Annual Screening, Testing, and EducationAnnual TB testing of health care personnel is not recommended unless there is a known exposure or ongoing transmission at a healthcare facility. Health care personnel with untreated latent TB infection should receive an annual TB symptom screen.
This means that being near someone with TB disease when they cough, sneeze, or even talk close to your face for an extended period of time puts you at risk for infection. Kissing, hugging, or shaking hands with a person who has TB doesn't spread the disease.
Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. BCG does not always protect people from getting TB.
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- Bleeding at the injection site (occurring up to 3 days after the skin test)
- blistering, crusting, or scabbing at the injection site.
- deep, dark purple bruise at the injection site (occurring up to 3 days after the skin test)
- difficult or labored breathing.
- hard lump at the injection site.
TB Interferon gamma release assays (IGRAs)The Interferon Gamma Release Assays (IGRAs) are a new type of more accurate test. In this context referring to an assay is simply a way of referring to a test or procedure. IGRAs are blood tests that measure a person's immune response to the bacteria that cause TB.
Results: Among 100 adults who were BCG-vaccinated and had a positive TST result, 30 (30%) had a positive result using QFT-G. Persons from high-incidence countries were 8.2 times more likely to have a positive QFT-G result compared with persons from low-incidence countries (46% versus 9%).
(1) False-positive results may occur in patients with prior infection with M marinum, M szulgai, or M kansasii. Negative: No IFN-gamma response to M tuberculosis antigens was detected. Infection with M tuberculosis is unlikely.
Serial QFT testing of HCWs in North America may result in tremendous over-diagnosis and over-treatment of LTBI, with nearly thirty false-positives for every true infection diagnosed.
The Difference between Latent TB Infection (LTBI) and TB Disease
- a bad cough that lasts 3 weeks or longer.
- pain in the chest.
- coughing up blood or sputum.
- weakness or fatigue.
- weight loss.
- no appetite.
- chills.
- fever.
Screening for latent Mycobacterium tuberculosis infection using tuberculin skin testing followed by interferon-gamma release assays on the day of reading is a reliable approach, as the specificity of QuantiFERON-TB Gold in-tube is not affected by prior tuberculin skin test administration.
They do not help differentiate latent tuberculosis infection (LTBI) from tuberculosis disease. Two IGRAs that have been approved by the U.S. Food and Drug Administration (FDA) are commercially available in the U.S: QuantiFERON®-TB Gold In-Tube test (QFT-GIT); T-SPOT®.
The specificity of QuantiFERON-TB Gold has consistently shown to be >99% in low risk individuals (12). Specificity is the probability that the test indicates a person does not have the disease (or infection) when that person is disease free.
Persons with latent TB infection are not infectious and cannot spread TB infection to others. Overall, without treatment, about 5 to 10% of infected persons will develop TB disease at some time in their lives. About half of those people who develop TB will do so within the first two years of infection.
