Every year on March 24th, the world observes World Tuberculosis Day — marking the anniversary of Dr. Robert Koch's 1882 discovery of Mycobacterium tuberculosis, the bacterium that causes TB. Despite being preventable and curable, tuberculosis remains the world's deadliest infectious disease, killing approximately 1.6 million people annually. India bears the highest TB burden globally, accounting for approximately 28% of all TB cases worldwide.
What Is Tuberculosis?
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs (pulmonary TB) but can affect any organ in the body (extrapulmonary TB). TB spreads through the air when an infected person coughs, sneezes, or speaks. Not everyone exposed to TB develops active disease — approximately 25% of the world's population has latent TB infection (LTBI), where the bacteria are present but dormant and the person is not infectious.
Yes, TB Is Curable
This is the most important message of World TB Day. Drug-sensitive TB is curable with a standard 6-month course of antibiotics (isoniazid, rifampicin, pyrazinamide, and ethambutol). Treatment success rates exceed 85% globally when patients complete the full course. The challenge is ensuring that patients complete treatment — stopping early leads to drug resistance and treatment failure.
Drug-Resistant TB: The Growing Challenge
Drug-resistant TB (DR-TB) — including multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) — is a growing global health crisis. DR-TB develops when TB bacteria acquire mutations that make them resistant to standard antibiotics, typically due to incomplete or inadequate treatment. India has one of the highest burdens of MDR-TB globally. Treatment of DR-TB requires longer courses (18–24 months) of more toxic and expensive drugs, with lower success rates.
The Genetic Component of TB Susceptibility
Why do some people exposed to TB develop active disease while others don't? Genetics plays a significant role. Variants in immune regulation genes — including HLA genes, NRAMP1 (SLC11A1), VDR (vitamin D receptor), and IL-12 pathway genes — influence susceptibility to TB infection and progression from latent to active disease. Vitamin D deficiency, which is extremely common in India, impairs the immune response to TB — and VDR variants affect how effectively vitamin D activates anti-TB immunity.
Pharmacogenomics and TB Treatment
Genetic variants also affect how TB drugs are metabolized. NAT2 (N-acetyltransferase 2) variants determine whether a patient is a fast or slow acetylator of isoniazid — a key TB drug. Slow acetylators accumulate higher isoniazid levels and are at greater risk of isoniazid-induced peripheral neuropathy. Fast acetylators may need higher doses for adequate drug exposure. Pharmacogenomic testing can optimize isoniazid dosing and reduce side effects.
FAQs
How do I know if I have TB?
Symptoms of active pulmonary TB include persistent cough (>2 weeks), coughing blood, fever, night sweats, weight loss, and fatigue. If you have these symptoms, see a doctor immediately. TB is diagnosed by sputum microscopy, culture, and molecular tests (GeneXpert).
Is the BCG vaccine effective against TB?
The BCG vaccine provides good protection against severe forms of TB in children (TB meningitis, miliary TB) but variable protection against pulmonary TB in adults. It is given to all newborns in India as part of the national immunization program.
Understand Your Genetic Immune and Medication Profile
Genomepatri and MedicaMap by MapmyGenome include genetic insights into immune function and pharmacogenomics for key medications — helping you and your doctor make more informed decisions about disease susceptibility and treatment optimization.
