What is the primary TB surveillance test that accredited veterinarians perform for cattle?

The primary tuberculosis (TB) surveillance test that accredited veterinarians perform for cattle is the intradermal caudal fold test. This method involves the intradermal injection of a purified protein derivative (PPD) specific to Mycobacterium bovis, the bacterium that causes bovine TB, into the skin fold located in the caudal (tail) region of the animal.

When the test is administered, the animal's immune system responds to the PPD if it has been exposed to the TB bacteria. After 72 hours, a veterinarian will assess the injection site for swelling or reaction, which indicates a positive response and suggests the presence of an infection.

This testing is crucial in controlling and monitoring the spread of bovine TB, as it allows for early detection of infected animals within herds. It is recognized as the standard method for TB surveillance in cattle, ensuring food safety and protecting public health.

Other options like the ELISA test and blood test may be used for various disease diagnostics, but they are not the primary methods for TB surveillance in cattle. Similarly, "skin reaction test" is a broader term that may refer to multiple types of tests but does not specifically indicate the standardized procedure used for TB diagnosis in cattle