Changes To Inconclusive TB Reactor Testing Policy

The Welsh Government has introduced a change to the Inconclusive Reactor (IR) policy in persistent TB breakdowns (those lasting for 18 months duration or longer). The change came into effect on the 1st January 2020.

Policy Summary

Under the policy, IRs at standard interpretation will be slaughtered with compensation. Severe IRs will be tested with both a parallel Interferon-gamma test (the “gamma test”) and an IDEXX Antibody test (the “antibody test”). Any test positive animals will be slaughtered with compensation. The policy will be in place fully by February 2020.

More Detail

All skin tests in a herd with a TB breakdown exceeding 17 months in duration will be read at severe interpretation. OVs should confirm readings for all severe IRs also at standard interpretation, as standard IRs will be slaughtered. From and including the first Short Interval Test (SIT) after the TB breakdown has been 17 months in duration, all standard IRs will be slaughtered and all severe IRs will usually be sampled for both a gamma test and an antibody test from 10-30 days after TT1 of the skin test, until an exit position is reached.

The existing policy on animals, which are severe IRs at consecutive tests on 2 or 3 occasions, will remain the same as in non-persistent herd breakdowns. APHA case vets may consider removing some of these animals as Dangerous Contacts (DCs), but it is expected that the previous policy of removing all standard and severe IRs will not be adopted for any individual herd.

The exit position is reached at an SIT, when there is a clear testing result, or only severe IRs are identified (no change to existing policy). Action at the exit position – APHA will subject the severe IRs to a gamma test only (no change to existing policy). If all of the IRs at the final clearing test (2nd clear test) have a negative gamma test result, then the test interpretation will revert to standard and movement restrictions will be revoked (no change to existing policy). If any of the severe IRs out of a group of severe IRs are positive to the gamma test, then antibody tests will be carried out on stored serum samples collected at the time of gamma sampling from all severe IRs in the group (10-30 days post TT1). Following a gamma, or antibody test positive result, two clear SITs at severe interpretation are needed, before movement restrictions can be withdrawn (no change to existing policy).

FUW Members seeking clarification on their particular circumstances can contact their local county office for help.