What is tuberculosis?

Tuberculosis (TB): Causes, Symptoms, Diagnosis, Treatment & Prevention

Introduction

Tuberculosis (TB) is a potentially serious infectious disease that primarily affects the lungs but can also spread to other parts of the body such as the brain, kidneys, and spine. Caused by the bacterium Mycobacterium tuberculosis, TB remains one of the top 10 causes of death worldwide, especially in low- and middle-income countries.

Despite being curable and preventable, TB continues to pose a global public health challenge due to drug resistance and inadequate access to healthcare. This article covers everything you need to know about TB, including its types, causes, symptoms, diagnosis, treatment, and prevention strategies.

What is Tuberculosis?

Tuberculosis is a bacterial infection that spreads through airborne droplets when an infected person coughs, sneezes, or speaks. It most commonly affects the lungs (pulmonary TB), but extrapulmonary TB can involve other organs.

There are two main TB conditions:

  • Latent TB infection (LTBI): The person carries the bacteria but shows no symptoms and is not contagious.

  • Active TB disease: The person has symptoms and can spread the infection.

Causes of Tuberculosis

TB is caused by the bacterium Mycobacterium tuberculosis. It spreads through:

  • Inhalation of airborne droplets from a person with active pulmonary TB.

  • Close and prolonged contact with infected individuals.

  • Weakened immune systems (due to HIV, diabetes, malnutrition, etc.).

Types of Tuberculosis

  1. Pulmonary TB:

    • Most common form.

    • Affects the lungs.

    • Highly contagious.

  2. Extrapulmonary TB:

    • Affects other organs like:

      • Lymph nodes

      • Bones and joints

      • Kidneys

      • Brain (TB meningitis)

      • Spine (Pott’s disease)

  3. Miliary TB:

    • A rare, severe form where TB bacteria spread through the bloodstream.

    • Can affect multiple organs simultaneously.

Symptoms of Tuberculosis

Pulmonary TB:

  • Persistent cough (lasting more than 2–3 weeks)

  • Coughing up blood (hemoptysis)

  • Chest pain

  • Fatigue and weakness

  • Night sweats

  • Fever and chills

  • Unintended weight loss

  • Loss of appetite

Extrapulmonary TB:

Symptoms vary depending on the organ involved, such as:

  • Swollen lymph nodes (lymphadenitis)

  • Back pain (spinal TB)

  • Headache and altered mental status (TB meningitis)

  • Painful urination or hematuria (renal TB)

Risk Factors

  • HIV/AIDS

  • Diabetes

  • Malnutrition

  • Smoking

  • Substance abuse (alcohol, drugs)

  • Close contact with an infected person

  • Living in crowded or poorly ventilated settings (prisons, shelters)

  • Healthcare workers exposed to TB patients

Diagnosis of Tuberculosis

1. Tuberculin Skin Test (Mantoux Test)

  • A small amount of tuberculin is injected under the skin.

  • A raised bump after 48–72 hours may indicate exposure.

2. Interferon-Gamma Release Assays (IGRAs)

  • A blood test that measures immune response to TB bacteria.

3. Sputum Test (AFB Smear and Culture)

  • Detects acid-fast bacilli in coughed-up mucus.

4. Chest X-ray / CT Scan

  • Identifies lung damage or cavities caused by TB.

5. Molecular Tests (e.g., GeneXpert MTB/RIF)

  • Detect TB DNA and drug resistance (especially to rifampicin).

6. Biopsy or fluid aspiration

  • For extrapulmonary TB: lymph node biopsy, pleural fluid analysis, etc.

Treatment of Tuberculosis

1. First-line Anti-TB Medications (for drug-sensitive TB):

  • Isoniazid (INH)

  • Rifampicin (RIF)

  • Ethambutol (EMB)

  • Pyrazinamide (PZA)

Treatment Duration:

  • 6 months total:

    • Intensive phase (2 months): All 4 drugs

    • Continuation phase (4 months): INH + RIF

2. Drug-Resistant TB (MDR-TB/XDR-TB):

  • Requires second-line medications (e.g., fluoroquinolones, linezolid, bedaquiline)

  • Longer treatment (9–20 months or more)

  • Directly Observed Therapy (DOT) is often used to ensure adherence.

Complications of TB

  • Lung damage or scarring

  • Respiratory failure

  • Spread to other organs (disseminated TB)

  • TB meningitis or brain damage

  • Spinal deformities (Pott’s disease)

  • Drug side effects (hepatitis, neuropathy)

  • Death (if untreated)

Prevention of Tuberculosis

  1. BCG Vaccination

    • Bacille Calmette-Guérin (BCG) vaccine is given to infants in many countries to prevent severe TB in children.

  2. Early Diagnosis and Treatment

    • Prompt treatment reduces the spread.

  3. Isolation of Infectious Cases

    • Especially during the early stage of treatment.

  4. Improved Ventilation

    • Reduces the concentration of TB bacilli in indoor air.

  5. Use of Personal Protective Equipment (PPE)

    • N95 masks for healthcare providers and caregivers.

  6. Public Health Measures

    • Contact tracing and TB screening programs

    • Health education in high-risk communities

Tuberculosis and HIV

  • TB is the leading cause of death among people with HIV.

  • HIV weakens the immune system, increasing the risk of active TB.

  • TB-HIV co-infection requires coordinated treatment of both diseases.

Global Impact and Statistics (2024–2025)

  • Around 10.6 million people fell ill with TB in 2023.

  • An estimated 1.3 million deaths occurred among HIV-negative people.

  • WHO’s End TB Strategy aims to reduce TB deaths by 90% by 2035.

Frequently Asked Questions (FAQs)

Q1: Is tuberculosis contagious?

Yes. Pulmonary TB can spread through airborne droplets. Extrapulmonary TB is generally not contagious.

Q2: Can TB be cured completely?

Yes. With proper antibiotic treatment, most TB cases can be cured.

Q3: Is latent TB dangerous?

Latent TB is not contagious, but it can become active if the immune system becomes weakened.

Q4: How long does TB treatment take?

Standard treatment takes 6 months, but drug-resistant cases may take up to 24 months.

Q5: Can you get TB again after treatment?

Yes. Reinfection or relapse is possible, especially in high-risk settings or with weakened immunity.

Conclusion

Tuberculosis is a serious yet preventable and curable infectious disease. Early diagnosis, proper treatment adherence, and public health efforts are vital to reducing the burden of TB worldwide. Continued awareness, access to healthcare, and preventive strategies like vaccination and improved living conditions can help bring an end to TB.

References

  1. World Health Organization (WHO) – www.who.int

  2. Centers for Disease Control and Prevention (CDC) – www.cdc.gov/tb

  3. National Tuberculosis Control Program, Pakistan – ntp.gov.pk

  4. Kumar & Clark’s Clinical Medicine

  5. Harrison’s Principles of Internal Medicine


Location: Pakistan

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