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1. OTFW, what’s happening?

As of 17th January 2022, all new TB breakdowns across Wales, with only two exceptions listed below, will be classified as Officially TB Free Status Withdrawn (OTFW).

2. Why is this change being introduced?

The aims of the proposed change are to increase the likelihood of identifying truly infected animals and to ensure test interpretation leads to simplified messaging and communication of the policy.

3. What about the current OTFS herds?

OTFS herds where the breakdown started prior to 17th January 2022 will remain OTFS unless any further skin test reactor is disclosed, or epidemiological risk factors apply.

APHA also have discretion to convert any OTFS breakdown herd to OTFW, subject to Veterinary Lead Wales’ discretion.

4. What are the exceptions?

The only two exceptions, which will continue to be classified as OTFS, are:

  • OTFS herds where one or more suspect slaughterhouse case(s) have been disclosed and culture results are still pending.
  • Breakdown herds where non-homebred animals positive to Interferon-gamma and/or IDEXX antibody testing only (i.e. no skin reactors) have been disclosed and disease has not been confirmed on PME/culture results.

For these two exceptions, the OTFS herd will become OTFW if:

  • one or more skin test reactors are disclosed in any subsequent test, usually Short Interval (SI) or Check Tests (CT);
  • slaughterhouse cases are culture positive;
  • visible lesions are found at PME and/or culture results are positive for breakdowns where non-homebred animals are Interferon-gamma and/or IDEXX positive only.

All breakdowns are to be managed the same, meaning no TB breakdowns will be managed as Officially TB Free Suspended (OTFS), unless they are as a result of a slaughterhouse case, or blood test positive result (N.Wales additional surveillance).

Testing

5. How will the testing work?

OTFW breakdowns require the first SIT to be interpreted at severe and, if clear, the second at standard to severe.

On the disclosure of a reactor at standard interpretation, the test will be immediately re-interpreted at severe by the OV.

6. How does an OTFW herd regain its OTF status?

OTFW breakdowns require two clear Short Interval Tests (SIT) to regain OTF status.

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