Ovine Johne's Disease (OJD) was first detected in sheep in Australia in 1980. Monitoring of sheep for OJD commenced in New South Wales (NSW) abattoirs in late 1999 as part of a national program.

Following the results of research trials in NSW, Gudair® vaccine was approved by the National Registration Authority in April 2002 as an aid to the control of OJD. Previously the vaccine had been limited to use under a special permit restricted to heavily infected flocks (>5% deaths annually).

The wider availability of OJD vaccine changed the emphasis of Property Disease Management Programs from reliance solely on management strategies. Research demonstrating no untoward outcomes following vaccination of adult sheep in a heavily infected flock was pivotal in encouraging many producers to undertake whole of flock vaccination. The major emphasis was, however, on vaccination of lambs at less than 16 weeks of age in infected and at-risk flocks.

From January 2001 to December 2006 6.86 million doses of vaccine were sold in NSW. It is estimated around 70% of replacement sheep were being vaccinated annually in the High Prevalence area and 30% in the Medium Prevalence area.

Field officers report that clinical disease is now rare in vaccinated flocks in the High Prevalence Area previously suffering high death rates. While this is generally attributed to vaccination, the role of better management strategies, including strategic culling of heavily infected mobs or age groups, and environmental factors (including drought) remains unclear.

Abattoir monitoring provides an independent measure of the level of OJD infection present in the sheep population of NSW. This presentation will compare the uptake of vaccine with the prevalence of lesions detected in monitoring of adult sheep for OJD from November 1999 to December 2006, based on the OJD prevalence area and local government area from which the sheep were derived.