DAFF Information Seminar on Bovine Tuberculosis. Dublin, 9-10 October, 2007
Aspects of the ERAD Approach to the Eradication of Tuberculosis in Cattle
John D. Collins

The logic for the control and elimination of Mycobacterium bovis from the national herd lies in
its infectivity for animals and humans, the disruption it causes in livestock production and its
impact on international trade in live cattle and in beef and dairy products.

The earlier extensive debate on different aspects of the programme was itself an impediment to
eradication as it distracted attention from the real goal, that is, the eradication of this infectious
disease.

The establishment of ERAD was an acknowledgment of the advantage to be gained from the
direct involvement of all stakeholders in the acceleration of the eradication programme.

At national level, an ongoing detailed scientific assessment of the prevailing situation provides
direction as to how best to accelerate eradication, by the use both of incentives and controls.

Nationally, analysis of changes in the tuberculosis status of herds rather than the numbers of
reactors identified, is the preferred indicator of progress in eradication.

Risk assessments, at herd level, based on the number of standard tuberculin reactors and the
number of such reactors with tuberculous lesions at slaughter disclosed in herds over the period
of the restriction, i.e. a restriction episode analysis, provide a truer picture of the current
situation.

A more formal approach to risk assessment, as was initiated by ERAD, now takes into account
the extent, distribution and nature of herd breakdowns and provides epidemiological input into
policy formulation.

Active surveillance of clear herds allows these herds to retain their status as free to trade.

Significant improvements in the control of tuberculosis in Irish cattle herds have followed both
reactive and proactive badger removal.

The effectiveness of tuberculin testing, as a component of the eradication programme, is to a
considerable extent determined by the strategy employed in the use of the test.

The interferon-γ assay, when used strategically in the management of herds undergoing active
infection, contributes to the early control of the disease.

The inclusion of the number of reactors in herds already under control in the overall number of
reactors disclosed nationally over a period overstates the true prevalence of tuberculosis in the
national herd.

Eradication of tuberculosis in cattle is achievable with the resources currently available
provided the integrity of the farm as the primary epidemiological unit is maintained. This
places a considerable responsibility on the herdowner, as a stakeholder in the overall
programme.