---

Pulmonary Tuberculosis in Children

---

1. Epidemiology

• Childhood TB is largely a marker of failure of TB control in adults - children are exposed via infectious adult contacts, especially smear-positive parents or household members.
• Children under 5 years are most vulnerable; up to 20% of exposed infants develop disease within 2 years of infection.
• The commonest age of childhood TB disease is 1-4 years.
• Risk is higher in urban, low-income populations; immigrants, refugees, and international adoptees are disproportionately affected.
• Children rarely have smear-positive TB and are not significant sources of transmission.
• A diagnosis of TB infection (TBI) or TB disease in a young child is a public health sentinel event, often representing recent community transmission. - Red Book 2021, p.1214

---

2. Pathogenesis

• Transmission is via airborne droplet nuclei produced by an adult/adolescent with contagious pulmonary, endobronchial, or laryngeal TB.
• After inhalation, bacteria reach alveoli and are taken up by macrophages. Cell-mediated immunity (CMI) develops over 2-10 weeks - this is when the TST/IGRA becomes positive.
• Primary (Ghon) complex forms: a sub-pleural focus + regional lymphadenopathy. In most children this heals without progression.
• Young age, immunodeficiency, malnutrition, and HIV increase the risk of progressive primary disease or dissemination (miliary TB, TB meningitis).

---

3. Risk Factors for Progression from Infection to Disease

---

4. Clinical Features

• Persistent fever >= 2 weeks without a known cause
• Unremitting cough >= 2 weeks
• Weight loss of >= 5% in 3 months or failure to gain weight over 3 months
• Night sweats, fatigue, loss of appetite
• Lymphadenopathy (hilar, mediastinal, cervical)

Important: Infants and young children may have non-specific symptoms (poor feeding, failure to thrive) without prominent respiratory symptoms. Classic adult features (cavitation, haemoptysis) are rare in children.

• Bronchial compression by enlarged lymph nodes
• Pleural effusion
• Miliary spread (especially in infants < 12 months - always do lumbar puncture to rule out TB meningitis in this age group)

---

5. Diagnosis

5a. Approach

"Diagnosis of tuberculosis should not be made only on clinical features, and further investigations are always necessary." - Park's Textbook

5b. Diagnostic Algorithm (RNTCP/IAP)

1. Start with CBNAAT (Xpert MTB/RIF) on sputum - preferred test
2. If MTB detected → Microbiologically confirmed TB
3. If MTB not detected or sputum unavailable → proceed to Chest X-ray + TST (Mantoux)
4. X-ray highly suggestive (miliary, lymphadenopathy, fibrocavitatory) → collect gastric aspirate or induced sputum for CBNAAT
5. X-ray non-specific shadows + TST negative → trial of antibiotics (NOT quinolones, linezolid, or Amox-clav as these have anti-TB activity); if shadows persist, collect GA/IS for CBNAAT
6. X-ray normal + TST positive → Evaluate for extrapulmonary TB; refer to expert
7. X-ray normal + TST negative → Look for alternative diagnosis

5c. Specimen Collection

• Children > 2 years and adolescents: induced sputum (nebulised hypertonic saline)
• Children unable to produce sputum: early-morning gastric aspirate (GA) via nasogastric tube, before ambulation or feeding - collected on 3 separate mornings for AFB stain and culture
• Bronchial washing or bronchoalveolar lavage if available
• Fluorescent staining (auramine) is preferred over traditional Kinyoun acid-fast smear

"The best specimen for diagnosis of pulmonary TB in any child or adolescent in whom cough is absent or nonproductive and sputum cannot be induced is an early-morning gastric aspirate." - Red Book 2021, p.1221

5d. TST (Mantoux) Interpretation in Children

• Intradermal injection of 2 TU of PPD RT-23 (India) or 5 TU PPD-S (USA); read at 48-72 hours
• Positive cutoffs:

• BCG vaccination does not contraindicate TST, but IGRA is preferred in BCG-vaccinated children to avoid false positives.
• TST/IGRA positivity indicates infection (TBI), not necessarily active disease. Chest X-ray and clinical evaluation are required to distinguish TBI from active disease.

5e. IGRA (Interferon-Gamma Release Assay)

• Examples: QuantiFERON-TB Gold Plus, T-SPOT.TB
• Not recommended for children < 2 years (limited data)
• Preferred over TST in BCG-vaccinated children
• Cannot distinguish TBI from active disease

5f. Chest X-Ray Findings

---

6. Treatment

6a. Drug-Susceptible Pulmonary TB (First-Line)

• If cavitation on CXR or sputum culture positive at 2 months → extend to 9 months
• If only hilar adenopathy with no drug resistance risk → 3-drug regimen (HRZ x 2 months, then HR x 4 months) may be used by some experts
• DOT (Directly Observed Therapy) is strongly recommended for all children and adolescents

"A 6-month, 4-drug regimen... is recommended for treatment of pulmonary disease, pulmonary disease with hilar adenopathy, and hilar adenopathy disease in infants, children, and adolescents." - Red Book 2021, p.1230

6b. Paediatric Doses (WHO/RNTCP)

6c. Special Situations

---

7. TB Preventive Therapy (Chemoprophylaxis)

• a. All asymptomatic contacts < 6 years of a smear-positive case, regardless of BCG status (after ruling out active disease)
• b. All HIV-infected children with known TB exposure or TST >= 5 mm, without active disease
• c. All TST-positive children on immunosuppressive therapy (nephrotic syndrome, acute leukemia, etc.)
• d. Newborns of mothers diagnosed with TB in pregnancy - 6 months of prophylaxis, then BCG vaccination

---

8. BCG Vaccination

• BCG (Bacille Calmette-Guerin) is given at birth in high-burden countries (India's Universal Immunization Programme).
• Protects against miliary TB and TB meningitis in young children (up to 80% efficacy for severe forms).
• Does NOT reliably prevent pulmonary TB in adults.
• BCG does not eliminate the need for TB chemoprophylaxis in high-risk contacts.

---

9. Drug-Resistant TB in Children - Key Principles

1. Always treat in consultation with an expert
2. Include at least 4-6 bactericidal drugs to which the strain is susceptible
3. Never add a single drug to a failing regimen
4. Treat for at least 12 months after culture conversion (24 months if HIV+)
5. Bedaquiline and delamanid are options for pre-XDR/XDR-TB in older children

---

10. Monitoring During Treatment

• Monthly clinical assessment and weight measurement
• CXR at 2 months and end of treatment
• Monthly sputum culture if microbiologically confirmed
• Watch for drug toxicity: isoniazid (hepatotoxicity, peripheral neuropathy), rifampin (hepatotoxicity, orange body fluids), ethambutol (optic neuritis - use with caution in young children who cannot report visual changes), pyrazinamide (hepatotoxicity, hyperuricaemia)

---

Sources

• Red Book 2021: Report of the Committee on Infectious Diseases, AAP - pp. 1214-1238
• Park's Textbook of Preventive & Social Medicine - Paediatric TB section
• Oral swabs with rapid molecular diagnostic for pulmonary TB in adults and children - Lancet Global Health, 2024 (systematic review, PMID: 38097297)