Sheep parasites

Page last updated: Wednesday, 18 October 2017 - 2:40pm

Please note: This content may be out of date and is currently under review.

The impact of parasites on sheep can range from being virtually undetectable, through to obvious clinical signs or even death. Symptoms are often aggravated by periods of stress such as lambing, weaning and poor nutrition. Control and eradication (where possible) relies on sound management and correct application of veterinary chemicals.

Important parasites of sheep and lambs in Western Australia (WA) include both internal and external parasites. These parasites cause significant losses in sheep flocks but management techniques can be effective. The following web pages provide information and advice on how to best manage these parasites.

Scour worm

​The main worms that affect sheep in WA are the scour worms, including brown stomach worm (Teladorsagia, or Ostertagia) and black scour worm (Trichostrongylus) which can cause ill thrift, diarrhoea and, in severe cases, death. 

Barber's pole worm

Barber's pole worm, which can cause anaemia (visible as pale mucous membranes of the gums and around the eyes), subcutaneous oedema (bottle jaw) and sheep deaths, can also be a major problem in some areas.


The main costs associated with managing these parasites are chemicals and labour involved in applying treatments as well as reduced productivity. Other costs include those associated with increased occupational health and safety risks for operators and for shearers, wool classers and others handling treated sheep or wool.


Reducing the risk of flystrike has immense benefits to the health and wellbeing of sheep, the people who work with them and business/farm productivity. Predicting your risk of flystrike will depend on environmental conditions as well as how susceptible your sheep are.

Sheep measles

'Sheep measles' or 'Cysticercus ovis' is the name given to the cystic intermediate life cycle stage in sheep of Taenia ovis, a tapeworm parasite of dogs. If detected at slaughter, the small cysts in sheep muscle must be trimmed, or if severe, the carcass condemned, causing financial loss to the producer or abattoir.

Liver fluke

This serious parasite of ruminants and some other animals is not present in Western Australia, and a stringent quarantine process is in place to prevent its introduction from other states. It is essential to ensure familiarity with the entry requirements before importing livestock or horses into WA. 

Contact information

Danny Roberts
+61 (0)8 9892 8535