Tuberculosis in Children

Etiopathogenesis & Spectrum - Tiny Invader, Big Trouble

• Etiology: Mycobacterium tuberculosis (MTB), an acid-fast, obligate aerobic bacillus.
• Transmission: Primarily airborne via droplet nuclei from adults with sputum-positive pulmonary TB (PTB). Ingestion of unpasteurized milk (bovine TB) is rare.
• Pathogenesis: Inhalation → alveolar macrophage engulfment → lymphatic spread → Ghon focus (lung lesion) + regional lymphadenitis = Primary Complex.
• Spectrum:
  • TB Infection (latent): Positive TST/IGRA, no symptoms, normal CXR.
  • TB Disease: Symptomatic, abnormal CXR/findings.
    • Pulmonary TB: Primary complex, progressive primary disease, miliary TB.
    • Extrapulmonary TB (EPTB): Lymph node TB (most common EPTB), CNS TB, bone/joint TB.

⭐ Children, especially < 5 years, are more prone to disseminated forms (miliary TB, TBM) and rapid progression from infection to disease compared to adults due to immature immunity.

Clinical Clues & Red Flags - Spotting Sneaky Bug

• Persistent Cough: >2-3 weeks (cardinal symptom), often non-productive.
• Prolonged Unexplained Fever: >1 week, often low-grade, evening rise.
• Weight Loss/Failure to Thrive: Documented growth faltering.
• Fatigue/Lethargy: Reduced playfulness, easy tiredness.
• Contact Hx: Exposure to adult TB case = ⚠️ MAJOR RED FLAG.
• Extrapulmonary TB (EPTB) common:
  • Lymphadenitis (Scrofula): Painless, matted nodes (often cervical). Most common EPTB.
  • TB Meningitis (TBM): Insidious; headache, vomiting, irritability, seizures. ⚠️ High risk!
  • Abdominal: Pain, distension, doughy abdomen.
  • Skeletal (e.g., Pott's spine): Back pain, stiffness, deformity.
  • Miliary (Disseminated): High fever, hepatosplenomegaly, respiratory distress. CXR: "millet seed".
    • Fundoscopy: Choroidal tubercles.
• Other Clues:
  • No improvement with standard antibiotics for pneumonia.
  • HIV co-infection, severe malnutrition.
  • Erythema nodosum, phlyctenular conjunctivitis.

⭐ Choroidal tubercles on fundoscopy are pathognomonic for miliary TB.

Diagnostic Drill-Down - Unmasking the Culprit

• Screening:
  • Tuberculin Skin Test (TST): Induration ≥10mm (BCG unimmunized/ >1yr post-BCG); ≥5mm (HIV+, immunosuppressed, close contact, severe malnutrition).

    ⭐ A positive TST indicates TB infection, not active disease; clinical correlation vital.

  • IGRAs (Interferon-Gamma Release Assays): Preferred if BCG vaccinated.
• Microbiological Confirmation:
  • Specimens: Sputum (older children), Gastric aspirate/lavage (3x, young children), induced sputum.
  • AFB Smear (ZN stain): Rapid, low sensitivity.
  • Culture (LJ Medium): Gold standard, 4-8 weeks.
  • NAAT (CBNAAT/GeneXpert): Rapid (<2 hrs), detects M.tb & Rif-resistance. WHO recommended 1st test for all peds TB suspects.
• Imaging:
  • CXR: Hilar lymphadenopathy (commonest), Ghon complex, consolidation, miliary.

Treatment & Prevention - Kicking TB Out!

• Goal: Cure, prevent death/disability, cut transmission, prevent drug resistance. DOTS essential.

Drug-Sensitive TB (DS-TB): Daily Fixed-Dose Combinations (FDCs).

• New Cases:
  • Intensive Phase (IP): 2 months HRZE.
  • Continuation Phase (CP): 4 months HR.
  • Total: 6 months. Weight-band dosing.
• Severe forms (TBM, miliary): Longer CP (10 months HR), corticosteroids.

Drug-Resistant TB (DR-TB):

• Per National TB Elimination Program (NTEP) guidelines. Longer, specialized drugs.

Prevention:

• BCG Vaccination: At birth, 0.05 mL ID (<1m) / 0.1 mL ID (≥1m), left upper arm.
• TB Preventive Treatment (TPT):
  • Isoniazid (H) daily for 6 months for eligible contacts (<5 yrs, HIV+).
  • Alternative: 3HP (weekly H + Rifapentine for 3 months).
• Infection Control: Cough hygiene, ventilation.

⭐ BCG vaccine primarily protects against severe disseminated TB forms (e.g., meningitis, miliary) in children.

High‑Yield Points - ⚡ Biggest Takeaways

• Mantoux test (TST): 5 TU PPD-S; ≥10mm positive (≥5mm in HIV/contacts/malnourished).
• Gastric lavage/induced sputum for diagnosis (AFB, culture, NAAT).
• Primary progressive TB is common in children <5 years.
• Miliary TB & TB meningitis (TBM) are severe forms with high mortality.
• DOTS strategy: RHZE for intensive phase (2 months), followed by RH for continuation.
• BCG vaccine protects against severe forms (TBM, miliary), not primary infection.
• Contact tracing & Isoniazid prophylaxis for eligible contacts are vital.