The scourge of India

In 2016, 10.4 million people worldwide were diagnosed with TB, with 1.7 million people succumbing to the disease. As per the Global TB Report 2017, a whopping 26 per cent of these deaths (4.23 lakhs) were reported from India. The incidence of TB in India remains high—2.790 million patients in 2016. However, the incidence has declined during the 2000-2016 period—the rate (2016) stood at 211/100000 population/year. India led the world in the notification of new TB cases, with a 37 per cent increase during the 2013–2016 period. The issues of HIV/AIDS, and multi-drug-resistant tuberculosis (MDR-TB) further complicate TB control in India. The Government of India's initiative 'Revised National Tuberculosis Control Program' (RNTCP) is tasked with TB control in India. India allocated US$525 million for TB prevention, diagnosis, and control in 2017. Plans are afoot to carry out a national TB prevalence study in 2018.

Tuberculosis is caused by one of several bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). Of these, Mycobacterium tuberculosis is the most important causative agent. One-third of the world's population is infected with this bacterium. Those infected may either carry latent TB (these people do not feel sick, do not have any symptoms, can't spread TB, and are usually positive in PPD skin test) or show active disease. Symptoms of active TB include coughing that for lasts or more than 3 weeks, chest pain or coughing up of blood and sputum. Early symptoms may include unexplained weight loss, fever, fatigue, weakness, night sweats, chills etc. The infection spreads when you breathe TB bacteria shed into the air by a patient with the active disease. Such patients can spread the disease by coughing, sneezing, or simply talking. Approximately 10 per cent people with latent TB infection, go on to develop active TB disease. People with a compromised immune system (such as HIV/AIDS patients), those who inject illicit drugs, and who have past history of inadequately treated TB have an increased risk of progression towards active TB.

Diagnosis starts with a physical examination wherein a doctor examines your lungs with a stethoscope and checks your lymph nodes for swelling. The doctor may next order a chest X-ray or a CT scan which may show white spots (granulomas) in your lungs where your immune system has trapped TB bacteria. Should the chest X-ray be suggestive of TB, your doctor may take samples of your sputum (the mucus brought up by coughing). This is examined under the microscope, and also cultured to find out the strain of bacteria, and which antibiotics are effective. The most common TB test is a simple skin test called the Mantoux test. Nucleic Acid Amplification Tests are routinely used in TB diagnosis.

The treatment of TB is largely possible. It requires a close cooperation between the patient and the physician. The treatment involves taking one, or several different antibiotics. The most common antibiotics prescribed are Isoniazid (INH), Rifampin (RIF), Ethambutol, and Pyrazinamide. The side-effects of these drugs may include the lack of appetite, nausea, vomiting, abdominal pain, skin rashes, joint pain, blurred/changed vision, ringing in ears, hearing loss etc. However, it is dangerous to discontinue your TB drugs, or not take them regularly. The TB bacteria could continue to proliferate in your body, and even develop resistance to the prescribed drugs. Thus, drug-resistant TB evolves when you are infected with a TB strain that is resistant to one or more of the standard antibiotics. Drug-resistant TB is more frequently encountered in people who do not take their prescription drugs regularly or as prescribed, are in close contact with a patient with drug-resistant TB, have relapsed disease, or hail from areas where drug-resistant TB is common.

Patients resistant to isoniazid (INH) and rifampin (RIF) are said to harbour MDR-TB. In 2016, there were 147,000 such patients in India, with an incidence rate of 11/100000 population/year. Patients with MDR-TB are treated with several antibiotics each day for up to two years, but the mortality rate in such patients remains high. About 6.2 per cent of MDR-TB cases worldwide have extensively drug-resistant TB (XDR-TB). Patients with XDR-TB are resistant to at least four anti-TB drugs. Such patients in addition to being resistant to INH and RIF, are resistant to fluoroquinolones (such as levofloxacin or moxifloxacin) and to at least one second-line drug (amikacin, capreomycin or kanamycin). Once treatment of such patients is initiated, isolation is usually neither necessary nor appropriate.

Tuberculosis control shall entail a sustained commitment by scientific, political and social authorities in India. It is time to tackle this scourge on a war footing.

(Dr. Shalu Verma Kumar is Vice President, Quality Assurance, at CORE Diagnostics, India. The views expressed are strictly personal)