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The results of this test must be interpreted carefully. The person's medical risk factors determine at which increment (5 mm, 10 mm, or 15 mm) of induration the result is considered positive. [12] A positive result indicates TB exposure. 5 mm or more is positive in An HIV-positive person; Persons with recent contacts with a TB patient
An induration (palpable raised hardened area of skin) of more than 5–15 mm (depending upon the person's risk factors) to 10 Mantoux units is considered a positive result, indicating TB infection. [citation needed] 5 mm or more is positive in HIV-positive person; Recent contacts of TB case
The equivalent Mantoux test positive levels done with 10 TU (0.1 mL 100 TU/mL, 1:1000) are 0–4 mm induration (Heaf 0-1) 5–14 mm induration (Heaf 2) >15 mm induration (Heaf 3-4) The Mantoux test is preferred in the United States for the diagnosis of tuberculosis; multiple puncture tests, such as the Heaf test and Tine test, are not recommended.
The test is then read 48 to 72 hours later by measuring the size of the largest papule or induration. Indications are usually classified as positive, negative, or doubtful. [2] Because it is not possible to control precisely the amount of tuberculin used in the tine test, a positive test should be verified using the Mantoux test. [3]
A Mantoux tuberculin skin test. The Mantoux tuberculin skin test is often used to screen people at high risk for TB. [100] Those who have been previously immunized with the Bacille Calmette-Guerin vaccine may have a false-positive test result. [107]
Negative reaction to tuberculin skin test 2: TB infection No disease: Positive reaction to tuberculin skin test Negative bacteriologic studies (if done) No clinical, bacteriologic, or radiographic evidence of TB 3: TB, clinically active: M. tuberculosis cultured (if done) Clinical, bacteriologic, or radiographic evidence of current disease 4: TB
While most people will clear the virus and get a negative antigen test result within 10 days, some people may keep testing positive for longer than that, experts tell TODAY.com.
The former test quantitates the amount of IFN-γ produced in response to the ESAT-6 and CFP-10 antigens from Mycobacterium tuberculosis, which are distinguishable from those present in BCG and most other non-tuberculous mycobacteria. The latter test determines the total number of individual effector T cells expressing IFN-γ. [citation needed]