AUSTRALIA is stepping up its frontline defence against bluetongue viruses by establishing herds of cattle to act as sentinels in northern neighbouring countries.
A sentinel herd on a commercial beef operation in Papua New Guinea is already providing regular blood samples and moves are underway to have a herd of Balinese cattle routinely monitored in East Timor.
Staff from the Northern Territory Department of Primary Industry and Fisheries’ Berrimah Veterinary Laboratory have just returned from a trip to Timor-Leste where they met with that country’s government representatives to map out the possibilities for such work.
Principal veterinary officer virology Dr Lorna Melville said sentinel herds in neighbouring countries had been talked about for some time and recent Federal Government injections of funding for improved biosecurity has helped provide the means.
A laboratory has been previously set up in Timor-Leste and the next step is establishing the infrastructure needed to collect blood samples from cattle.
While some serology would also be conducted for foot and mouth disease, the main purpose would be monitoring bluetongue viruses (BTVs).
“We can’t stop BTVs from coming into Australia because we can’t put up quarantine barriers preventing insects blowing in,” she said.
“So monitoring and early warning is our main line of defence.”
Sentinel herds, which monitor what is occurring endemically, operate in about 90 locations in Australia, and involve all beef breeds, crossbreeds and dairy cattle.
Cattle breed does not influence infection rates.
BTVs are present in most of Queensland, around half of the NT and in some areas of NSW - depending on seasonal conditions the viruses can be detected south of Sydney and in other years they are contained to the North Coast.
In WA, mostly just the Kimberley and, in some years, small areas of the Pilbara are affected.
“The BTVs in Australia don’t make cattle sick, however some strains would make sheep sick if they got into sheep country,” Dr Melville said.
“Sentinel herds are about monitoring movement so our livestock industries can be prepared - there are vaccines available and measures producers can take.”
For southern areas, particularly NSW where most of the sentinel herds are, BTV management is very much a trade issue.
Some of Australia’s key, most lucrative, livestock trade markets, such as parts of the Middle East, will not take stock from BTV zones.
The breeder cattle market to China and potential of the live slaughter and feeder cattle trade is also affected as China has stipulated supply must be from BTV-free zones.
The NT research farm south east of Darwin, Beatrice Hill, has a sentinel herd of 24 head which acts as the ‘early warning’ site for the detection of viruses, particularly bluetongue, in Australia.
“Of the 200 species of biting midges in Australia, only five are capable of spreading BTV,” Dr Melville said.
“At Beatrice Hill, we take samples weekly and look for evidence of both insects and viruses.
“Modelling work has shown the origin of insects arriving in Darwin is most likely East Timor and some eastern parts of Indonesia so it will be very beneficial for us to know what is up there.”
Dr Melville said there was one serotype that could cause significant disease in cattle. It was currently found in Europe and Africa but not yet identified in Asia.
“We are particularly interested in finding out if that one is getting any closer to Australia,” she said.
Providing general veterinary pathology and laboratory training for nations on our doorstep made good preventative sense, Dr Melville said.
Farmers and vets in those nations were very keen to be involved.
“They can also be testing for diseases they are concerned about at same time as testing for bluetongue for us,” she said.