Bovine anaemia caused by theileriosis
There is no specific treatment or vaccine to build immunity to theileriosis so it is important for cattle producers to manage the risk. In Australia, this disease can be managed by following an integrated plan that focuses on prevention.
Prevention and management
- When buying in new stock, ascertain their health status, particularly avoid buying animals from known affected properties or localities. A laboratory test could be utilised to assess the presence of Theileria before purchasing cattle (see Professional service providers).
- Quarantine new stock, check for the presence of ticks and consider treating with a chemical registered for the control of ticks on cattle. When using insecticides, make sure you observe the prescribed withholding periods before marketing products of treated animals.
- In areas where Theileria are commonly found (generally coastal areas, see Figure 1), source cattle locally.
- In endemic (where the disease occurs regularly) areas where most adult cattle are usually immune, calves should be closely inspected when they are 6-12 weeks old.
- Introduced cattle into an endemic area should be examined closely when they have been in the district for 3-8 weeks.
- In districts where Theileria is normally not present, but cattle from an endemic area have been introduced, check home cattle regularly between 2 and 6 months after the introductions.
- If signs of disease are noted, seek veterinary advice as treatment when animals are mildly affected has been most successful.
- Careful attention to nutrition, worm control and trace element supplementation (if required) will minimise susceptibility to theileriosis.
- Avoid mustering, movement or otherwise stressing stock around calving when there is a high risk of the disease.
- If practicable, items such as castration knives should be cleaned and then disinfected between animals. Where not possible such as vaccinating a mob of cattle, use sharp needles and change regularly to minimise blood transfer.
- Bush ticks, wallaby ticks and bandicoot ticks (all in the genus Haemaphysalis) transmit Theileria and are almost impossible to eradicate from a property as they are on and off the host in a week or so, and live in pasture for many months, as well as infesting other animals including wildlife. See also control of bush ticks.
Figure 1. Theileria has the same coastal distribution as its Haemaphysalis tick host (bush tick distribution shown). Since 2006 a large increase in clinical outbreaks has been observed in south-east QLD, eastern NSW, southeast VIC and southern WA. Image adapted from Virbac.