More efficient testing is in the pipelines but it’s several years away.
Tests being used are adequate to determine the need to cull infected and extremely high risk animals.
Contrary to some farmer and industry perception the response is certainly not doing half-done testing, Roche said.
The test are not 100% reliable but are the best available and doing the job effectively enough to confidently make calls on culling herds.
“There is no accurately precise test but these tests are not as inaccurate as some may believe. They all have indicators of something there.
“We are very confident when we make a call to depopulate that there is either an absolute positive for presence of the disease or indicators of extremely high risk.”
Roche said following the advice of the technical advisory group (TAG) after last spring the call on depopulation changed.
“They said we needed to start depopulating on the basis of the Elisa results and this means there may not be an absolute positive but when the indicators are all weighed up the herd is deemed extremely high risk of spreading the disease.
“If we get forward movement of animals off an infected farm we depopulate all those animals.
“This is such an infectious disease these animals will pass it on. They do have to go.
“I can understand the confusion because a farmer may have animals off that infected farm and they may not have a positive PCR test but it is too great a risk not to take those animals if it’s proven they have moved during the time of infection.”
Roche said diagnosing the disease is hugely challenging and testing is only part of it.
“Tracing forward and back movements is fundamental to the eradication and management of the disease.
“If we didn’t have the problem with Nait compliance we could trace off infected farms so much more quickly and we would close down high-risk farms very quickly, that would slow down the spread and help with depopulation.”
Work is being done internationally to see if it’s possible to trace the bacteria in an animal’s body once it’s been exposed to the disease.
“It is possible that where this bug goes and hides would be sending out signals that we’re not yet looking for and could lead to being able to test for M bovis when the cattle are not actively shedding the disease.”
Last month MPI put out a worldwide call for diagnostics research proposals. The Government has committed $30 million for science investment to support the eradication programme.
Roche said the focus is on diagnostic tools that will contribute towards national surveillance testing and on enhancing diagnostic test performance at the herd level.
The group is also interested in tools that can be used on germplasm.
So far the response has been encouraging.
“There’s a bunch of diagnostic experts around the world lining up to apply for the fund to develop a test that will be highly sensitive.
“Our desire is that test will identify the presence of M bovis when the animal is not shedding. It will be a far more sensitive test than PCR or Elisa.
“We are just through year one. It will be year four onwards before we have a test that will pick up the disease more accurately and more rapidly.”
The science group is also looking for people to make the existing tests more sensitive.
“That could be in our sampling, extraction methods or the laboratory methods we are using.
“There are companies overseas that believe they can improve the methodology we are using and that would speed up detection of the disease.
“I am confident we are getting ahead of this disease. We will keep battling with what we have got,” he said.
Note: this story has been corrected to clarify which animals will be culled without the need for testing.
