DairyNZ is asking farmers to watch out for the tick-bourne disease, theileria, when moving stock between properties.
Theileria Ikeda is an infection which causes anaemia in cattle and death in some cases.
It was discovered in Northland in 2012 and in March this year, the number of infected herds sat just below 1300 in the North Island and three in the South Island.
Farmers should not refrain from moving cattle, but they needed to be aware of signs of illness, DairyNZ's technical policy advisor Nita Harding said.
There had not been an increase in the number of infected herds, but it was important for farmers to be aware in areas where theiIeria was present, she said.
"We are certainly aware that there have been cases Theileria in the Manawatu and Whanganui area and that there are continuing cases in the Waikato area."
Farmers needed to look out for animals that are anaemic, Ms Harding said.
"The sorts of signs that you would see is particularly in young stock, stock that aren't growing very well...the sorts of sign that farmers see in milking cows is cows that are out of order coming into the shed, that seems quite a good thing to be looking out for in the early stages."
Once animals had been infected with Theileria, it was permanent, but animals previously exposed to the disease could be more resistant to the severe clinical effects, such as severe anaemia, she said.