Normal Values:

If you have a negative test result, the area may be a little red, but it will not be swollen and firm like a mosquito bite. This means you have not been infected with the bacteria that cause tuberculosis.

What abnormal results mean:

If you have been infected with tuberculosis, the area may become red and swell like a mosquito bite in 48 - 72 hours. This is considered a positive test result. It means your body's immune system detected the substance injected under your skin.

A positive TB tine test does not mean that you have active tuberculosis. It only means that you have been exposed and infected at some point in the past.

A chest x-ray may be taken to determine whether you have active tuberculosis.

If you have a positive TB tine test, you should also have a TB skin test.