OJD Prevalence Areas in Australia
What are the prevalence areas?
"Prevalence Areas" are regions defined by the proportion of flocks in the region that are estimated to be infected with OJD, based on the results of ongoing abattoir surveillance.
Prevalence Areas, which form a key component of the Assurance Based Credit Scheme, have been defined using the abattoir surveillance data collected by each state and published in surveillance reports over a number of years. Each point allocated under the ABC Scheme represents a fourfold decrease in likelihood of infection being acquired from that particular line of sheep, that means the more points a line of sheep has, the lower the risk they represent.
With the changes that were implemented in March 2008 there are only three OJD Prevalence Areas in Australia. These are:
- Low Prevalence Area (LPA)
- Medium Prevalence Area (MPA)
- High Prevalence Area (HPA)
Monitoring of sheep for OJD and other endemic conditions is continuing nationally with AQIS meat inspectors collecting the data. In line with nationally agreed protocols, the surveillance data is analysed annually to provide additional information on area prevalence.
To claim a particular Prevalence Area status, a jurisdiction has to consistently demonstrate that the flock prevalence is below the maximum cut off for that Prevalence Area at the 95% confidence limit for two consecutive years. If it exceeds the cut-off for two consecutive years, its status may be downgraded. View the current cut off limits.
Several regions in Australia exceeded the agreed limits in 2008 and 2009 so Sheepmeat Council of Australia (SCA) and WoolProducers Australia (WPA); have asked Animal Health Committee (AHC) to amend the prevalence area status or boundaries for these regions, to ensure area prevalence reflects the true risk associated with buying sheep from those regions.
The regions under review are:
Western Australia, currently a Low Prevalence Area
NSW’s Low and Medium Prevalence Areas
Victoria’s Low and Medium Prevalence Areas.
The recent prevalence estimates are included below. Those regions under review are highlighted red. Producers should be aware that if purchasing unvaccinated Nil Assurance sheep from these prevalence areas, there is a high probability that at least some of the sheep may be infected with ovine Johne’s disease.
Estimated flock prevalence of OJD in 2008 and 2009 (95th percentile estimate).
| State | PA | 2008 | 2009 |
|---|---|---|---|
| NSW | High | 95.6 | 70.7 |
| Med | 39.8 | 42.7 | |
| Low | 1.3 | 1.4 | |
| QLD | Low | 0.7 | 0.7 |
| SA | Med | 4.4 | 5.2 |
| Low | 0.3 | 0.5 | |
| TAS | Med | 3.4 | 4.2 |
| VIC | Med | 17.1 | 32.3 |
| Low | 1.9 | 5.3 | |
| WA | Low | 1.7 | 1.6 |
| Eastern states combined | Low | 2.1 | 2.9 |
NOTE: The cut-offs of estimated prevalence for an LPA is 0.8% and for an MPA is 12.5%.
SCA and WPA have advised that there will be no change to prevalence areas while the matter is under consideration, and that no change is anticipated before 1 September 2010.
You can view maps of the current OJD Prevalence areas area here:
OJD Prevalence Area Map - Australia (663 KB)
OJD Prevalence Area Map - NSW (698 KB)
OJD Prevalence Area Map - VIC (708 KB)
Currently there are no Free Zones for OJD in Australia.
For more information on OJD Prevalence Areas contact your State Coordinator.
Page Updated: 9 July 2010