For bovine tuberculosis testing, what is the expected response rate for a comparative cervical test (CFT)?

The expected response rate for a comparative cervical test (CFT) in bovine tuberculosis testing is indeed within the range of 1-5%. This test is designed to assess the immune response of cattle to mycobacterial antigens, particularly in detecting latent infections of Mycobacterium bovis, the causative agent of bovine tuberculosis.

In practice, the CFT involves comparing the results of skin reactions to two different antigens. A significant response indicates exposure to the pathogen. The testing method is highly sensitive but the response rate can vary depending on factors such as the population being tested, the severity of the infection, and the timing of the test. The expected 1-5% response rate reflects the fact that while the test is reliable, not all animals exposed to the pathogen will demonstrate a visible response due to varying immune responses. This range takes into account that some animals may have a strong immune reaction, while others, particularly those with a latent infection, may not respond as robustly.

Understanding this rate is vital for interpreting testing results in the context of herd health management and control of bovine tuberculosis.