Improved test for Johne's disease

After more than a decade of research in Australia and overseas, sheep and cattle producers can now benefit from a rapid diagnostic test for Johne's disease.

The new Johne's disease test reduces waiting times for a diagnosis from three months to one week, decreasing the risk of further disease spread and reducing stress on affected producers.

The test, known as the High-Throughput-Johne's assay or HT-J, was developed by researchers from the University of Sydney and the NSW Department of Primary Industries.

The research was part of a five-year, $6.4 million Johne's disease project led by Professor Richard Whittington, of Sydney University, and funded by the Meat and Livestock Australia Donor Company, in partnership with Animal Health Australia.

The research team included Karren Plain, Ian Marsh and many collaborators across the livestock sector in Australia.

According to Professor Whittington, the test's development threw up plenty of challenges for the team.

"This test is the culmination of at least a decade of very difficult research here and elsewhere," he said.

"Most animals become infected with the disease in the first one to 12 months of life, but don't show signs of disease for years.

"They only shed minuscule amounts of bacteria in their faeces, which makes it very hard to detect, but they are capable of infecting other animals and properties if sold.

"The challenge for us has been to try and detect the smallest quantity of Johne's disease bacteria in faecal samples."

After being approved by the Sub-committee on Animal Health Laboratory Standards, the HT-J underwent a trial by fire when Bovine Johne's disease was discovered in north Queensland in November, 2012.

Intensive use of the new test revealed weaknesses, including the delivery of inconclusive results, which prompted industry-wide collaboration from researchers and laboratory technicians to refine the HT-J.

MLA animal health and biosecurity project manager Johann Schroder said the test allowed affected producers to more quickly adopt corrective or remedial management strategies.

"The more quickly you can get a Johne's disease diagnosis, the more quickly you can stop further spread of the disease," he said.

"It also reduces stress on producers - they no longer have to wait three months to find out if their property is affected or not."

Professor Whittington said the new DNA test removed the delays associated with the culture test, but was not foolproof.

"Producers must work closely with their relevant veterinary services to interpret test results at a herd-flock level, and then properly deal with Johne's disease," he said.