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Five of the eight highest cost endemic diseases of cattle and sheep are caused by parasites, according to the 2015 MLA-funded Priority list of endemic diseases for the red meat industries project that assessed the financial impact of endemic diseases on farm productivity. The five parasites highlighted were cattle tick, buffalo fly and worms in cattle; flystrike and lice in sheep.

Parasites that infest cattle, sheep and goats include internal parasites such as worms, flukes and protozoa, and external parasites such as flies, ticks, lice and mites.

Parasites of livestock can also be zoonoses, meaning they can also infect humans.

Parasitic infestations of cattle, sheep and goats that can lead to significant economic loss include:

Internal parasites

External parasites

Impact on animal health and welfare

The negative impact parasites have on the health and welfare of animal can include:

  • blood loss which, if substantial, can lead to anaemia and death
  • diarrhoea which, if severe, can lead also to death
  • reduced appetite, resulting in debilitated animals that are more susceptible to other diseases
  • transferral of diseases from one animal to another as some parasites can also act as vectors (carriers)
  • open sores on the skin of livestock from external parasites like flies
  • reduced grazing behaviour or agitation (fly worry) due to flu annoyance.

Impact on livestock productivity

These harmful effects can have a negative impact on the productivity of livestock by:

  • reducing growth rates
  • reducing reproductive rates
  • reducing income through condemnation of carcase parts at slaughter
  • reducing milk production
  • reducing fleece weight, fibre diameter and staple strength
  • damaging hides and fleeces
  • dausing death

Some parasites of cattle, sheep and goats are not found in Australia, for example screwworm fly and some types of mites. It is important to keep these parasites out of Australia. Good enterprise biosecurity entails being familiar with parasites of the region, and being on the lookout and ready to report anything unusual.

Parasite problems after floods

Following floods (or significant amounts of rain), the populations of biting insects (buffalo fly, midges, mosquitoes and stable fly) and ticks can increase dramatically.

It is important to be aware of this and implement proper control measures to prevent animal welfare issues and losses in productivity.

More information on parasite problems in animals after floods can be found on the QLD Primary industries and fisheries website.