The latest data from the Ministry for Primary Industries showed an increase this season, Veterinary Association Society of Dairy Cattle Veterinarians president Dr Jenny Weston said.
Naïve (unexposed) cattle moved into affected areas were particularly at risk.
Theileria, which caused anaemia in cows and was spread by ticks, affected cattle but was not a human or food safety issue.
Signs of Theileria included lethargy, low appetite, and reduced milk production.
Weston said vets played a key role in working collaboratively with farmers to provide advice, taking both a preventive and a proactive approach to minimise the disease.
“This includes knowing the risks for cattle, putting in place measures such as strategic tick control and managing movement of animals to reduce risk, and having a plan for early identification and management of affected animals.
“We urge farmers to remain vigilant and to speak to their local vet if they have any concerns about their cattle.
“Vets are on high alert and able to help monitor the situation for their farmer clients to identify infection early and put in place the best management practices currently available.”
Relying solely on tick treatments might not be effective as to prevent the disease, especially for animals such as cows moving to a new farm in another region, never exposed to Theileria.
“Sometimes it is not clear whether cattle have immunity to the disease or not and therefore it is recommended to check their status before moving.
“It is also important to give some thought regarding movement of pregnant dairy cattle next June.
“Movement of any naïve cattle to the endemic areas of the North Island places them at considerable risk of disease and broadly speaking is inadvisable.”
A new veterinary handbook on Theileria, released in July, comprehensively outlined the most effective strategies for differing farm circumstances.
It included up-to-date advice on treatments once animals were showing clinical signs, blood transfusions if appropriate, lowering stress levels by once-a-day milking, and keeping cows close to the dairy, as well as good nutrition and husbandry.
Methods of clinical diagnosis and herd screening to ensure early detection of affected animals were also included.
The handbook was developed by the Theileria Working Group and published by MPI and NZVA and included information to help vets to determine a whole-herd approach when individual animals were suspected or diagnosed.
“Vets are also receiving regular updates from both MPI and NZVA about Theileria so are up with the latest developments to assist farmers at this challenging time,” Weston said.
