What are the IDPH (Illinois Department of Public Health) guidelines for a person exposed to active Tuberculosis (TB) in an outpatient setting?

Management of Persons Exposed to Active TB in Outpatient Settings

Persons exposed to active tuberculosis in an outpatient setting should undergo immediate contact investigation with tuberculin skin testing (TST) or interferon-gamma release assay (IGRA) as soon as possible after exposure, followed by repeat testing 8-12 weeks after exposure ends if the initial test is negative. 1

Immediate Actions Following Exposure

Initial Evaluation and Testing

• Baseline testing should be performed immediately unless a negative TST has been documented within the preceding 3 months. 1
• Exposed individuals (except those already known to be positive reactors) should receive a Mantoux tuberculin skin test or IGRA as soon as possible after the exposure is identified. 1
• If the initial test is negative, repeat testing must be performed 8-12 weeks after the exposure ended to detect delayed conversion. 1

Clinical Assessment

• All exposed persons should be evaluated for symptoms suggestive of active TB, including productive cough >3 weeks duration, weight loss, fever, fatigue, night sweats, and anorexia. 1
• Persons with positive test results (≥5 mm induration for high-risk individuals, ≥10 mm for moderate-risk) or symptoms suggestive of TB should receive chest radiographs immediately. 2
• Exposed persons with previously known positive skin tests do not require repeat testing unless they develop symptoms suggestive of tuberculosis. 1

Risk Stratification and Follow-Up

High-Risk Exposed Individuals

• Immunocompromised persons or young children (<5 years) living with or exposed to an infectious TB patient should be considered for temporary relocation until the source patient has negative sputum smears. 1
• Healthcare workers exposed during procedures should be included in employer-sponsored follow-up programs with appropriate screening intervals. 1

Management Based on Test Results

• Positive TST/IGRA with normal chest X-ray and no symptoms: Consider treatment for latent TB infection (LTBI) according to current guidelines. 2
• Positive TST/IGRA with abnormal chest X-ray or symptoms: Obtain three consecutive sputum samples for AFB smear and culture on different days. 3, 2
• Negative initial and follow-up tests: No further action required unless symptoms develop. 1

Outpatient Setting-Specific Protocols

Environmental Controls During Exposure Period

• Exposed individuals who must remain in contact with the infectious patient should be instructed that the patient must cover coughs and sneezes. 1
• If cough-inducing procedures were performed during the exposure, enhanced precautions and closer monitoring are warranted. 1
• Ventilation assessment of the exposure area should be conducted, particularly in clinics serving high-risk populations. 1

Documentation and Reporting

• All exposures must be documented and reported to the local or state health department for contact investigation coordination. 4
• The facility should conduct a risk assessment to determine if the exposure represents evidence of ongoing transmission requiring reclassification of facility risk level. 1

Treatment Considerations for Exposed Individuals

Preventive Therapy Indications

• Exposed individuals with positive TST/IGRA (≥5 mm for high-risk contacts) and no evidence of active disease should be offered preventive therapy. 2
• Preferred regimens include isoniazid with rifapentine for 3 months, or rifampin alone for 4 months. 4
• IGRA-positive individuals benefit more from preventive treatment (RR 3.09 for untreated vs treated) compared to TST-positive individuals (RR 1.11). 5

Monitoring During Follow-Up

• Exposed persons should be reminded to report any pulmonary symptoms promptly during the follow-up period. 1
• Those who decline or cannot complete preventive therapy should be counseled about their risk for developing active TB and instructed to seek evaluation if symptoms develop. 1

Common Pitfalls to Avoid

• Do not rely on a single negative test immediately after exposure—conversion may take 8-12 weeks. 1
• Do not assume BCG vaccination invalidates TST results in exposed individuals—IGRA has better specificity (97.7%) in BCG-vaccinated populations but TST remains acceptable. 6, 5
• Do not delay chest radiography in symptomatic exposed individuals even if TST/IGRA is negative, as both tests have reduced sensitivity in immunocompromised patients. 7, 8
• Failure to include all potentially exposed persons (including service personnel, volunteers, and contract staff) in the contact investigation. 1