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 was associated with anaemia and death in cattle.
DairyNZ technical veterinary adviser Dr Nita Harding said cattle were at risk when moved to areas where infected ticks were present. Likewise, if an infected animal was transported, it could 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.”
Harding said it was important farmers remained vigilant and monitored 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 runoff 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.”
Harding said more South Island cases were likely, especially in Nelson-Marlborough, where ticks were known to be present.
