Management of a 2-Year-Old with BCG Vaccination Living with Open Pulmonary TB
The child must receive tuberculin skin testing immediately, and if negative, should begin isoniazid preventive therapy regardless of BCG vaccination status, as the primary protection strategy is preventing infection from the infectious household contact. 1
Immediate Actions Required
1. Tuberculin Skin Testing
- Perform tuberculin skin test (Mantoux test with 0.1 mL of 5 TU PPD) immediately 1, 2
- Prior BCG vaccination does NOT contraindicate tuberculin skin testing and should not delay evaluation 1
- A positive tuberculin skin test (≥10 mm induration) in a BCG-vaccinated child who is a TB contact should be interpreted as true M. tuberculosis infection, not vaccine effect 2
2. Preventive Therapy Based on Test Results
If Tuberculin Skin Test is Positive (≥10 mm):
- Initiate isoniazid preventive therapy immediately at 10-15 mg/kg daily (up to 300 mg) for 9 months 3
- Rule out active TB disease before starting preventive therapy 1
- Preventive therapy should be administered to all tuberculin-positive children, even if the date of skin-test conversion cannot be determined 1
If Tuberculin Skin Test is Negative:
- Begin isoniazid preventive therapy immediately (same dosing) 1
- Repeat tuberculin skin test in 8-10 weeks to detect conversion during the window period 1
- Continue preventive therapy throughout this period 1
3. Source Case Management - Critical Priority
The infectious relative must be treated immediately with directly observed therapy (DOT): 1
- Ensure the adult TB patient is on appropriate anti-TB treatment
- Verify treatment adherence through DOT to prevent prolonged infectiousness 1
- Obtain drug susceptibility testing on the adult's TB isolate to guide the child's preventive therapy 3, 4
If the adult fails to cooperate with treatment:
- The child should be removed from contact with the infectious adult until the patient is no longer infectious 1
- This is a public health priority that supersedes other considerations 1
Special Considerations for This Case
Why BCG Does Not Change Management
- BCG vaccination provides >80% protection against severe forms of TB (meningitis, miliary TB) in young children 1, 2, 5
- However, BCG provides uncertain and variable protection against pulmonary TB, especially from household exposure 1, 2
- BCG's protective effect does not eliminate the need for preventive therapy in exposed contacts 1, 2
- The 2-year-old remains at high risk because children <5 years are particularly vulnerable to developing life-threatening TB complications 1
Drug-Resistant TB Considerations
- If the adult relative has isoniazid-resistant TB, use rifampin for preventive therapy instead (dosing per susceptibility results) 1, 4
- If the adult has multidrug-resistant TB (resistant to both isoniazid and rifampin), consult a TB specialist immediately 3
- In cases of MDR-TB exposure where the child cannot be separated, BCG vaccination might be reconsidered if the child has a negative tuberculin test 1
Common Pitfalls to Avoid
Do Not Delay Treatment
- Never delay preventive therapy while waiting for tuberculin skin test results in a household contact 1
- The risk of progression to active TB is highest in the first 2 years after infection, and children <2 years are at particularly high risk for tuberculous meningitis or miliary TB 1
Do Not Assume BCG Provides Adequate Protection
- BCG vaccination status should not influence the decision to provide preventive therapy to exposed contacts 1, 2
- The primary TB control strategy is interrupting transmission, not relying on BCG protection 1
Do Not Ignore the Source Case
- Failure to ensure the adult's treatment adherence is the most common cause of continued transmission 1
- Children with TB almost always acquired infection from infected adults in the same household 1