Understanding Tuberculosis: Causes, Symptoms, Diagnosis, and Treatment
Understand tuberculosis with this guide covering its causes, symptoms, diagnosis, and treatment options. Learn how TB spreads, who is at risk, available preventive measures, and why early detection is crucial for effective management and recovery.
Written by Dr. J T Hema Pratima
Reviewed by Dr. Rohinipriyanka Pondugula MBBS
Last updated on 16th Sep, 2025
TB is a contagious bacterial infection that primarily affects the lungs but can spread to other parts of the body. It is caused by the bacterium Mycobacterium tuberculosis and is both preventable and curable with proper treatment.
What Exactly is Tuberculosis?
Tuberculosis (TB) is an ancient infectious disease that continues to be a major global health concern, affecting millions every year. It is caused by a specific type of bacterium that has a unique, waxy coating, which makes it resistant to many common antibiotics and allows it to survive in the body for long periods.
The Bacterium Behind the Disease: Mycobacterium tuberculosis
The pathogen behind TB is the bacterium Mycobacterium tuberculosis. Its tough, waxy cell wall makes it resistant to many disinfectants and allows it to survive in airborne droplets for several hours. However, prolonged, close contact is usually required for transmission to occur; you typically cannot get it from brief handshakes or sharing a meal.
Latent TB Infection vs. Active TB Disease: A Critical Difference
This is the most important concept in understanding TB:
Latent TB Infection (LTBI): The bacteria are present in the body but are inactive, causing no symptoms. The immune system walls them off, making the person non-contagious. However, the bacteria are still alive and can become active later if the immune system weakens.
Active TB Disease: The bacteria multiply and cause illness. People with active TB in their lungs or throat are contagious. Symptoms include coughing, fever, and weight loss. Without treatment, active TB can be fatal.
Symptoms of Tuberculosis
Symptoms vary depending on whether the TB is in the lungs (pulmonary) or has spread to other organs (extrapulmonary).
Symptoms of Pulmonary Tuberculosis
A persistent cough that lasts for three weeks or longer
Coughing up blood or sputum (phlegm from deep inside the lungs)
Chest pain, or pain with breathing or coughing
Unintentional weight loss and loss of appetite
Fatigue and generalized weakness
Fever and chills
Night sweats
Symptoms of Extrapulmonary TB (Outside the Lungs)
TB can affect the kidneys, spine, brain, and lymph nodes. Symptoms depend on the organ involved:
TB in the spine: Back pain and stiffness.
TB in the kidneys: Blood in the urine.
TB in the brain (meningitis): Headaches and confusion.
TB in lymph nodes: Swelling, typically in the neck.
If you experience a persistent cough lasting more than two weeks, especially when accompanied by fever and weight loss, consult a doctor online with Apollo24|7 for further evaluation.
How Does TB Spread? Causes and Risk Factors
How Tuberculosis Transmission Occurs
TB is an airborne disease. It spreads through the air when a person with active pulmonary TB coughs, sneezes, speaks, or sings, releasing tiny droplets containing the bacteria. Others nearby can then inhale these droplets. It is not spread by touching surfaces, sharing food, or kissing.
Who is at a Higher Risk of Developing Active TB?
While anyone can get TB, certain factors significantly increase the risk of progression from latent to active disease:
Weakened Immune System: People with HIV/AIDS, diabetes, severe kidney disease, or certain cancers.
Medications: Those on immunosuppressant drugs, such as for organ transplants or autoimmune diseases.
Substance Abuse: Tobacco smoking and intravenous drug use.
Healthcare Workers: Those frequently exposed to untreated patients.
Malnutrition and living in crowded, poorly ventilated conditions.
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Getting a Diagnosis: How is TB Detected?
Diagnosing TB involves a combination of tests to confirm the presence of the bacteria.
The Tuberculin Skin Test (TST)
Also known as the Mantoux test, a small amount of fluid is injected under the skin. The arm is checked 48-72 hours later for a raised, hard bump. A large bump indicates a likely TB infection, but it cannot distinguish between latent and active disease.
Interferon-Gamma Release Assays (IGRA Blood Test)
This blood test measures the immune system's reaction to TB bacteria. It is more specific than the skin test and is not affected by prior BCG vaccination. It's often used to confirm a positive skin test.
Imaging Tests: Chest X-rays and CT Scans
If a skin or blood test is positive, a chest X-ray is used to look for spots or shadows in the lungs that suggest active TB disease. A CT scan can provide more detailed images if needed.
Sputum Smear and Culture Tests
This is the gold standard for confirming active pulmonary TB. Sputum samples (mucus from the lungs) are collected and examined under a microscope for TB bacteria (smear test) and then grown in a lab (culture test) to confirm the diagnosis and test which antibiotics will work. Apollo24|7 offers convenient home collection services for tests like sputum culture and other diagnostic needs.
Effective Tuberculosis Treatment and Management
TB is curable with the right antibiotics taken for the correct amount of time.
Treating Latent TB Infection to Prevent Active Disease
Treatment for latent TB usually involves taking one or two antibiotics for 3-9 months. This is crucial for preventing the infection from becoming active, especially in high-risk individuals.
The Standard Drug Regimen for Active TB
Treating active TB disease requires a combination of several antibiotics (typically isoniazid, rifampin, ethambutol, and pyrazinamide) for at least 6 months. It is vital to complete the entire course of medication, even after symptoms improve, to ensure all bacteria are killed and to prevent the development of drug-resistant TB.
The Importance of DOTS (Directly Observed Therapy)
To ensure adherence, many public health programs use DOTS, where a healthcare worker watches the patient take every dose of their medication. This strategy is highly effective in curing patients and preventing the spread of drug resistance.
The Growing Challenge: Drug-Resistant TB (MDR-TB and XDR-TB)
When TB bacteria become resistant to the drugs used to treat them, it creates a major public health crisis. This happens primarily due to incomplete or incorrect treatment.
Multidrug-Resistant TB (MDR-TB): Resistant to at least isoniazid and rifampin, the two most potent first-line drugs.
Extensively Drug-Resistant TB (XDR-TB): A rarer type of MDR-TB that is also resistant to fluoroquinolones and at least one second-line injectable drug.
Treatment for drug-resistant TB is longer (up to 2 years), more complex, has more side effects, and is less effective.
Prevention Strategies: How to Protect Yourself and Others
The BCG Vaccine: Uses and Limitations
The Bacille Calmette-Guérin (BCG) vaccine is used in many countries with high TB prevalence to protect infants and young children from severe forms of TB, like TB meningitis. It is not widely used in adults because its effectiveness against pulmonary TB in adults is variable.
Public Health and Infection Control Measures
The key to stopping the spread of TB is:
Early diagnosis and complete treatment of active cases.
Ventilation: Ensuring good airflow in living and working spaces.
Respiratory hygiene: Covering the mouth when coughing.
Infection control in healthcare settings, including the use of specialized masks (N95 respirators).
Conclusion
Tuberculosis remains a significant global health challenge, but it is one we are equipped to fight. The power to combat TB lies in a combination of robust public health systems, scientific advancement, and individual awareness. Understanding the critical difference between latent and active infection, recognizing the symptoms early, and committing to complete treatment are the cornerstones of effective TB control. While the rise of drug-resistant strains presents a serious hurdle, ongoing research and strict adherence to treatment protocols offer hope. If you suspect you may have been exposed to TB or are experiencing symptoms, the most important step you can take is to seek professional medical advice promptly. Remember, tuberculosis is preventable, treatable, and curable.
Consult Top Specialists
Consult Top Specialists
Dr. P Sravani
Pulmonology Respiratory Medicine Specialist
3 Years • MBBS, MD
Visakhapatnam
Apollo Clinic Vizag, Visakhapatnam
Dr. Hyder
Pulmonology Respiratory Medicine Specialist
5 Years • MBBS, MD (PULMONOLOGY)
Guntur
Kalam chest and multi-speciality clinic, Guntur
Dr Rakesh Bilagi
Pulmonology Respiratory Medicine Specialist
10 Years • MBBS MD PULMONOLOGIST
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
Dr. E Prabhakar Sastry
General Physician/ Internal Medicine Specialist
40 Years • MD(Internal Medicine)
Manikonda Jagir
Apollo Clinic, Manikonda, Manikonda Jagir
(125+ Patients)
Dr. K Prasanna Kumar Reddy
Pulmonology Respiratory Medicine Specialist
16 Years • MBBS, DTCD (TB&CHEST), DNB (PULM MED), FCCP
Hyderabad
Apollo Medical Centre Kondapur, Hyderabad
