Which of the following is NOT a type of Tb testing?

The correct answer is the blood transfusion test, as it is not considered a type of tuberculosis (Tb) testing. Tuberculosis testing is aimed at identifying individuals who may have been infected with the Mycobacterium tuberculosis bacteria.

The caudal fold test, gamma interferon test, and comparative cervical tuberculin test are all established methods for Tb testing. The caudal fold test is commonly used in veterinary medicine for diagnosing Tb in animals, while the gamma interferon test is a type of blood test that measures the immune response to specific Tb antigens. The comparative cervical tuberculin test is another method used primarily in animals, which involves testing for hypersensitivity reactions to tuberculin.

In contrast, a blood transfusion test does not relate to diagnosing or screening for Td. Therefore, identifying individuals who may have active or latent tuberculosis cannot be achieved through a blood transfusion test.