Tuberculin infection represents the infection with Mycobacterium tuberculosis. This problem may not affect only the possessors of the infection but the people with who they get in contact too. There are known two types of tuberculosis: active and inactive infections. Both of them have to be noticed in time because the people's health is in danger. That is why a tuberculin skin test is recommended.

This test consists of injecting right under the skin a small and precise amount of TB protein (antigens) on the inner forearm. If the person that is having the test was exposed to the TB bacteria his skin will react to the antigens, developing a red bump in the injected area within two days.

One of the most used tests in United States is Mantoux. This test is based on TB antigens called purified protein derivative or PDD. The problem with this test is that it can not say precisely weather it is a active or an inactive infection.

This PDD test uses an exact amount of TB antigens that are injected under the top layer of the skin. It is often used when symptoms are registered and when other testing methods such as a chest X-ray show that the person may have tuberculosis.

Another thing that can not be told after a tuberculin test is the time since the person got infected or if the infection can be passed to other persons.

Even so, a tuberculin test is recommended for persons that get in close contact with someone that has TB, health care workers that are exposed to tuberculosis, people that develop symptoms similar to the TB patients such as ongoing cough, night sweats or weight loss with problematic appetite loss. In need to take this test are also the persons who have abnormal chest X-ray and persons who recently had an organ transplant. Persons with impaired immune systems or those with human immunodeficiency virus (HIV) are at risk for developing tuberculosis.

This tuberculosis skin test is not recommended for persons with known TB infections, positive tuberculin skin tests in the past or skin rashes that might make impossible the interpretation of the test.

Before taking a test you should tell your health care professional if you have TB symptoms or if you had TB in the past, of if risk factors such as contacts with infected persons, a health care worker that may be exposed to people with tuberculosis, occur.

In two or three days after the test the results are available. The size of the bump will determine the result. So, a positive test means a raised bump in the point where the injection was administrated and an induration that is smaller that 2 mm means a negative test.