Tuberculosis (TB) testing determines if a person has been infected with the bacterium Mycobacterium tuberculosis. Screening is often required for employment, travel, or following exposure to someone with active TB disease. The tests do not distinguish between latent TB infection (inactive bacteria) and active TB disease (multiplying bacteria causing illness). Understanding the testing process helps ensure timely results.
Primary Healthcare Provider Settings
The most convenient option for routine testing is often the established Primary Care Physician (PCP) or family doctor’s office. These settings can integrate TB screening into a standard physical or preventive care visit, and testing is usually covered by health insurance. However, scheduling a test through a PCP may require an appointment several days or weeks in advance.
Urgent care centers and retail clinics (such as those located within pharmacies) offer walk-in testing. These locations are useful for individuals needing a test quickly or who cannot get a timely appointment with their regular physician. While many sites primarily offer the skin test, they often feature extended hours and weekend availability. Confirm that the center performs the required test and verify the out-of-pocket cost, as it may be higher than a routine PCP visit.
Public Health and Specialized Testing Locations
Local or county health departments serve as a community resource and frequently offer TB testing at a reduced cost or for free. Focusing on disease prevention and control, they are a reliable location for those without insurance or who are part of a high-risk population. Health departments are also designed to coordinate follow-up care if a positive result occurs, linking the patient to necessary treatment.
Specialized locations serve specific populations. Student health centers on university campuses and occupational health clinics used by employers (especially in healthcare or education) are common examples. Occupational clinics screen new hires and conduct periodic testing as required by policy. Individuals needing tests for international travel or immigration may use travel clinics or public health centers familiar with the required documentation and testing types. These specialized clinics ensure the testing meets specific administrative requirements.
Understanding the Types of TB Tests
The Tuberculin Skin Test (TST), also known as the Mantoux or PPD test, is one of the two main screening methods. This procedure involves injecting a small amount of purified protein derivative (PPD) just under the skin, usually on the forearm. The patient must return to the clinic 48 to 72 hours later to have the injection site visually inspected and measured for a reaction.
The alternative is the TB Blood Test, or Interferon-Gamma Release Assay (IGRA), which includes commercial tests like QuantiFERON-TB Gold Plus. An IGRA requires a single visit for a blood draw, which is sent to a laboratory to measure the immune system’s response to TB-specific proteins. This test is more objective and is the preferred option for individuals who have received the Bacille Calmette-Guérin (BCG) vaccine, as the BCG vaccine can cause a false-positive TST result. The choice between the TST and an IGRA often depends on local availability and individual risk factors.
What to Expect During Testing and Follow-Up
No special preparation is needed before a TB test, and patients can eat or drink normally beforehand. Before administration, confirm with the provider which specific test will be used. Also, verify whether the cost will be covered by insurance or what the out-of-pocket fee will be. This step prevents unexpected bills and ensures the correct test is performed for the screening requirement.
If a TST is performed, patients must return for the reading appointment between 48 and 72 hours later; failure to do so invalidates the test and requires a retest. A positive result from either the TST or IGRA does not mean a person has active, contagious TB disease. Instead, it indicates exposure to the bacteria and necessitates immediate follow-up for further diagnostic evaluations. This evaluation typically involves a chest X-ray to look for signs of active disease in the lungs. A sputum test may also be ordered to check for the presence of the bacteria. If latent TB infection is confirmed, a healthcare provider will recommend a course of antibiotics to prevent the infection from progressing to active disease.