What is the primary TB surveillance test performed by accredited veterinarians for cattle?

The primary tuberculosis surveillance test performed by accredited veterinarians for cattle is the intradermal caudal fold test. This method involves injecting a small amount of tuberculin purified protein derivative (PPD) into the skin of the caudal fold (the area at the base of the tail) of the cattle. The test is designed to elicit a delayed hypersensitivity reaction in animals that have been exposed to the Mycobacterium bovis, the bacterium that causes bovine TB.

A positive reaction typically indicates that the animal has been infected with the bacteria, thus identifying potential carriers of the disease within a herd. This is critically important for controlling the spread of bovine tuberculosis, as it allows for the early detection and management of infected animals. The intradermal caudal fold test is widely recognized and utilized as the standard diagnostic tool in many countries, highlighting its reliability and effectiveness in veterinary health assessments related to tuberculosis in cattle.

Other methods mentioned, such as blood tests or skin prick tests, are not the primary means of screening for bovine TB. X-ray examinations can provide additional insights into lung pathology, but they are not standard for TB surveillance in cattle.