Theileriosis is a disease caused by a species of Theileria, a blood-borne parasite that only affects cattle and is primarily transmitted by ticks. A new strain of Theileria orientalis called ikeda was first identified in Northland in late 2012. This strain has been associated with anaemia and death in cattle.
The DairyNZ warning comes after the Ministry for Primary Industries (MPI) confirmed that a case of Theileria had hit a South Island West Coast farm this Spring. MPI has concluded that a local population of infected ticks in Canterbury or the West Coast was responsible for transmitting infection to the 188-cow dairy herd.
DairyNZ technical veterinary advisor, Dr Nita Harding, says cattle are at risk when moved to areas where infected ticks are present. Likewise, if an infected animal is transported, it can spread infection to ticks in the new location, in turn spreading disease to uninfected animals.
“We are concerned that there may be infected tick populations in the South Island now. This latest case was linked to cows being grazed in the Canterbury area and then being brought back to the West Coast,” says Dr Harding.
“It’s important that farmers remain vigilant and monitor stock, particularly weaned calves at this time of year."
“Cases of Theileriosis are usually higher in Autumn and Spring. However, at any time of year, if animals present with signs of anaemia, a veterinarian should be consulted.
“We are advising farmers to consider the risk of moving young stock to grazier or run-off properties where the level of tick activity and Theileria may be greater than on the home property. Stock should be regularly checked for signs of anaemia. Tick treatments may be helpful for reducing the tick load and severity of infection, and farmers should seek veterinary advice regarding the most appropriate treatment for their animals. This is a disease that can result in serious illness and death of cattle, and has affected some herds quite badly.”
Dr Harding says more South Island cases are likely now that the disease has been diagnosed there, especially in Nelson/Marlborough, where ticks are known to be present.
“At this stage, we just don’t know exactly the degree of infestation or location of local tick populations and therefore the level of risk to different regions in the South Island,” she says.
Dr Harding says Theileria is now widespread over the northern half of the North Island with cases diagnosed across Northland, Waikato, Bay of Plenty, Taranaki, the King Country, Whanganui and Hawke’s Bay. Cases have also been reported from the lower half of the North Island. MPI has reported around 116 new cases since September.
Advice on managing Theileria is available from www.dairynz.co.nz/theileria
Farmers should regularly check stock for ticks and treat animals as necessary.
- Treat any new animals – particularly before moving cattle from one property to another.
- Manage the tick population – inspect cattle for ticks. Tick treatments can reduce the tick load and severity of the disease.
- Ease underlying disease or stress – for example, transition management, trace element deficiency, BVD (bovine viral diarrhoea) and facial eczema.
Signs of anaemia in dairy cows
- Cows straggling on the walk to the shed.
- Increased respiratory and heart rate.
- Pale, rather than healthy pink, vulva.
- Pale udder, yellow eyes.
- Cows with no strength or energy to do anything.
DairyNZ Communications Manager
Tel 027 703 0211