Tuberculosis Screening

Tuberculosis (TB) screening is a process used to identify individuals who have been infected with Mycobacterium tuberculosis, the bacteria that causes TB. The goal of TB screening is to detect the disease early, before symptoms appear, and to prevent its spread to others.

Types of TB Screening Tests

• Mantoux Tuberculin Skin Test (TST): This is the most commonly used test for TB screening. It involves injecting a small amount of tuberculin into the skin, and after 48-72 hours, the skin is checked for induration (swelling). A positive reaction indicates that the individual has been exposed to TB.
• Interferon-Gamma Release Assay (IGRA): This is a blood test that measures the immune response to TB. It is used to detect latent TB infection and is often used in conjunction with the TST.
• Chest X-ray: A chest X-ray may be used to diagnose active TB disease, especially in individuals who have symptoms such as coughing or chest pain.
• Sputum Smear Microscopy: This test involves collecting a sample of sputum (mucus) from the lungs and examining it under a microscope for the presence of TB bacteria.

Who Should Be Screened for TB?

The following individuals should be screened for TB:

• People who have been in close contact with someone who has active TB disease
• Individuals who have recently immigrated from countries where TB is common
• Healthcare workers who are at risk of exposure to TB
• People who live or work in high-risk settings, such as homeless shelters or prisons
• Individuals with certain medical conditions, such as HIV/AIDS or diabetes, that increase their risk of developing active TB disease

What to Expect During TB Screening

The TB screening process typically involves the following steps:

• A healthcare provider will review the individual's medical history and perform a physical examination
• A TST or IGRA test may be administered, depending on the individual's risk factors and medical history
• A chest X-ray may be ordered if symptoms are present or if the TST or IGRA test is positive
• Sputum smear microscopy may be performed if active TB disease is suspected

Interpretation of TB Screening Results

The results of TB screening tests are interpreted as follows:

• A positive TST or IGRA test indicates that the individual has been exposed to TB and may have latent TB infection
• A negative TST or IGRA test does not necessarily rule out TB, especially in individuals who have weakened immune systems
• A chest X-ray that shows signs of TB disease, such as lung lesions or cavities, indicates active TB disease
• A sputum smear microscopy test that is positive for TB bacteria confirms the diagnosis of active TB disease

Follow-up Care After TB Screening

Individuals who have a positive TB screening test result should receive follow-up care, which may include:

• Further testing to confirm the diagnosis and determine the extent of the disease
• Treatment with antibiotics to prevent the development of active TB disease (for individuals with latent TB infection)
• Treatment with a combination of antibiotics to cure active TB disease
• Regular monitoring to ensure that the individual is responding to treatment and to detect any potential side effects