Testing identifies two new possible BJD detections

James Nason, 09/01/2013

Preliminary test results on trace-forward animals in Queensland have indicated that a single animal on each of two properties may have been infected with Bovine Johne’s Disease.

Queensland Chief Veterinary Officer Rick Symons said the emergence of possible new detections was not an unexpected result and it was likely that some positive cases would be found throughout the process.

The animals came from the original infected property near Rockhampton, where the detection of three BJD infected cattle triggered a quarantine and testing program which initially involved more than 170 properties in Queensland, the Northern Territory and Western Australia,

The animals were not showing clinical signs, but histology tests, where tissue is examined under a microscope, showed the likely presence of BJD.

However, according to the Queensland Department of Agriculture, when histology is undertaken, there is a possibility of a false positive result because the histology method detects mycobacteria by staining, and there are also other types of mycobacteria aside from Johne’s disease.

“As such, while this result is suggestive of BJD, tissue culture must be undertaken to achieve a definitive result,” Dr Symons said.

“The timing of results from this process depends on the disease status. If negative, the results may not be available until March 2013.

“The testing will also show whether the animals were shedding bacteria, which will help us understand the risk of infection to other animals on the property.”

Faecal samples from the two animals are being sent to a New South Wales laboratory for additional testing using the new PCR test that has been developed. Like faecal culture, the PCR test can only detect the bacteria of an infected animal if it is shed in its faeces at the time samples are collected.

As such, if a positive is received using the PCR test, the result is definitive. However, a negative result is not definitive and needs to be confirmed by tissue culture.

“This result confirms that the incident response process being undertaken by Biosecurity Queensland is on track. Biosecurity Queensland is assessing animals and where appropriate testing them.”

Sources have indicated to Beef Central that one case involves a stud/commercial cattle breeding enterprise and the other involves a commercial operation.

On the stud operation, which has not been identified, it is understood that all offspring from the bull involved have been slaughtered, and all young bulls remain on the property.

Minister convinced lab capacity up to standard

Meanwhile, Queensland minister for agriculture John McVeigh has rejected claims that forthcoming laboratory closures and the reliance on a single lab in Brisbane from March onwards could result in BJD testing time-frames for affected properties being stretched well beyond the expected three to four month period.

It follows statements by a serving biosecurity officer on Wednesday that the loss of experienced scientific and technical staff as a result of the closures could jeapardise BJD testing efforts. 

In relation to BJD testing, Mr McVeigh said three senior microbiologists are currently working for Biosecurity Queensland, with one located in each of the Townsville, Toowoomba and Coopers Plains laboratories.

Mr McVeigh said that with the consolidation of veterinary testing to Coopers Plains there will be two senior microbiologists located at that facility.

To date, all faecal and tissue culture undertaken by Biosecurity Queensland as part of the BJD investigations have been conducted at the Toowoomba facility.

Mr McVeigh said this would continue until services are transitioned to Coopers Plains in the next three months.

He said training had also been undertaken to ensure ongoing retention of microbiology expertise in veterinary diagnostics for Queensland.

“I have visited both the Toowoomba and Coopers Plains Laboratories on the 18th and 19th of December with senior departmental staff to specifically confirm that our labs were up to the BJD task.

“Having done that, and having talked to staff at both sites, I'm convinced they are.

“I have further satisfied myself of this in studying progress of the industry transition committee's reports, in industry meetings, and in discussions with officials from other States.

“It is my opinion that the period of transition, training and backup services from the former lab system to the state of the art system at Coopers Plains, which was always to be completed by the end of this financial year, means that at present we will in fact have more lab resources available for the BJD situation in the coming months than we would have had previously.”


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