Final answer:
The Mantoux tuberculin skin test detects TB exposure through skin reactions; however, the BCG vaccine can cause false-positive results since it sensitizes the immune system to tuberculin.
Step-by-step explanation:
Tuberculin Skin Test and BCG Vaccine:
The tuberculin skin test is a diagnostic tool used to detect exposure to tuberculosis (TB). Tuberculin, a protein extract from TB bacteria, is introduced into the skin via the Mantoux test, and a positive reaction includes swelling and redness, indicating exposure to the bacteria.
However, this test can produce false-positive results in individuals vaccinated with the BCG vaccine, which is common in countries with high TB prevalence. This is because the vaccine primes the immune system to react to tuberculin as if there has been an exposure to TB. Therefore, in these countries, additional tests, such as chest radiographs, may be necessary to confirm a true TB infection.