Hendra Virus

13th June 2019

As many will have heard already, there has been a confirmed case of Hendra Virus in a horse approximately 30km east of Scone in June 2019. The affected horse was 25 year old unvaccinated mare which had not left the property for some years. The mare had been treated for neurological symptoms from Friday to Sunday before being euthanased. A sample was taken post-mortem for Hendra exclusion testing which has subsequently confirmed that the mare was infected with Hendra Virus. At this stage it is thought that source of infection may be a colony of flying foxes which have been roosting in the area for some time but this has not been confirmed.

Hendra Virus: Some brief facts…

  • Hendra Virus was first identified in Brisbane in 1994. Since that time sporadic outbreaks have occurred along the north-eastern coastline of Australia from Cairns in the north to Kempsey in the south. These outbreaks have resulted in 4 human deaths and approximately 100 horse deaths.
  • Fruit bats/flying foxes are generally considered to be the host species for Hendra Virus and infection of horses is thought to be through exposure to feed and water contaminated with bat faeces or urine. Human infections have subsequently occurred from close contact with secretions from infected horses.
  • The virus is not thought to survive in the environment for extended periods and is not considered very contagious. As such the risk of transmission from bats to horses to humans is low HOWEVER THE CONSEQUENCES OF INFECTION ARE EXTREME (100% mortality in horses and >50% mortality in humans).
  • The symptoms of Hendra Virus infection in horses varies widely and may include any number of the following:
    • Inappetance
    • Lethargy
    • Fever
    • Respiratory signs
    • Neurological signs
    • Colic

As such, it is impossible to diagnose or exclude Hendra Virus on examination alone. A definitive diagnosis can only be made with a blood test which may take up to 3-4 days to complete. The disease will generally worsen over 24-72 hours leading to death/euthanasia.

What does this mean for horse owners in the area??

There is no need to panic in light of this development. The risk of horses contracting Hendra virus is still relatively low (getting lower the further west we go). It is important that steps be taken to minimize potential contact between horses and flying fox faeces/urine in areas where bats are known to be present. Feed and water troughs should be placed in protected areas where possible and fruit trees fenced off to prevent horses grazing underneath.

Additionally, an effective vaccine has been available for several years which has proven to be the most effective means of protection against contracting Hendra Virus. We would strongly recommend vaccination for the following:

  • Horses travelling to or near any areas with a history of Hendra infections
  • Horses which may come into contact with flying fox excrement (remembering that flying foxes can travel upwards of 30km from their roost at night)
  • Anyone that wants to put their mind at ease and all but eliminate the risk (however small it may be) of their horses contracting Hendra Virus

Again, we would reiterate that whilst the existing chances of Hendra Virus infection in your horses are small, the consequences are likely to be tragic and that those most likely to be affected are yourselves, your families and veterinarians.

What is involved with vaccination??

The Hendra vaccination involves the following schedule:

  • 2 initial doses 3-6 weeks apart
  • 1 dose 6 months later
  • Annual boosters

For the vaccination status to be entered onto the national registry vaccines must be administered by a registered veterinarian and all vaccinated horses must be microchipped for identification. If the vaccine status lapses (there are a few weeks grace) then the schedule must be restarted.

It is important to note that in the event of an outbreak, in contact horses that can demonstrate that they are up to date with their vaccines will be cleared to travel whilst non-vaccinated horses will be subject to significant quarantine restrictions.

If you have any further queries regarding Hendra virus and your horses please do not hesitate to call us at the clinic on 6377 1258.