How Do You Tell If a TB Test Is Positive?


Quick Answer

A TB test is positive when a firm red bump develops at the injection site within two days of receiving the TB antigens injection. A positive test result does not determine how long a person has been infected or whether the infection is active or inactive, according to WebMD.

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How Do You Tell If a TB Test Is Positive?
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Full Answer

A TB test involves injecting a small amount of TB antigens, known as purified protein derivative, under the top layer of skin on the forearm and is done to determine whether a person has been exposed to the tuberculosis bacteria. A TB skin test is done when individuals have been in close contact with someone who has TB; for health care workers likely to be exposed; for those who present with symptoms of TB, such as ongoing cough, night sweats and unexplained weight loss; or for those who have had an abnormal chest X-ray, a recent organ transplant or an impaired immune system, states WebMD.

Treatment of tuberculosis involves taking antibiotics for six to nine months, although the exact drugs and length of treatment depend on age, overall health, possible drug resistance, whether the TB is active or latent and the location of infection in the body, according to Mayo Clinic.

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