THE presence of virulent footrot has fallen significantly in WA since 2004, according to the Agriculture Department.
The department's footrot eradication manager, Tony Higgs, said the eradication program in WA had been progressing well, with producers becoming more aware of biosecurity measures.
Mr Higgs said the number of properties quarantined for footrot had fallen to 49 properties as at June 30, with 133,000 sheep.
This compared to 77 properties quarantined for the same period in 2004 and 91 quarantines in 2003.
He said the decline in the number of quarantines could be attributed to an increased effort on infected properties, but probably of more significance was the higher level of surveillance in 2003-04.
Extra funding from Australian Wool Innovations Limited (AWI) in 2003-04 had enabled an increase in surveillance.
"Surveillance at abattoirs has again proven to be a highly efficient and effective means of detecting virulent footrot," Mr Higgs said.
"Higher surveillance activity has helped to identify infected properties before there is a chance for the disease to spread to other flocks.
"This is the seventh consecutive year where abattoir surveillance has been used with more lines of sheep inspected this year than in any other year."
Mr Higgs said more than 2900 lines of sheep were inspected in 2004-05 with only four new virulent footrot cases (0.14pc) found.
In 1998-99 there were 30 new cases identified from 660 lines (4.5pc).
"The reduction in the percentage of new cases being identified through the abattoir is another encouraging measure of progress with eradication," Mr Higgs said.
The other key surveillance tool being used was DNA fingerprinting of the bacteria that caused the disease.
"Knowing the DNA fingerprint of the bacteria assists with tracing the spread of the disease from farm to farm," Mr Higgs said.
"Being able to explain the way the disease has spread helps ensure that each outbreak is contained.
"DNA fingerprinting can also be used as another tool to measure progress with eradication by monitoring changes in the number of different types of bacteria remaining in WA."
Mr Higgs said there was not enough data to assess progress of footrot eradication by this means.
He did not think the new gene marker for footrot that had been identified in New Zealand would be prevalent in Australia.
"In New Zealand the prevalence for footrot is recorded at 50pc of properties," Mr Higgs said.
"New Zealand has no control program whereas in Australia 95.5pc of properties don't have footrot.
"I find it hard to see Australian sheep breeders using genetic resistance to footrot.
"If Australia was not working on a total eradication program of footrot in Australia and let footrot go, then maybe there would be justification for breeding towards a genetic resistance."
Mr Higgs said the target for eradication of virulent footrot from WA was 2014.
"The way things are tracking we should achieve this aim," Mr Higgs said.
"A continued focus on maintaining highly effective surveillance system, both at abattoirs and on farms is essential for meeting this aim."
Mr Higgs said sheep owners played an important role in this by reporting any suspicious signs of footrot as soon as possible.
"The sooner that an outbreak is detected the lower the risk that the disease will spread to other sheep on the farm and on to other farms," he said.
"Any signs of footrot should be reported immediately for further investigation by the department."