Fighting the Threat of Theileria16 April 2012
AUSTRALIA - Parasites responsible for a cattle disease known as bovine anaemia caused by Theileria orientalis group (BATOG) are spreading in New South Wales (NSW) and Victoria.
Meat and Livestock Australia is collaborating with the NSW Department of Primary Industries (NSW DPI) and Queensland Department of Employment, Economic Development and Innovation (DEEDI) to research the distribution, significance, diagnosis and treatments for BATOG.
Previously called benign bovine theileriosis, the disease can cost beef producers up to $100,000 in prevention measures and production losses from anaemia, jaundice, abortions and mortalities.
Although the prevalence of BATOG remains relatively small compared to some cattle health problems, it is becoming more widespread.
The disease was confirmed on 191 NSW properties by 30 June 2011 and on 26 Victorian properties in October 2011.
But NSW DPI Cattle Health Coordinator, Dr Graham Bailey, estimated that at least twice as many properties with BATOG had been identified by veterinarians, and many more were likely to have cattle with Theileria parasites.
From surveys, Graham said beef herd costs associated with treatments, veterinarians, deaths and estimated production losses ranged from $300 to $100,000. The average cost to affected beef herds is $11,600 or about $67/head.
Testing of animal blood samples has been demonstrated as an effective detection tool for the main strains of Theileria orientalis parasites found in Australian herds.
Researchers have found that the rate of spread differs on individual properties, possibly due to vectors and other factors that need to be investigated to develop better prevention methods. Drugs registered in Australia for other diseases have low efficacy against Theileria parasites.
A number of chemicals are known to work against the parasite, including buparvaquone (BPQ), which was effective in one small-scale Australian trial. Investigations and negotiations are underway to make available an effective drug as soon as possible, including compliance with regulatory requirements and location of a willing supplier.
Of the few drugs that could potentially be used against Theileria orientalis infections, the most promising is buparvaquone (BPQ), which has been used effectively against exotic Theileria parasites overseas since the 1980s.
Researchers have studied the efficacy of BPQ to combat bovine anaemia caused by BATOG, but its residue levels in treated cattle need to be determined using a newly developed analytical method.
MLA-funded research is aimed at facilitating the supply and use of BPQ in Australia under permit and the possible future registration by the Australian Pesticides and Veterinary Medicines Authority.
Research project leader, Phillip Carter, said the drug dosages used were effective against the three main strains of Theileria orientalis parasites found in Australia.
“BPQ has been extremely effective in our pen trials, causing rapid reductions in local parasite species and variants once administered,” Mr Carter said.
“More research is now needed to see how effective the drug will be in clinically affected animals.
“As we cannot currently replicate the disease, this will need to be done during actual outbreaks on cooperating properties, and will have to wait until industry has regulatory approval to use BPQ.”
Dr Graham Bailey, is heading a team that will conduct a tissue residue depletion study for BPQ. The results will be used to determine meat residue levels and withholding periods for BPQ. The project findings will assist the registration process for BPQ.
TheCattleSite News Desk