soil, water and dust and can cause a TB-like lung infection. If left untreated or misdiagnosed as TB, the infection can progressively destroy lung tissue, leading to respiratory failure.
The study was conducted between 2021 and 2025 across seven centres in New Delhi, Chandigarh, Ahmedabad, Wardha, Tirupati and Noida. It was coordinated by Jamia Hamdard in New Delhi, with molecular testing performed at the National Institute of Tuberculosis and Respiratory Diseases and Sharda University.
The researchers screened 71,143 people with presumptive TB—people who had symptoms such as a persistent cough, fever or weight loss and were being evaluated for tuberculosis. Of these, 230 (0.32 percent) actually had NTM disease—191 with pulmonary involvement and 39 with disease outside the lungs.
“Diagnosing and treating NTM disease early is important because, if left untreated, it can cause progressive lung damage, respiratory failure and even death,” said Dr S.K. Sharma, former head of the department of medicine at the All India Institute of Medical Sciences (AIIMS), New Delhi, and one of the study’s lead authors.
He said NTM requires a completely different treatment from TB, making an accurate diagnosis essential.
India accounts for nearly a quarter of the world’s TB cases, according to the WHO’s Global Tuberculosis Report 2025.
Dr Sharma, who chaired a national task force on TB control in medical colleges in 1998, said that though TB has come down significantly in the country over the decades, more people are living with lung damage caused by previous TB.
“The South Asian countries with a high TB burden, including India, are likely to see more NTM cases because healed TB often leaves permanent scarring in the lungs, making patients more vulnerable to these infections,” Dr Sharma said.
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Not TB, but often mistaken for it
NTM are a group of more than 200 bacteria found naturally in soil, water and dust. They are distant relatives of the TB-causing bacterium Mycobacterium tuberculosis but behave very differently.
Unlike TB, which spreads from person to person, NTM disease is generally acquired from the environment and usually affects people with weakened immunity, damaged lungs or other underlying health conditions.
“Around 75-80 percent of NTM infections affect the lungs and closely resemble TB, with symptoms such as persistent cough, fever, weight loss and similar chest X-ray findings,” said Vishwanath Upadhyay, a researcher from the Department of Molecular Medicine at Jamia Hamdard University in New Delhi and a co-author of the study
“In India, NTM cases are misdiagnosed as TB and patients are wrongly treated,” he told ThePrint.
According to Dr Sharma, NTM disease began receiving attention globally after the HIV epidemic in the early 1980s because people with HIV were particularly vulnerable to these infections. In India, some of the earliest documented cases were reported from Chennai, he said.
One important difference, Dr Sharma said, is that pulmonary NTM disease is generally not transmitted from one person to another, unlike TB. He added that because routine TB tests cannot reliably distinguish between the two infections, many patients receive anti-tuberculosis medicines for months before the correct diagnosis is made.
Past TB, the biggest risk factor
The study’s biggest finding is the strong link between past TB and future NTM disease. Among patients with NTM pulmonary disease, 80.6 percent had a previous history of pulmonary TB, making it by far the leading risk factor.
Dr Sharma explained that tuberculosis leaves behind scarred, damaged lung tissue, and that this damage becomes a natural site for NTM bacteria to take hold — describing old TB lesions as “a very good site” for the infection to reside and grow.
Chronic lung conditions like bronchiectasis, chronic obstructive pulmonary disease (COPD), smoking, diabetes, malnutrition and vitamin D deficiency were also flagged as contributing conditions.
“Doctors should have suspicion in patients with chronic respiratory symptoms who have previously been treated for TB but fail to improve or continue to deteriorate despite appropriate treatment,” Dr Sharma said.
He added that in such a situation, doctors should consider NTM disease instead of assuming it is another episode of TB or drug-resistant TB and conduct molecular tests to determine whether NTM is responsible.
Why the disease slips through the cracks
The study’s most striking number is the delay in diagnosis. Patients took, on average, more than seven months (221.8 days) between symptom onset and a confirmed NTM diagnosis.
Upadhyay attributed this to low clinical suspicion, since TB is far more common, and to the fact that routine tests used across India’s health system detect mycobacteria in general but cannot tell TB and NTM apart.
Confirming NTM requires more than routine TB tests. Doctors need repeated mycobacterial cultures, species identification using molecular tests such as line probe assays or genetic sequencing, and, in some cases, drug susceptibility testing.
These facilities are currently available mainly at specialised laboratories and tertiary care hospitals, limiting early diagnosis in many parts of the country.
According to Upadhyay, limited awareness among healthcare providers and restricted access to advanced diagnostics further contribute to these delays.
“Expanding access to rapid, affordable diagnostic tests and strengthening laboratory capacity will be essential for improving early diagnosis across India,” he said.
Longer, costlier treatment
Unlike TB, which has a standard six-month treatment, NTM treatment depends on the type of bacteria causing the infection. Patients are usually treated with a combination of antibiotics such as azithromycin, ethambutol and rifampicin, while some may also need injectable drugs like amikacin. Treatment often continues for 12 to 18 months and, in some cases, even longer.
Dr Sharma said there is no single treatment that works for all NTM infections. Some species are resistant to many antibiotics, making treatment more complex. He said identifying the exact species before starting treatment is essential because treatment differs depending on the bacteria involved.
Of 155 patients who started treatment in the study, 88.4 percent completed it successfully, though 18 had poor outcomes — nine deaths and nine lost to follow-up.
Experts also cautioned against the indiscriminate over-the-counter use of azithromycin, the backbone drug for NTM treatment, warning that casual, inadequate dosing for common coughs and viral fevers could breed drug resistance down the line.
The authors, including Dr Manjula Singh from the Department of Delivery Research at ICMR, have recommended integrating NTM screening into NTEP.
“Our study suggests that NTM disease is an under-recognised cause of illness among people being evaluated for TB in India. Although the overall proportion was relatively low (0.32 percent of more than 71,000 individuals with presumptive TB), affected patients experienced substantial diagnostic delays, and most had previous TB with persistent lung disease,” Dr Singh told ThePrint in a written response.
She added that the key message is not that every patient with suspected TB requires NTM testing. Rather, there should be greater awareness of NTM in appropriate clinical situations—particularly in patients with persistent symptoms, previous TB, or those who do not fit the usual pattern of TB.
“Earlier species-level diagnosis can help ensure that patients receive the correct treatment and avoid unnecessary anti-TB therapy,” she noted.
Based on these findings, she said, the study concludes that integrating rapid molecular diagnostics and guideline-based management for NTM within existing TB programme pathways could help reduce diagnostic delays and improve patient outcomes.
The researchers said that this would require stronger laboratory networks, greater awareness among clinicians and affordable indigenous diagnostic tests so patients receive the right diagnosis and the right treatment without delay.
Unlike TB, whose medicines are provided free under the government’s programme, NTM treatment often relies on expensive antibiotics that many patients cannot afford. Integrating NTM into NTEP could also improve access to treatment, Dr Sharma said.
(Edited by Sugita Katyal)