Elsie sourced this information about theileriosis from the 2013 Science and Innovation Award winner, Dr Abdul Jabbar who used his Dairy Australia award to research bovine theileriosis - a tick-borne disease that is similar to malaria in humans. This information was published in an article 'Changing nature of tick disease', Farming ahead, 1 September issue.
It is possible ti transmit the Theileria parasite directly from animal to animal through management procedures such as drenching and vaccinating with multi-use guns, castrating and ear notching.
In endemic areas, such as the mid north coast, bovine anaemia caused by the Theileria parasite is typically seen in calves 8 to 12 weeks old. Immunity then develops at about 6 months of age, so the disease is seldom seen in adult cattle in these regions.
If infected cattle are moved to a naive herd, cattle of any age will be susceptible, and pregnant cows that become infected may abort or have a still birth.
While some cattle will become very ill and die when they contract bovine anaemia, most will survive the infection and gain immunity to the disease.
In outbreaks in Victorian herds in typical physical symptoms (some of which were displayed by Bradley's cattle) include high temperatures of more than 39.5C, rapid weight loss, slobbering, extreme lethargy, being jaundiced pr anaemic or both, a very poor exercise tolerance and the odd cow becoming very aggressive and dangerous to handle.
While the bush tick is thought to be the main transmitter of Theileria parasites. other tick species could be involved and lice and march flies have been shown to transmit the disease in laboratory experiments.
For Chris Bradley, the disease seems to have disappeared from his herd, with no symptoms being seen in any cattle in the past year. The cows treated with oxytetracycline during the original bovine anaemia outbreak have made a slow but complete recovery. Chris credits the limited deaths in his herd to the local veterinarians, who regularly came out and blood tested 50 animlas from four difference herds to monitor the disease spread and number of affected cattle.
There is currently no vaccine available for Theileria-induced bivine anaemia in Australia.
Further information on research into The development of a Bovine Theileriosis vaccine.