Bluetongue virus has been detected in seven dairy heifers near Echuca, forcing authorities to establish a 50km designated virus zone as they determine the source.
The virus was detected in three 12-month-old heifers near Echuca on October 14 during pre-export testing, before a further four heifers were found to be affected at the property.
The detection of antibodies in the heifers’ blood indicates previous exposure to BTV, with one heifer believed to have been exposed to the virus in NSW where it is more prevalent.
The cattle were not showing signs of clinical bluetongue disease and no virus was detected in the animals’ blood.
A zone of possible transmission of 50km has been established and a further buffer zone of 50km of detection established around the property while surveillance activities are undertaken, and these will remain in place for a total of 30 days from the date of detection.
Victoria’s chief veterinary officer Charles Milne said it was an ‘‘unusual’’ situation that Agriculture Victoria would continue to monitor.
‘‘What we’ve detected is evidence of past infection and we’re undertaking an intensive surveillance of 50km around the farm to ascertain if there’s been any spread and how it came to be within that area,’’ Dr Milne said.
‘‘There’s no movement restrictions from farms that have been affected. The purpose is entirely to satisfy export partners who require these animals to be free of viruses.
‘‘Agriculture Victoria staff will be contacting producers in the area to seek their assistance and make arrangements for on-farm sampling of cattle.
‘‘We would ask the farming community to co-operate with the exercise so we can rapidly understand how the animals came in contact with the virus.’’
Rochester Veterinary Practice’s Mitch Crawford said there was no cause for alarm at the announcement.
‘‘The first thing is: don’t panic, because it doesn’t cause any disease in Australia as far as we know,’’ Dr Crawford said.
‘‘(The virus) does exist in northern Australia, and that provides some trade restrictions, but the virus is transmitted from cow to cow by biting insects that to our knowledge are not in Victoria.’’
The viral disease is spread through flying insects called midges and affects ruminants including cattle, sheep, goats, buffalo and deer.
Clinical bluetongue disease has not been recorded in any livestock species in the field in Australia, with the exception of two minor incidents in sheep in Darwin in 1989 and 2001.
Dr Milne said there was no risk to humans from BTV, nor was there any food safety issue associated with livestock products.