A blood-borne, tick-carried parasite, which causes serious a disease in cattle, has been identified for the first time on the West Coast.

Theileria, which causes the disease theileriosis, was discovered in a 188-cow dairy herd on the West Coast in spring this year.

The strain has been associated with anaemia and death in cattle.

The Ministry for Primary Industries (MPI) has confirmed the population of ticks that infected the West Coast dairy herd came from either Canterbury or elsewhere on the West Coast.

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Yesterday it confirmed there were two cases of theileria in the South Island, but would not confirm where the West Coast the case occurred.

DairyNZ technical veterinary advisor Dr Nita Harding said cattle were at risk when moved to areas where infected ticks were present. If an infected animal was transported, it could spread infection to ticks in the new location.

"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."

Cases of the disease were usually higher in autumn and spring.

"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."

She said stock needed to be regularly checked for ticks or signs of anaemia.

"This is a disease that can result in serious illness and death of cattle, and has affected some herds quite badly."

Signs of anaemia in dairy cows included: cows straggling on the walk to the shed, increased respiratory and heart rate, pale udder, and yellow eyes.

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More South Island cases were likely now that the disease had been diagnosed there, especially in Nelson/Marlborough, where ticks were known to be present, she said.

"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."

The strain of the disease was first identified in Northland in late 2012. There are now over 1000 cases of the disease in North Island cattle and MPI has reported around 116 new cases since September this year.

Theileriosis is currently most prevalent in the Waikato.

Westland Milk Products (WMP) company secretary Mark Lockington said WMP had been working with MPI, DairyNZ and the West Coast farmer concerned since the outbreak was identified.

It was advising all of its shareholders, to ensure they knew the signs of the disease to look out for. The disease did not pose a risk to humans or to milk quality, but it could impact production through loss of condition or death in cattle, he said.

- Westport News