Kunjin virus disease

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Kunjin Virus Disease

Kunjin virus disease is a viral infection affecting horses in mainland Australia and Papua New Guinea. The disease is caused by a flavivirus (Kunjin virus), which is closely related to West Nile virus which affects horses living in North America, Africa, and Europe. Kunjin virus has caused outbreaks of neurologic disease in horses. In 2011, more than 1000 horses were affected by an outbreak that occurred in New South Wales, Victoria, and Queensland.

How Kunjin Virus is Spread

Kunjin virus is spread from bites from the common banded mosquito, Culex annulirostris. This mosquito breeds in fresh water and tends to be found in spring, summer and autumn around natural wetlands and irrigation waters. The mosquito is especially common around the Murray Darling River basin areas in NSW during summer and into autumn. This mosquito tends to be most active after sunset and around dawn.

There is no specific treatment available for horses with Kunjin virus disease.


Mild colic
Muscle fasciculations
Increased sensitivity to touch and sound
Facial paralysis


  • History
  • Clinical signs
  • Physical Exam
  • Laboratory tests



Supportive care


  • There is currently no vaccine against Kunjin virus disease
  • Minimize the presence of mosquitoes at horse stables
  • Apply mosquito repellent. The most effective repellents contain either diethyl toluamide (DEET) or picaridin.
  • Dress horses in fly sheets and fly masks
  • Keep horses up during peak mosquito biting hours, especially around dawn and dusk
  • Screen windows and doors
  • Remove stagnant water sources to prevent mosquitoes from breeding.
  • Stock ornamental ponds with mosquito-eating fish such as goldfish. Keep vegetation away from the water’s edge.
  • Screen rainwater tanks with insect-proof mesh, including inlet, overflow and inspection ports. Ensure guttering is not blocked and does not hold water.
  • Empty and clean water troughs at least once a week.

Scientific Research

General Overviews

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Risk Factors

  • Horses who are housed in rural NSW where there are rivers, wetlands, flooded areas or heavily irrigated areas.
  • Kunjin virus is more common in some parts of northern Australia.