Dr. Damien Barrett:

I will start by discussing the limitations. At best, the skin test has a sensitivity of 80%. We use the test because it has a specificity of over 99%. The test has very few false positives and that is important in a national screening programme. We increase the sensitivity of our programme by using the blood test where we know there is cattle-to-cattle transmission, which raises sensitivity to between 90% and 95%. The inherent problem relates to the skin test and that imperfection.