What is the recommended evaluation and management after a known exposure to active tuberculosis?

Management After Tuberculosis Exposure

After a known TB exposure, immediately perform symptom evaluation and tuberculin skin test (TST) or interferon-gamma release assay (IGRA), then repeat testing 8-10 weeks after the last exposure if the initial test is negative. 1, 2

Immediate Actions Upon Recognition of Exposure

Step 1: Identify All Exposed Individuals

• Interview the source patient and review medical records to determine all locations visited before isolation (outpatient clinics, hospital rooms, radiology areas, patient lounges) 3
• Identify all potentially exposed persons including direct caregivers, therapists, clerks, transportation personnel, housekeepers, and social workers 3
• Notify the public health department immediately to coordinate community contact investigation 3

Step 2: Prioritize Testing Based on Exposure Intensity

• Test the most intensely exposed individuals first (those with closest, most prolonged contact with the source patient) 3
• If transmission occurred to this high-intensity group, expand testing to those with less intense contact 3

Testing Protocol

Initial Testing (At Time of Exposure Recognition)

• Perform symptom evaluation immediately, assessing for cough, fever, night sweats, weight loss, and hemoptysis 1, 2
• Administer TST or IGRA as soon as possible after exposure is identified 3, 1
• Critical caveat: A negative test during the first 8 weeks post-exposure does NOT rule out infection due to the immunologic window period 2

Follow-Up Testing (8-10 Weeks Post-Exposure)

• Repeat TST or IGRA 8-10 weeks after the last exposure using the same test type as the initial test 1, 2
• This timing corresponds to the period required for the immune system to mount a detectable response to M. tuberculosis 2
• A positive result on this second test indicates infection occurred during the exposure period and warrants treatment for latent TB infection 2

Evaluation of Positive Tests

• All persons with newly positive TST/IGRA or test conversions require prompt evaluation for active TB including thorough history, physical examination, and chest radiograph 3
• If chest radiograph or clinical findings suggest active TB, obtain sputum for acid-fast bacillus smear and culture 3
• Obtain drug-susceptibility pattern of M. tuberculosis from the source patient to guide appropriate preventive or curative therapy 3

Special Populations Requiring Immediate Prophylaxis

Children Under 5 Years

• Begin treatment for presumptive infection (window prophylaxis) immediately after excluding active disease, even with negative initial testing 2
• This population is at high risk for severe disseminated TB and TB meningitis 2

HIV-Infected and Immunocompromised Contacts

• Provide immediate prophylactic treatment after active disease is excluded, regardless of initial test results 2
• These individuals cannot wait for the 8-10 week repeat testing window 2

Management Based on Test Results

For Persons with Test Conversion or Positive Results

• Initiate treatment for latent TB infection unless medically contraindicated 1
• Preferred regimens include: 1
  • Isoniazid plus rifapentine once weekly for 3 months
  • Isoniazid plus rifampin daily for 3-4 months
  • Rifampin alone daily for 4 months
  • Isoniazid alone for 9 months

For Persons with Previously Documented LTBI or TB Disease

• Do not repeat TST or IGRA after exposure 1, 2
• Instead, perform clinical evaluation only if TB disease is suspected based on symptoms 1

For Persons Who Remain Test-Negative After 8-10 Week Repeat

• No further testing or treatment required if asymptomatic 3
• Counsel about TB symptoms and need for prompt evaluation if symptoms develop 3

Critical Pitfalls to Avoid

• Never assume a negative test during the first 8 weeks post-exposure rules out infection—this is the most critical error in TB contact management 2
• Do not delay prophylactic treatment in high-risk contacts (especially young children and immunocompromised individuals) while waiting for repeat testing 2
• Persons with latent TB infection who cannot or will not complete preventive therapy should not be excluded from work but must be counseled about risk of developing active TB and instructed to seek prompt evaluation for any TB symptoms 3

Ongoing Surveillance

• If additional test conversions are detected during follow-up, reassess possible reasons for ongoing transmission and implement corrective interventions 3
• Continue repeat testing every 3 months until no new conversions are detected 3
• If conversions persist after two rounds of follow-up testing, implement high-risk protocol and consult public health department or TB experts 3