1 out of 4 global cases of TB happen in India. The World Health Organization (WHO) End TB Strategy” aims to reduce TB incidence by 90% and TB deaths by 95% by 2035 compared to 2015 levels. India has committed to eliminating TB by 2025 under the National TB Elimination Programme (NTEP), through expanded diagnostics, universal drug susceptibility testing, nutritional support schemes, and digital adherence monitoring. Lets learn about TB and how we can all work together to end TB.
What is tuberculosis and what causes it?
Tuberculosis, commonly referred to as TB, is a disease caused by a bacteria called Mycobacterium tuberculosis. Tuberculosis mainly affects the lungs and is known as “pulmonary TB”, but it may attack other part of the body like the abdomen, uterus, spine etc, and is then known as “extra-pulmonary TB” Like the common cold, it spreads through the air from one person to another through the bacteria that are put into the air when a person with tuberculosis disease of the lungs or throat coughs or sneezes and people in proximity breathe in these bacteria and become infected. People who are infected with TB do not feel sick, do not have any symptoms, and cannot spread tuberculosis but they may develop the disease at some time in the future.
What is the difference between Tuberculosis infection and Tuberculosis Disease?
Anyone who is infected with the Mycobacterium tuberculosis bacilli has the TB germs in their body, but most people fight it with their immune system which protects them from developing TB disease and becoming sick. These people do not spread the disease to other people.
People who are infected with the TB germ have about a 5–15% chance of developing TB disease at some point in their life People who are infected with the TB germs will usually have the symptoms of the disease once they develop the disease Once a person has the tuberculosis disease, they also have a risk of death if not properly treated. They are also capable of spreading the disease to other people.
How many people are infected with tuberculosis and or have the disease?
It is estimated that 10.7–10.8 million new TB cases occurred globally in 2023-2024, with South-East Asia including India (45%), Africa (24%), and the Western Pacific (17%) bearing the highest burden. India accounts for 27% of this burden. The rate of deaths due to TB decreased to 21 per lakh population in 2024.
What are the types of tuberculosis disease?
Pulmonary TB: The bacteria mainly infect the lungs and show up with symptoms such as cough, chest pain, and difficulty breathing. This is the most common type of TB and spreads through droplets.
Extrapulmonary TB: The bacteria affect parts of the body outside the lungs, such as the kidneys, spine, lymph nodes, uterus and brain. This is generally not infectious.
Miliary TB: This is a severe and scattered form of the TB where the bacteria spread through the bloodstream to multiple organs.
Drug-resistant TB: Some strains of Mycobacterium tuberculosis have developed resistance to one or more of the antibiotics commonly used to treat TB. Drug-resistant TB poses additional challenges for effective treatment. This may be classified as MDR- Multi drug-resistant TB or XDR- Extremely drug-resistant TB.
Another way to classify TB is:
Latent TB infection: Primary infection is usually followed by the stage called latent TB infection where the immune system cells build a wall around lung tissue with TB bacteria. The bacteria can't do any harm as the immune system keeps them under control. The bacteria do survive but there are no symptoms during latent TB infection. Latent TB can last for many years, decades, or even an entire lifetime. In most individuals, the immune system keeps the bacteria inactive indefinitely.
Active TB disease: It happens when the immune system can't control an infection and bacteria cause disease throughout the lungs or other parts of the body. It may happen right after primary infection, but it usually happens after months or years of latent TB infection.
How does Tuberculosis spread?
TB spreads when a person with active lung TB talks, sings, coughs, or sneezes releasing TB bacteria in the air, in proximity of a susceptible individual.
TB does not spread through handshakes, using public toilets, sharing food and utensils, and casual contact. TB patients can continue living their normal lives after treatment completion.
Who can get tuberculosis?
A person of any race, age and income level can be infected with tuberculosis. The following conditions increase the risk of a person becoming infected with TB:
- Being in close contact with people with active TB disease
- Having an HIV infection
- Living in crowded unhygienic conditions
- Having malnutrition resulting in poorer immunity
- Being Homeless.
- Having Leukaemia or Hodgkin's disease
- Having severe kidney disease
A person’s risk of developing active TB mainly depends on how strong their immune system is. In some conditions, like AIDS, diabetes, drug addiction, or after an organ transplant, bone marrow transplant, CAR-T cell therapy, or long-term therapy with corticosteroids, the immune system is severely impaired which increases the chance of developing TB disease.
What are the symptoms of this disease?
A person with pulmonary TB may have any, all or none of the following symptoms:
- Persistent cough >3 weeks with phlegm +/- chest pain when one takes deep breaths or while coughing due to inflammation of the lungs.
- Coughing up blood.
- Unexplained weight loss.
- Low-grade fever or persistent fever, commonly associated with chills, especially during the afternoon or evening.
- Loss of appetite
- Tiredness
- Profuse sweating, particularly during the night known as Night Sweats, is a characteristic symptom of TB.
- Difficulty breathing and shortness of breath may happen if the infection has progressed and affected a significant portion of the lungs.
A person with extra-pulmonary TB may have the following general symptoms:
- Unexpected weight loss
- Fever
- Night sweats.
- Swollen lymph nodes may be visible in various parts of the body.
Other symptoms will depend on the organ or organs affected, for example:
- Swelling of the lymph nodes (retroperitoneal lymph nodes or lymph nodes located in the space behind the peritoneum which is the thin membrane lining the abdominal cavity. The retroperitoneal space contains organs such as the kidneys, pancreas, adrenal glands, parts of the intestines, and major blood vessels like the aorta get enlarged in abdominal TB)
- Joint pain and swelling (TB of joints/bones)
- Headache, fever, neck stiffness and drowsiness if one has TB meningitis.
- Infertility in case of TB of uterus
Symptoms of Active TB disease in children.
- Teenagers have symptoms similar to adult symptoms as described above.
- 1-12-year-olds: May have a persistent fever and weight loss.
- Infants: Baby may not grow as per age or gain weight as expected. The bay may also have symptoms from swelling in the fluid around the brain or spinal cord, which may include:
- Being sluggish or not active.
- Unusually fussy.
- Vomiting.
- Poor feeding.
- Bulging soft spot on the head.
- Poor reflexes.
In children and infants, TB often affects the lymph nodes, especially those in the neck (cervical lymph nodes). This form is called tuberculous lymphadenitis. The lymph nodes may become swollen, firm, and painless, and they may gradually increase in size over weeks.
Who should be tested for Tuberculosis?
People should be tested for TB if
- They have been in closed proximity of a person who is known or thought to have infectious TB disease
- They were born in or frequently travel to countries where TB disease is common
- They live or are employed in crowded setting where TB is more common like homeless shelters, prisons etc.
- They are a health care worker who look after patients with TB disease or work in labs or radiology units.
- They are living with HIV.
- They are a child who may have been in contact with someone with TB disease. Children, under 5, have a higher risk of developing TB disease once infected which makes it essential for them to be tested for TB infection if they have been in contact with someone with TB disease.
- People with medical risk factors like Immunosuppressive therapy (anti-TNF, transplant, long-term steroids), Silicosis or silica exposure and Dialysis patients.
These populations are prioritized for systematic screening programs, not only symptom-based testing according to WHO.
Should testing occur only when symptoms appear?
No. TB control depends on both passive and active screening.
Passive case finding - Test any person with symptoms suggestive of TB:
- Cough >2 weeks
- Fever
- Weight loss
- Night sweats
Active screening
- High-risk groups are screened even if they are asymptomatic to detect:
- Early active TB
- Latent TB infection
WHO specifically recommends systematic screening of contacts and other risk groups, even without symptoms.
| Group | Testing frequency |
| TB contacts | Immediately + repeat at 8–10 weeks |
| HIV patients | At every clinical visit |
| Healthcare workers | Baseline + after exposure (some centres annual) |
| Institutional residents | Entry + periodic screening |
| Immunosuppressed patients | Before starting therapy |
Guidance from Indian guideline perspective (NTEP):
Priority screening groups
- Household contacts of TB patients
- PLHIV
- Malnourished individuals
- Diabetes patients
- Elderly populations
- High-risk occupational groups
Contact screening
- Done within 2 weeks of index case identification
- Children <5 usually receive preventive therapy after ruling out active TB
What are the investigations done for diagnosing TB and where are they available?
The diagnosis of tuberculosis is usually done through a combination of clinical evaluation, imaging studies, and laboratory tests. Some are Minimum Standard Tests (as per GOI / NTEP guidelines) like CBNAAT, NAAT, Sputum smear microscopy, Sputum culture and Drug Susceptibility Testing (DST).
Tuberculin skin test (TST) or Mantoux test: A small amount of purified protein derivative (PPD) is injected under the skin. A positive reaction is indicated by a raised bump at the injection site. It suggests exposure to Mycobacterium tuberculosis and does not recognize whether the infection is latent, or it is active TB.
Interferon-gamma release assays (IGRAs): Blood tests, such as QuantiFERON-TB Gold or T-SPOT.TB, measure the release of interferon-gamma in response to TB-specific antigens. They are more specific tests and help to differentiate between latent and active TB.
Chest X-ray: It helps to identify any abnormalities in the lungs which may be seen as infiltrates, cavities, or other changes associated with pulmonary TB.
Sputum smear microscopy: A sample of sputum (mucus from the lungs) is examined under a microscope after staining to detect presence of the bacteria Mycobacterium tuberculosis. In India, to diagnose pulmonary TB, it is essential to get sputum examined on three consecutive days for TB bacteria. In the NCT of Delhi, DOTS centres have been established at many places where services provided are absolutely free.
Sputum culture: Sputum samples are cultured in a laboratory to allow the growth of Mycobacterium tuberculosis. This provides a confirmation of TB and thereafter the drug susceptibility testing can be done.
Nucleic acid amplification tests (NAATs): Polymerase chain reaction (PCR) and other molecular tests can detect the genetic material of Mycobacterium tuberculosis in the samples. This is a rapid and sensitive diagnostic method.
Xpert MTB/RIF assay: It is a molecular test that simultaneously detects Mycobacterium tuberculosis and assesses drug resistance to the main drug “rifampicin resistance”. The results take just a few hours leading to a quick diagnosis of TB and identification of drug resistance.
Bronchoscopy: In people with suspected extrapulmonary TB or in cases where the sputum samples are challenging to obtain, a bronchoscopy may be done to collect samples directly from the lower respiratory tract using a tube with a camera that is inserted into the airway.
Biopsy: For extrapulmonary TB, a biopsy of affected tissues or organs may be taken for microscopic examination and culture.
Drug susceptibility testing (DST): This test is used to find out the susceptibility of the TB bacteria to specific antibiotics which helps in guiding appropriate treatment.
What are the challenges of diagnosis of tuberculosis in children?
Diagnosis of TB in children is often challenging because their sputum smear is frequently negative and they may usually have vague and non-specific symptoms. For them these considerations are necessary:
- Extracting fluid from the stomach (gastric aspirate) or procuring sputum by patting their chest and making them cough for microbiological testing is helpful.
- Molecular diagnostics such as GeneXpert are used for samples from kids.
- There is a higher risk of disseminated TB and TB meningitis in children under 5 years.
Early detection is crucial to prevent severe complications.
What is the treatment of TB?
If a full course of anti-tubercular drugs is taken on a regular basis, this disease is fully curable. A TB patient has to take medicines for a minimum period of six months continuously. The drugs may continue up to one year in some cases. It is important that the drugs are discontinued only on the advice of the doctor. When patients do not take the complete treatment or take drugs on an irregular basis, their disease turns incurable or even life-threatening.
The usual treatment option for tuberculosis is DOTS (Directly Observed Therapy Short Course), which ensures that tuberculosis (TB) patients complete their treatment and be fully cured, This also helps prevent the spread of drug resistance in the community. The DOTS strategy, along with the other components of the Stop TB strategy, implemented under the Revised National Tuberculosis Control Programme (RNTCP) in India, is a comprehensive package for TB control, advocated by the WHO.
It is very important for the person to take the treatment for the prescribed duration, which is a minimum of 6 months. Stopping treatment earlier even if one feels better can lead to the bacteria becoming resistant to the drug administered and will require a stronger dose of the medicine to have effect.
The Standard Anti-Tubercular Treatment Regimen (only to be taken under medical supervision on being diagnosed and prescribed by a doctor):
Intensive Phase (First 2 months):
Isoniazid (H)
Rifampicin (R)
Pyrazinamide (Z)
Ethambutol (E)
Continuation Phase (Next 4 months):
Isoniazid (H)
Rifampicin (R)
Treatment of Drug-Resistant Tuberculosis
Drug-resistant TB occurs when the bacteria, Mycobacterium tuberculosis develops resistance to first-line anti-TB medications.
- MDR-TB (Multidrug-Resistant TB): Resistant to at least isoniazid and rifampicin
- XDR-TB (Extensively Drug-Resistant TB): MDR-TB with additional resistance to fluoroquinolones and second-line injectable drugs
To label the type of drug resistance a drug susceptibility testing (DST), molecular assays (CBNAAT/Xpert), or line probe assays is needed. The treatment is longer (9–24 months) and may include newer drugs such as bedaquiline and delamanid. Strict adherence is essential to prevent further resistance.
Is the disease of TB curable?
Yes, this disease is fully curable if the treatment is taken on a regular and continuous basis for adequate duration.
What are the side effects of TB drugs?
Not everyone has the side effects of TB drugs. Sometimes people on medication for TB may have adverse reactions to drugs, like nausea, vomiting, gastritis, itching etc. In this case, the patient should contact their doctor and not stop the treatment as incomplete treatment or missing doses can lead to drug resistance and not cure the disease.
The major adverse effects of the First-Line Anti-TB Drugs are:
- Isoniazid: Peripheral neuropathy (can be prevented with pyridoxine supplementation), toxicity of the liver.
- Rifampicin: Liver toxicity, orange discoloration of urine and body fluids.
- Pyrazinamide: Liver toxicity, increase in uric acid levels.
- Ethambutol: Inflammation of the Optic nerve (may cause visual disturbances, reduced colour vision)
How does one know whether they are responding to TB treatment?
The response to treatment is assessed by follow-up sputum examinations/culture done at regular intervals over the course of treatment. The sputum examination is also done at the end of the treatment to declare the patient cured.
The response in extra-pulmonary TB patients is assessed through improvement in symptoms and follow-up investigations such as X-rays, CT scans, etc. depending on what site is affected.
Is there a specific diet to be given to a person with tuberculosis disease?
One can eat any type of food as there are no special diets necessary for TB. As there is weight loss and loss of appetite in many cases, the diet should have adequate nutrition.
How can we prevent tuberculosis?
Tuberculosis can be prevented by reducing the transmission from person to person, identifying and treating latent and active infections, and addressing the possible risk factors. Key measures that can be taken to prevent tuberculosis are:
BCG vaccination: The Bacillus Calmette-Guérin (BCG) vaccine is used in many countries to prevent severe forms of TB in children. It may not provide complete protection against all forms of TB, but it helps to reduce the risk of severe complications.
Maintaining respiratory hygiene: Hygienic measures such as covering the mouth and nose when coughing or sneezing and try to use a mask while one is in congested public places like trains, buses, stations etc. helps in preventing aerosol spread of the bacteria.
Ventilation: Ventilating spaces by using a fan or open the windows for cross-ventilation of air, especially in crowded areas helps in reducing the concentration of infectious droplets in the air.
Early identification and treatment of latent TB infection: Screening of people at higher risk for TB, like those with known exposure to active cases or individuals with immunosuppression helps in timely treatment which prevents the progression to active TB.
Contact tracing and testing: Identification and testing of people who have been in close contact with someone diagnosed with active TB helps in early detection and treatment of latent or active TB in exposed people.
Public health education: Raising public awareness about TB transmission, symptoms, and the importance of seeking medical care help dilute the taboo. It educates the communities about the availability of testing and treatment services like the DOTS centre.
How can infection be controlled in the Community?
Effective TB control can only be done by taking precautions to prevent airborne spread of infection which can be done by:
- Using N95 masks in crowded spaces.
- Making sure homes have adequate natural ventilation.
- Practicing respiratory hygiene and cough etiquette and use of mask.
- Early diagnosis and initiation of therapy also significantly reduce the rate of infectivity.
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