Tuberculosis (TB) screening is a standard pre-employment requirement for teachers and other school personnel across the United States. Public health agencies mandate this testing to prevent the spread of Mycobacterium tuberculosis, the bacterium that causes the disease, within educational environments. Screening school staff helps protect vulnerable populations from airborne transmission. Testing procedures and validity duration are governed by state public health laws and local school district policies.
Initial Testing Requirements and Acceptable Methods
Teachers typically undergo one of two medically accepted tests for initial employment screening to detect the presence of TB bacteria. The traditional method is the Tuberculin Skin Test (TST), also known as the purified protein derivative (PPD) test. This procedure involves injecting a small amount of tuberculin under the skin. The individual must return 48 to 72 hours later to have the injection site evaluated for a reaction.
A more modern alternative is the Interferon-Gamma Release Assay (IGRA), such as QuantiFERON-TB Gold Plus or T-SPOT.TB. The IGRA is a blood test measuring the immune system’s response to TB-specific antigens. This method requires only a single visit for a blood draw, eliminating the follow-up reading required by the TST.
IGRA is also the recommended test for individuals who have received the Bacille Calmette-Guérin (BCG) vaccine, as the TST can produce a false-positive result in this group. Both the TST and IGRA are widely accepted for employment clearance in schools. Initial testing is a baseline requirement completed before a teacher begins working. Documentation of the test, including the date and result, is required for the personnel file to prove compliance.
The Duration of TB Test Validity
For the majority of teachers who receive a negative result on their initial pre-employment screening, the test is considered valid indefinitely. Routine retesting is no longer required in many US states, reflecting a shift away from older mandates for annual or biannual screening. The initial negative test establishes a baseline of no infection at the time of hire.
The necessity for repeat testing primarily hinges on an individual’s potential for new exposure or the development of symptoms. A teacher would be required to undergo retesting if they have a known close-contact exposure to an individual with active TB disease or if they travel frequently or reside in a country with a high prevalence of TB. Additionally, if a teacher develops symptoms suggestive of active TB, such as a persistent cough lasting three weeks or longer, unexplained weight loss, or night sweats, a medical evaluation and new test would be necessary.
Policies regarding ongoing surveillance vary significantly at the state and local levels. Some states have replaced periodic testing with a mandatory TB risk assessment completed by a healthcare provider every few years, such as every four years in California. This assessment focuses on identifying new risk factors rather than repeating the test on a fixed schedule. Teachers should refer to their state’s public health code or local school district’s employee health policy to confirm ongoing clearance requirements.
Required Follow-up After a Positive Result
A positive result on an initial TB test indicates the teacher has been infected with the TB bacterium, but it does not confirm active disease. This result signifies Latent TB Infection (LTBI), meaning the bacteria are dormant and the individual is not infectious. The immediate next step is a mandatory medical evaluation to definitively rule out active TB disease, which is the contagious form.
The medical workup typically includes a chest X-ray to check for visible signs of active disease in the lungs. If the chest X-ray is clear and the teacher has no symptoms, they are medically cleared to work, even with confirmed LTBI. If the X-ray is abnormal or if symptoms are present, further diagnostic tests, such as sputum cultures, are required to confirm or exclude active disease.
A diagnosis of active TB disease requires the teacher to begin treatment and be medically cleared before returning to the classroom. A teacher with only LTBI is generally offered preventive treatment to reduce the chance of the latent infection becoming active later. Documentation from a healthcare provider confirming the distinction between latent infection and active disease is essential for satisfying employment requirements and maintaining their clearance.