Mantoux test

The Mantoux test is a test developed to detect tuberculosis. In the year 1890, Robert Koch developed tuberculin, as a treatment for tuberculosis. The substance proved ineffective to treat the disease, today it is commonly used to detect it, though. Tuberculin is a substance based on the pathogen that causes tuberculosis. Charles Mantoux, a French physician, developed a test method, based on the work of Koch. 
A positive test result simply says that the immune system came in contact with Mycobacteria - this does not necessarily mean that people with a positive test result have been infected with tuberculosis. Such a result, which shows as positive, even though the outcome should be negative is called "false positive". 
The test shows the reaction of the immune system to tuberculin. This requires an intact immune system: People whose immune system is weakened, for example those with a HIV infection, may also show a "false negative": Their immune system may simply be too weak to react. Similarly, the use of certain substances, such as steroids may lead to false negatives.