Always ask the 3 Questions, and consider testing:
- Were you born or have spent time in a high-endemic country for TB?
- Immunosuppression? (Current or planned)
- Previous close contact to a person with TB disease?
- Person traveling in TB endemic areas.
- Migrant workers.
- Person experiencing homelessness.
- Contact to a tuberculosis case.
- Foreign-born person from tuberculosis-endemic area.
- Person who injects drugs.
- Immunosupressed person (e.g., HIV positive or organ transplant).
- Resident/employee of healthcare, correctional or long-term care facility.
- Person with chronic medical problem (e.g., diabetes, end stage renal disease).
When to test
In addition to the considerations above, testing should occur when a patient fits the criteria while screening. Testing is required for:
- Healthcare workers or healthcare students.*
- Residents of long-term care nursing facilities.*
- People who inject drugs.
*Two-step testing is required for healthcare workers at entry and people admitted to nursing homes.
Tuberculosis Skin Test (TST):
- Mantoux test with Tubersol or Aplisol PPD solution.
- Remember to date the vial and discard 30 days after opening.
Interferon Gamma Release Assay:
- Blood testing for TB infection with a QuantiFeron-TB Gold Plus® (QFT).
- QFT is preferred by the CDC for screening those with a history of BCG vaccine
- Children under 2 should be screened using a skin test regardless of BCG status
- Check out our guide on How to Recognize BCG Scars from Smallpox Scars.
- QFT is available at most laboratories.
Before screening, have those to be tested complete the Whatcom County Health Department Screening Questionnaire and Consent for Tuberculosis Skin Test form. It lists the specific medical conditions and social risk factors necessary to know in order to correctly interpret TST results.
Documentation is required
Per Centers for Disease Control and Prevention, a verbal report of a positive skin test is unacceptable. There must be written documentation.
- If no documentation is available, a skin test should be applied and read. If it is positive, a chest x-ray should be ordered.
- A TST “converter” is a person who has an increase in reaction size of ≥10 mm within a period of two years.