Which test is commonly used for annual screening of TB infection?

Which test is commonly used for annual screening of TB infection?

• A. Positive PPD test
• B. Chest X-ray
• C. Blood glucose test
• D. MRI of chest

Answer: (A)

Screening for TB infection focuses on finding latent infection before it progresses. The tuberculin skin test, known as the PPD test, is the classic method used for annual screening because it is inexpensive, widely available, and can be read with a single follow-up visit. It works by injecting a small amount of tuberculin under the skin and checking for an induration after 48 to 72 hours; a positive reaction suggests TB infection (or prior vaccination), but does not by itself prove active disease. If the test is positive, further evaluation, including a chest X-ray, is done to assess for active TB. The other options aren’t used for TB infection screening: a blood glucose test is unrelated, and MRI of the chest isn’t a standard screening tool for TB.

Screening for TB infection focuses on finding latent infection before it progresses. The tuberculin skin test, known as the PPD test, is the classic method used for annual screening because it is inexpensive, widely available, and can be read with a single follow-up visit. It works by injecting a small amount of tuberculin under the skin and checking for an induration after 48 to 72 hours; a positive reaction suggests TB infection (or prior vaccination), but does not by itself prove active disease. If the test is positive, further evaluation, including a chest X-ray, is done to assess for active TB. The other options aren’t used for TB infection screening: a blood glucose test is unrelated, and MRI of the chest isn’t a standard screening tool for TB.