Vets from the Cumberland Livestock Health and Pest Authority (LHPA) are advising cattle producers to be alert to the risk of theileriosis in cattle, following recent cases involving significant losses in cows that were introduced from areas west of the Great Dividing Range.

Keith Hart, Cumberland LHPA Senior District Vet, says the blood parasite called Theileria destroys red blood cells, resulting in anaemia in affected animals.

"The signs accompanying the anaemia include weakness and lethargy, fever, pale and/or yellow gums, going off feed, late term abortions or stillbirths, difficulty calving, and death. Late-pregnant cattle are the category which is most susceptible to the disease," said Dr Hart.

"The parasite is spread to susceptible animals by blood-sucking parasites, especially bush ticks. Blood sucking flies such as March flies may also be involved."

Dr Hart said that most local cattle are generally exposed to the parasite at a young age, therefore developing immunity before they become pregnant. Local cattle may show clinical signs, but the disease is much more common in introduced cattle which have no immunity.

"The animals we typically see affected with Theileria are adult animals introduced to the coastal area from regions that have few or no ticks, as observed in the recent cases. These animals have not been exposed to Theileria and their immune system can be overwhelmed resulting in clinical disease," he said.

"Cows or heifers late in pregnancy appear most at risk, presumably due to the extra stresses associated with pregnancy which can result in abortions and deaths."

Dr Hart said the treatments available in Australia are limited but a more effective drug used overseas is currently being evaluated by veterinary authorities.

"Affected cattle are generally treated symptomatically, including good nursing care, reducing stress and providing high quality feed. Unfortunately there is currently no vaccine available," he said.

"Investigate whether the desired genetics are available from coastal cattle studs, and if buying females outside the area consider buying unjoined animals and joining them locally. Introducing cattle during the winter months will minimize exposure to bush ticks.

"Introduced animals should be kept separate from resident cattle and monitored closely especially in the first three months. A tickicide effective against bush ticks should be used to minimise tick burdens."

Producers are advised to seek veterinary advice if cattle are showing any of the clinical signs described above. More information is available at www.dpi.nsw.gov.au/biosecurity/animal/info-vets/theileria

Source: Cumberland LIvestock Health and Pest Authority