Positive BJD result triggers WA crisis meeting

James Nason, 13/03/2013

Efforts to clear six Bovine Johne's Disease-trace properties in Western Australian have been dealt a blow after a bull on one of the properties produced a positive result on an initial PCR test.

Six Kimberley-region properties have been under quarantine restrictions since November last year when BJD was detected on a Central Queensland cattle stud.

The six properties had purchased a combined total of 452 bulls from the stud in the previous 13 years, and have since been mustering to locate the remaining imported bulls, which have in turn been culled and tested.

WA is a BJD-free zone and the industry and state government have a policy of culling any suspect animals to prevent the potential for the wasting disease to spread.

A state-based biosecurity scheme funded via a 20c/head transaction levy paid by producers is used to compensate affected enterprises for losses incurred through mustering, testing and eradication.

The response has so far resulted in 109 of the bulls imported from Queensland being culled and tested. Given that tracings date back to 2000, it is believed a significant number of the 452 imported bulls would have already died through natural attrition or have been processed.

DAFWA this week confirmed that an initial PCR test on one of the bulls imported from the infected Queensland herd has produced a positive result.

The department said a follow-up culture test is underway to further inform the final result, and further testing is also underway on the property to determine if the disease has spread to other animals.

While further tests are required to provide definitive evidence of BJD infection, a positive PCR result is considered of a strong sign that an animal is infected with BJD.

The recently introduced PCR tests directly detects the DNA of BJD bacteria in faeces, and is considered to have the same degree of accuracy as the faecal culture test, but can produce a result within two to three weeks, as opposed to the 8-12 weeks it takes to produce a faecal culture test result.

In Queensland where a major BJD testing and eradication program is underway, the State Government’s high degree of confidence in the accuracy of PCR tests is underscored by its advice that “a positive PCR result indicates that the animal has BJD and is excreting BJD bacteria”.

The WA Pastoralists and Graziers Association has organised a meeting in Broome next Thursday, March 21, to discuss the future management of BJD in the state, and DAFWA representatives will attend.

The ramifications of a potential BJD positive will be high on the agenda.

DAFWA chief veterinary officer Peter Morcombe said a timeframe for conclusive property results cannot yet be provided due to the need for additional testing.

Nor was testing of individual bulls and herds at a point where the definitive disease status of any of the trace properties in WA could be finalised.

Dr Morcombe noted that in a meeting with cattle industry representatives to discuss BJD-trace properties in the Kimberley region last week, industry representatives were supportive of the need to undertake further testing as required and report when conclusive property results were available.

“The priority of both industry and the department is to minimise the impact of the disease while maintaining the economic sustainability of the Kimberley cattle industry.

“The department is working closely with affected pastoralists and the industry on this BJD response.

“We are also working actively with property owners to minimise the impact of movement restrictions”


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