What is the recommended tuberculosis chemoprophylaxis regimen (including dosing, duration, alternatives, monitoring, and HIV considerations) for a child who is a close contact of an infectious TB case without active disease?

Tuberculosis Prophylaxis in Pediatric Contacts

For children who are close contacts of infectious TB cases without active disease, give isoniazid 10–15 mg/kg daily (maximum 300 mg) for 6 months, or alternatively rifampicin plus isoniazid for 3 months, after excluding active TB with chest radiography and clinical assessment. 1

Initial Assessment Algorithm

Step 1: Exclude Active Disease

• Obtain a chest radiograph on all child contacts regardless of age or tuberculin skin test (TST) status 1
• If the chest radiograph shows any abnormality, this is active TB disease requiring full 4-drug treatment (isoniazid, rifampicin, pyrazinamide, ethambutol) for 6 months, not prophylaxis 2
• Assess for clinical symptoms: fever, cough >2 weeks, weight loss, night sweats, lymphadenopathy 1

Step 2: Perform Tuberculin Skin Testing

• Use Heaf test or Mantoux (10 TU) at initial contact 1
• Mantoux interpretation: ≥5 mm induration = positive (Heaf 2), ≥15 mm = strongly positive (Heaf 3–4) 1

Prophylaxis Regimens by BCG Status

Children WITHOUT Prior BCG Vaccination

• Start chemoprophylaxis immediately regardless of initial TST result 1
• If initial TST is negative (Heaf 0–1): repeat TST at 6 weeks 1
  • If repeat TST remains negative and chest radiograph normal: stop prophylaxis and give BCG vaccination 1
  • If repeat TST converts to positive (Heaf 2–4): complete full 6 months of prophylaxis 1
• If initial TST is positive (Heaf 2–4): give full 6-month prophylaxis course 1

Children WITH Prior BCG Vaccination

• If initial TST is strongly positive (Heaf 3–4): give full chemoprophylaxis immediately 1
• If initial TST is Heaf 0–2 (consistent with BCG scar): repeat TST at 6 weeks 1
  • If repeat TST becomes positive (Heaf 3–4) with normal chest radiograph: give full chemoprophylaxis 1
  • If repeat TST becomes positive with abnormal chest radiograph: give full chemotherapy for active disease 1
  • If no change in TST and chest radiograph normal: no further action required 1

Recommended Prophylaxis Regimens

Primary Regimen

• Isoniazid monotherapy: 10–15 mg/kg daily (maximum 300 mg) for 6 months 1
• This is the most extensively studied regimen with proven efficacy 1

Alternative Regimen

• Rifampicin 10–20 mg/kg daily (maximum 600 mg) plus isoniazid 10–15 mg/kg daily (maximum 300 mg) for 3 months 1
• This shorter regimen offers comparable efficacy with potentially better adherence 3

Special Population: Neonates

Infants Born to Mothers with Smear-Positive Pulmonary TB

• Start isoniazid prophylaxis immediately at 10–15 mg/kg daily for 3 months 1, 3
• Perform TST at 3 months 1, 3
  • If TST negative and mother no longer infectious: stop prophylaxis and give BCG 1, 3
  • If TST positive without evidence of disease: continue isoniazid to total of 6 months 1, 3
  • If evidence of disease (clinical signs or abnormal chest radiograph): give full chemotherapy 1, 3

Infants Born to Mothers Who Completed TB Treatment

• If mother is confirmed non-infectious (completed treatment, no longer smear-positive): no prophylaxis needed, give BCG vaccination only 3
• Do not reflexively start prophylaxis based solely on maternal TB history; assess current infectiousness first 3

HIV-Infected Children

• HIV-infected children who are close contacts of infectious TB should receive prophylaxis regardless of TST results after active TB is excluded 1
• Test with TST initially; if negative, re-evaluate 3 months after contact discontinuation to determine whether prophylaxis should continue 1
• All infants born to HIV-infected mothers should have TST at 9–12 months of age 1
• Children exposed to active TB should receive prophylaxis after active disease is excluded 1

Monitoring and Adjunctive Therapy

Pyridoxine Supplementation

• Add pyridoxine (vitamin B6) supplementation for children with nutritional deficiencies or who are breastfeeding to prevent isoniazid-induced peripheral neuropathy 1, 4
• Standard pediatric dose: 10–25 mg daily during isoniazid therapy 4

Directly Observed Therapy (DOT)

• All children on TB prophylaxis should receive DOT, with medication administration observed by a healthcare professional or trained observer—not by parents 2
• This is critical for ensuring adherence and preventing treatment failure 2

Clinical Monitoring

• Monthly clinical assessments to evaluate adherence, adverse effects, and symptom development 2
• Monitor for hepatotoxicity: obtain baseline liver function tests in children with pre-existing liver disease 1
• Assess for peripheral neuropathy symptoms (numbness, tingling, weakness) 4

Drug Resistance Considerations

• If the source case has isoniazid-resistant TB, use rifampicin alone for 4–6 months instead of standard prophylaxis 3
• Drug susceptibility testing of the source case is essential to guide prophylaxis regimen selection 2, 3
• Do not use rifampicin-isoniazid combination if rifamycin resistance is suspected 5

Critical Pitfalls to Avoid

• Do not treat radiographic abnormalities as latent infection; any chest X-ray abnormality mandates full disease treatment with 4 drugs 2
• Do not delay prophylaxis while awaiting TST results if the source case is known to be infectious 3
• Do not give BCG vaccination before completing the 3-month assessment in exposed infants, as this complicates subsequent TST interpretation 3
• Do not use 3-month rifampicin-isoniazid regimen for active disease; this is appropriate only for latent infection with normal chest radiograph 2
• Do not use isoniazid monotherapy for active disease; this is inadequate and increases drug resistance risk 2
• Do not rely on parents for DOT; observation must be by qualified healthcare personnel 2
• Do not use once-weekly rifapentine-isoniazid regimens in HIV-infected patients with active pulmonary TB due to higher failure and relapse rates 5

Age-Specific Risk Considerations

• Children <4 years are at highest risk for disseminated TB, including life-threatening meningeal disease, making early prophylaxis initiation critical 3
• Infants and young children have faster progression from infection to disease (weeks to months vs. years in adults) 3
• The risk of TB disease is approximately 60% lower with 6 months of isoniazid prophylaxis 6, 7

Implementation Challenges

• Adherence to prophylaxis is often poor in real-world settings, with completion rates ranging from 12–64% in various studies 6, 8, 9
• The main barrier is parental perception that drugs are unnecessary when the child appears healthy 8
• Educational interventions, SMS reminders, and motivational support may improve completion rates 10
• Health facility factors (caseload, treatment success rates) influence IPT initiation and completion 9