Tuberculosis

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🧫 Tuberculosis (TB)

Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs (pulmonary TB) but can also spread to other parts of the body (extrapulmonary TB), such as the lymph nodes, bones, brain, kidneys, and spine.

TB spreads through the air when an infected person coughs, sneezes, or talks.

📋 Types of TB

TypeDescription
Latent TB InfectionBacteria are present but inactive; no symptoms; not contagious
Active TB DiseaseBacteria are multiplying; symptoms are present; contagious
Drug-resistant TBTB that doesn’t respond to standard drugs (e.g., MDR-TB, XDR-TB)

🧬 Causes & Transmission

  • Caused by Mycobacterium tuberculosis
  • Spread via inhalation of airborne droplets
  • Not spread through touching, sharing utensils, or surfaces

🩺 Symptoms of Active Pulmonary TB

  • Persistent cough (lasting more than 2–3 weeks)
  • Coughing up blood or sputum
  • Chest pain
  • Fever
  • Night sweats
  • Weight loss
  • Fatigue
  • Loss of appetite

⚠️ Symptoms may be milder in elderly or immunocompromised people (e.g., those with HIV/AIDS)

🔬 Diagnosis

  • Tuberculin Skin Test (TST / Mantoux test) – for latent TB
  • Interferon-Gamma Release Assays (IGRA) – blood test for TB infection
  • Chest X-ray – shows lung abnormalities
  • Sputum smear microscopy – detects acid-fast bacilli
  • Sputum culture – confirms TB and checks drug sensitivity
  • Molecular tests (e.g., GeneXpert MTB/RIF) – rapid detection and rifampin resistance

💊 Treatment

1. Latent TB

  • Isoniazid (INH) for 6–9 months
  • Alternative regimens: Rifampin or combination therapy (e.g., INH + rifapentine weekly)

2. Active TB (Drug-sensitive)

  • Standard regimen (usually for 6 months):
    • 2 months of HRZE:
      • H: Isoniazid
      • R: Rifampin
      • Z: Pyrazinamide
      • E: Ethambutol
    • Followed by 4 months of HR (isoniazid + rifampin)

💊 Treatment must be strictly followed to prevent resistance.

3. Drug-resistant TB

  • Requires longer, more complex regimens (up to 18–24 months)
  • May include second-line drugs (e.g., bedaquiline, linezolid)

🛡️ Prevention

  • BCG vaccine (mainly in TB-endemic countries; protects children)
  • Early detection and treatment of active cases
  • Infection control in healthcare settings (masks, ventilation)
  • Screening of high-risk groups (e.g., people with HIV, close contacts)

⚠️ Complications

  • Lung damage and respiratory failure
  • Spread to other organs (extrapulmonary TB)
  • Miliary TB (disseminated form)
  • Drug resistance (MDR-TB, XDR-TB)
  • Co-infection with HIV

🔄 Prognosis

  • Treatable and curable with full, proper antibiotic course
  • Without treatment, active TB can be fatal
  • Drug-resistant forms are harder to treat but manageable with specialist care

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