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Lungs may still have scars left behind by tuberculosis, shows study

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Lungs may still have scars left behind by tuberculosis, shows study

The mere mention of tuberculosis scares many, considering it is one of the leading causes of death worldwide. Though the disease is curable by multi-drug therapy, increasing cases of drug-resistance in the causative bacteria remains a public health crisis. Mycobacterium tuberculosis, the bacteria that causes the infection, starts by affecting the lungs. While regular intake of anti-tuberculosis drugs can cure the disease in six months, does it reverse the harm that has already been done to the lungs?

In a recent study, researchers from Pune, along with their collaborators in Chennai and the USA, have assessed the functioning of lungs after successful tuberculosis (TB) treatment. The study, published in the journal PLoS ONE, has shown the occurrence of lung defects and chronic obstructive pulmonary disease after tuberculosis treatment. The study was partially funded by the Department of Biotechnology (DBT) and the Indian Council of Medical Research (ICMR).

The researchers studied 204 tuberculosis patients, including men and women, who had the infection for 20–60 days before starting treatment. They conducted multiple surveys and gathered data on the age, gender, socio-economic status, smoking and alcoholic habits, lifestyle, nutrition and disease history of the patients. They also conducted periodic clinical tests from the start of the treatment until a year after.

Lung functions of the patients were tested using spirometry. This test measures the volume of air inhaled and exhaled and the rate of breathing. The researchers gave bronchodilators—medicines that increase airflow—to patients with breathing difficulties. Participants with unsuccessful treatment, recurrent tuberculosis or a history of any other chronic lung diseases were excluded from the study.

The results showed that only 23% of the tested patients had a normal lung function. This number is alarming as most of the participants were young, and non-smokers, who were at much lower risk of lung damage. The study also found that about one in two participants had breathing difficulty, reduced lung capacity, and abnormal spirometry patterns. One-fourth of the participants had airflow obstruction, out of which, 50% had obstructive pulmonary disease. Although bronchodilators can treat airflow obstructions, only 21% of them showed a positive response.

Interestingly, the study found women to be at higher odds of having abnormal spirometry patterns and lung defects than men. The researchers attribute this observation to the long exposure that women have to household biomass fuels. The individuals with a history of tuberculosis were also found to have a lower life expectancy.

So, what can be done to mitigate such detrimental impacts on the lungs? The study puts forward many solutions. The easiest one is to avoid risk factors like smoking, constant exposure to toxic gases and fuels, diabetes, malnutrition and unhealthy Body Mass Index (BMI). Early diagnosis and treatment also help reduce the damage caused, say the researchers. Following up on tuberculosis treatment and periodic testing of lung functions also help.

The findings of the study show that the ill-effects of tuberculosis infection do not perish by merely treating it. The scar once left on the lungs stays throughout and haunts the individual with every breath one takes. The researchers hope that studies like theirs can help in bridging the knowledge gap about the impacts of chronic lung diseases in people who are not at a higher risk of diseases like tuberculosis.