Theileria infection is caused by Theileria orientalis, a parasite transmitted by ticks when they feed on the animal’s blood.
There is a heightened risk of Theileria infection, especially in the North Island, as the tick population is likely to have increased thanks to a dry summer and a mild winter.
Theileria orientalis has been present in NZ for about 30 years and is in many countries around the world. It is not spread by direct animal-to-animal contact in the absence of ticks. There are no human health or food safety risks associated with Theileria.
What to look for:
- Signs of anaemia in cattle include lethargy, pale mucous membranes, exercise intolerance and increased respiratory and heart rates.
- Cows lagging behind the rest of the mob when being shifted or lying down in the paddock.
- There are a number of causes of anaemia and its signs can be similar to those of other diseases.
What to do if cows show signs:
- Contact your vet for advice.
- Stress and movement of affected animals should be minimised because their reduced capacity to transport oxygen around the body can lead to collapse and death.
- Affected animals should be rested, given high quality feed and water and handled only when necessary.
Prevention and control for Theileria infection:
Cattle are at risk of infection 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.
The control of ticks is strongly advised. Farmers should be regularly checking their stock for ticks and treating animals as necessary.
- Treat new animals: Make particular effort to treat cattle before moving from one property to another.
- Young stock: Calves should be closely inspected for signs of anaemia.
- Manage the tick population: Inspect cattle for presence of ticks. Tick treatments can be useful to reduce the tick load and the severity of the disease.
- Ease any underlying disease or stress: For example, transition management, trace element deficiency, BVD, facial eczema.
If you suspect a case of Theileria infection, contact your veterinarian for advice.
For more information and a full fact sheet on Theileria, visit DairyNZ
