Tuberculosis in Children

Intro & Epidemiology - Tiny Targets, Big Threat

• Mycobacterium tuberculosis infection in individuals < 15 years.
• India: Highest global pediatric TB burden (approx. 27% of world's cases); a major public health concern.
• Transmission: Primarily airborne droplets from an adult with active pulmonary TB.
• Risk factors: Malnutrition, HIV, household contact, age < 5 yrs.
• Young children (< 5 yrs) are more prone to rapid progression and severe forms like TBM or miliary TB.

⭐ Globally, an estimated 1.2 million children develop TB annually, with India contributing significantly to this burden (around 25-30%).

Pathogenesis & Clinical Forms - TB's Tiny Takeover

• Infection Pathway: Inhalation of MTB → Alveolar macrophages → Regional lymph nodes (hilar/mediastinal).
  • Ghon Focus: Initial lung lesion.
  • Ghon Complex: Ghon focus + lymphadenopathy.
  • Ranke Complex: Calcified (healed) Ghon complex.
• Immune Response: Cell-mediated immunity (CMI) critical; develops in 2-10 weeks. Granuloma formation contains bacilli.
• Progression Risk: ↑ in <5 yrs, malnutrition, HIV → active disease.

• Clinical Forms in Children:
  • Pulmonary TB (PTB): Primary complex common; cavitation rare. Miliary TB (hematogenous).
  • Extrapulmonary TB (EPTB) - More common than in adults:
    • Lymph Node TB: Most common EPTB (e.g., scrofula).
    • TB Meningitis (TBM): High mortality. Staged 1-3 (MRC).
    • Bone & Joint (Pott's spine), Abdominal, Disseminated.

  ⭐ Lymph node TB (especially cervical - scrofula) is the most common form of extrapulmonary TB in children.

• 📌 Primary complex, Extrapulmonary, Disseminated disease common in PEDiatric TB (vs. adult apical cavitation).

Diagnosis in Children - Cracking Kid Cases

• Challenges: Paucibacillary nature, non-specific symptoms, sputum collection difficulty.
• Key Pillars:
  • History: TB contact (crucial!), persistent cough >2wks, unexplained fever >1wk, weight loss/failure to thrive.
  • TST (Mantoux): Induration ≥10mm positive (irrespective of BCG); ≥5mm positive if HIV-infected, severely malnourished, immunosuppressed, or close contact with sputum-positive case. 📌 BCG Can Give Positive Test.
  • IGRAs (Interferon-Gamma Release Assays): More specific than TST, especially in BCG-vaccinated. Not routinely recommended for <5 yrs by IAP (Indian Academy of Pediatrics), consider if TST ambiguous.
  • Chest X-ray (CXR): Persistent hilar/paratracheal lymphadenopathy (commonest), miliary TB, consolidation, pleural effusion.
  • Microbiological Confirmation (Aim for this!):
    • Specimens: Gastric aspirate (GA) (≥2, ideally 3 consecutive morning samples), induced sputum, BAL, lymph node aspirate (FNA), pleural fluid, CSF, biopsy.
    • CBNAAT (Xpert MTB/RIF or Ultra): WHO-recommended initial test for pulmonary & EPTB. Detects M.tb & Rifampicin resistance rapidly.
    • AFB Smear: Low sensitivity in children (paucibacillary).
    • Culture (Solid/Liquid): Gold standard, highest sensitivity; drug susceptibility testing (DST).
• Scoring Systems: IAP Pediatric TB Guidelines Score useful when microbiological proof is lacking.
• Extra-pulmonary TB (EPTB): Diagnosis often relies on imaging (USG, CT, MRI) & microbiological/histopathological exam of specimen from affected site.

⭐ CBNAAT (Xpert MTB/RIF or Ultra) is the WHO-recommended initial diagnostic test for both pulmonary and most forms of extra-pulmonary TB in children, significantly improving case detection.

Treatment & Prevention - Kicking TB Out

• Strategy: DOTS essential. Pediatric weight-band FDCs.
• Drug-Sensitive TB (DS-TB) - Children:
  • IP: 2 months HRZE (Isoniazid, Rifampicin, Pyrazinamide, Ethambutol).
  • CP: 4 months HRE.
• Drug-Resistant TB (DR-TB) - Children:
  • Longer, complex regimens (e.g., shorter oral MDR-TB: 9-11 months).
  • Follow current NTEP guidelines.
• Adjunctive: Corticosteroids (TBM, pericardial TB).
• Prevention:
  • BCG Vaccine: At birth. Dose: 0.05 mL ID (<1mo), 0.1 mL ID (≥1mo). Protects vs severe TB.
  • TB Preventive Treatment (TPT):
    • Isoniazid (H) 6 months for contacts & high-risk (HIV+).
    • Shorter: 3HP (H+Rifapentine weekly x3mo), 3RH (H+R daily x3mo).

⭐ Rifampicin: potent CYP450 inducer (↓ OCP, ARV efficacy).

High‑Yield Points - ⚡ Biggest Takeaways

• BCG vaccine prevents severe TB forms (miliary, TBM), not primary infection.
• Mantoux test (TST): >10 mm positive; >5 mm in HIV/immunocompromised/malnourished children.
• Gastric aspirate/induced sputum for bacteriological confirmation in young children.
• Primary progressive disease is common in children under 5 years.
• Most common: Intrathoracic TB (hilar/paratracheal lymphadenopathy).
• Extrapulmonary TB (EPTB) is frequent; lymph node TB (scrofula) is most common EPTB.
• Standard regimen: 2HRZE + 4HR (DOTS); watch for Ethambutol ocular toxicity.