For enquiries and further information email: Theileria.referrals@fvs.co.nz
DairyNZ factsheets
"Theileria - clinical signs and blood transfusions" As presented by Dr Sarah Briggs of Franklin Vets, Te Kauwhata, to the  2013 NZ Veterinary Association Conference


Sclera(copy)Normal colour of the membranes in the vulva(copy)

Theileria orientalis is a parasite which lives in the red blood cells of cattle. 

To become infected a cow must be bitten by a tick which is carrying the disease. It is not spread by direct animal to animal contact.

There have been an increasing number of cases in the northern parts of the North Island over the past few years. Again this spring this pattern has continued with new cases appearing within the geographical area covered by Franklin Vets. The main problems have come from animals (both new herds and returning heifers) that have moved into the area from further south. We have continued to see cases in local stock, but these have been sporadic and in isolated pockets where we believe the animals have avoided infection until recently. In herds that have seen issues in previous seasons there have been very few cases on the whole.
Cattle can be infected with the Theileria parasite without necessarily showing any signs of clinical disease.  
Once the animal is bitten it takes about six to eight weeks for the parasite to build up to significant levels in the blood. At this stage the body reacts by trying to destroy the parasite. Because the parasite is living inside the red blood cells, the body attacks its own infected red blood cells (haemolysis) to destroy the parasite. Unfortunately this can lead to a huge loss in red blood cells which are responsible for carrying the oxygen around the body; this is known as anaemia and results in the following signs in affected animals;

  • Pale or yellow (jaundice) mucous membranes  i.e. the gums, the membranes inside the vulva and conjunctiva (the white around the eye)
  • Depression
  • Weakness
  • Inappetance
  • Abortion
  • Poor milk production

If you see any of the above signs, or would like more information about Theileria, please contact us.


Vulva-Colour-indication of Theileria