Theileria now found in herds

The cattle disease theileria, traditionally causing sometimes fatal parasitic anaemia in single animals, is now being reported in herds.

The Theileria orientalis parasite transmitted by cattle ticks has been recognised in Northland, Auckland and the Waikato since 1982, and until recently was considered a disease affecting only debilitated animals.

But since spring last year it has been identified in 46 herds, mainly in the three northern regions but including one herd in the Bay of Plenty and another in Canterbury.

A recently identified strain of theileria called Ikeda is understood to be linked with the herd outbreaks.

There is no vaccine or treatment for the disease, which only affects cattle - there is no human or food safety issue.

Ministry of Primary Industries (MPI) veterinarian Dr Andrew McFadden said 70 deaths had been reported, but that was an estimate.

Of the infected herds, 15 were in Northland, mainly calves and young cattle infected last spring but including some dairy cows from the Waikato which had not been exposed to the disease before they were brought north.

Most of the 46 infected herds were in South Auckland and Waikato, Dr McFadden said. The Canterbury case was an isolated incident involving an embryo transplant animal.

"Distribution of the disease is confined to areas of tick infestation, so climate and other factors affecting ticks are involved." It is likely tick populations increased during the recent drought.