Final answer:
The Single ID comparative cervical tuberculin test (SICCT) is a skin test used to diagnose tuberculosis in animals by checking for an immune response to injected tuberculin. The human equivalent, the Mantoux tuberculin skin test, can yield false-positive results if the person has received the BCG vaccine.
Step-by-step explanation:
The Single ID comparative cervical tuberculin test (SICCT) is a skin test used for detecting tuberculosis (TB) in animals, especially cattle. This test involves injecting tuberculin into the skin and observing the injection site after a few days for signs of an immune response. A positive reaction, indicated by a raised red area that is hard to the touch, or induration, signifies that the animal has been exposed to TB and has a cellular immune response to the bacteria. In humans, a similar test known as the Mantoux tuberculin skin test is used to screen for TB. However, its accuracy can be affected if a person has been vaccinated with the bacillus Calmette-Guérin (BCG) vaccine, as this can cause false-positive results. The tuberculin test falls into the category of delayed hypersensitivity reactions, which are mediated by memory T cells that could have been created during an active infection or from past exposure.