Bovine TB Diagnostics.pdf

The scope for existing diagnostic methods to detect infected cattle not currently detected by the existing program in Ireland includes:

The Comparative Intradermal Tuberculin Test (CITT) which is the primary diagnostic test used in Ireland, with two interpretations: standard and severe.
The Single Intradermal Tuberculin Test (SITT) which is used in many countries, but not in Ireland due to non-specific sensitization to bovine tuberculin.
The BOVIGAM® interferon-gamma (IFN-γ) assay, a blood test used as a supplementary test in severely infected herds or groups of animals.

The CITT has a high specificity, but its sensitivity can be affected by various factors, including non-specific sensitization to bovine tuberculin. The SITT has a higher sensitivity, but its specificity is lower due to non-specific reactions.

The use of ancillary tests, such as the IFN-γ assay, can help improve the detection of infected cattle, particularly in severely infected herds. However, the interpretation of these tests requires careful consideration of the test results, animal history, and epidemiological context.

The existing program in Ireland has a number of limitations, including:

The CITT may not detect all infected animals, particularly those with early or mild infections.
The SITT may produce false positive results due to non-specific sensitization.
The IFN-γ assay may not be suitable for use in all situations, such as in herds with low levels of infection.

Overall, the scope for existing diagnostic methods to detect infected cattle not currently detected by the existing program in Ireland is limited by the sensitivity and specificity of the tests, as well as the complexity of the disease and the epidemiological context.