Hendra virus: managing the risk in Western Australia

Page last updated: Tuesday, 7 June 2022 - 3:01pm

Please note: This content may be out of date and is currently under review.

Hendra virus is an emergency animal disease transmitted to horses by flying foxes (fruit bats). While Western Australia has not recorded a case of disease caused by Hendra virus, small concentrations of flying foxes are present in northern WA and the Gascoyne region and there is some risk of infection.

Through close contact, Hendra virus can spread from flying foxes to horses and occasionally from infected horses to people.

Horse owners should remain vigilant for signs of Hendra virus in horses.

Hendra virus at a glance

  • Hendra virus is a disease carried by flying foxes (fruit bats) in Australia, Papua New Guinea and surrounding islands. Hendra virus was first diagnosed in Australia in 1994.
  • While the virus does not visibly harm flying foxes, it can occasionally spread from flying foxes to horses, and from infected horses to people.
  • Horses need to be in close contact with flying foxes to have some risk of becoming infected.
  • No horses or people in Western Australia have been diagnosed with Hendra virus infection, however there have been 87 confirmed cases of Hendra virus in Australia as of October 2021.
  • The likelihood of Hendra virus infection occurring in WA is considered low, because of the low numbers of horses where flying foxes occur, and the relatively low concentrations of flying foxes.
  • All four species of flying foxes on mainland Australia can carry the Hendra virus including the two species of flying foxes found in northern Western Australia and the Gascoyne. Small numbers of one of these species may occasionally be sighted in the Mid-West and the northern Wheatbelt region of WA. See distribution map.
  • Horses imported from interstate, especially Queensland or northern New South Wales or which have had contact with horses from these areas, should be isolated for 20 days and monitored for signs of Hendra virus.
  • People in close contact with infected horses have some risk of contracting Hendra virus. Four people have died from contracting Hendra virus from infected horses in Queensland.
  • A new variant of the Hendra virus has been identified which causes the same clinical signs and the severe illness as the original virus.
  • Vaccination is available for horses and protects against the known different Hendra virus variants.

Signs of Hendra virus infection

Hendra virus can cause a range of signs in horses, including:

  • rapid onset illness
  • increased body temperature (above 38.5°C) and heart rate
  • dullness or depression
  • rapid deterioration with either respiratory and/or nervous signs
  • respiratory distress; laboured breathing, clear, frothy and/or blood-stained nasal discharge
  • neurological (nervous system) signs such as wobbly gait, lack of coordination, apparent loss of vision, aimless walking in a dazed state, head tilting and circling, muscle twitching, urinary incontinence, inability to rise.

If your horse shows any of these signs, and may have had exposure to flying foxes, or to other horses that have had exposure to flying foxes, call your veterinarian or the Emergency Animal Disease hotline on 1800 675 888 immediately.

Minimise contact with the horse until you have received veterinary advice. Sick horses must not be moved from their location and should be isolated from other animals on the property.

How do horses catch Hendra virus?

Horses can be infected with the virus by having contact with feed, water or other items contaminated by the body fluids (urine, faeces) of flying foxes.

In some cases, infected horses have transmitted the virus to other horses via close contact with their body fluids.

As of October 2021, there have been 87 confirmed incidents of Hendra virus in Australia, resulting in the death of 107 horses. For up to date/current case numbers please refer to Summary of Hendra virus incidents in horses maintained by the Queensland Government.

Where are flying foxes found in WA?

Only the black and little red flying foxes are found in WA.

map of the distribution of the main flying fox species shows the distribution of the two species found in the north of WA.

The risk area for horses having contact with black or little red flying foxes is in northern WA, from Shark Bay in the Gascoyne region onwards. Small numbers of little red flying foxes may occasionally be sighted in the Mid-West and the northern Wheatbelt region, though not as often.

How can I reduce the risk of my horse catching Hendra virus?

WA horse owners can reduce the risk of their horses becoming infected by taking the following steps:

  • do not place feed and water containers under or near trees. If possible, place feed and water containers under a shelter.
  • remove horses from paddocks where flowering or fruiting trees may be attracting flying foxes. Return horses only after the trees have stopped flowering or fruiting and the flying foxes have gone. Clean up any fruit debris underneath the trees before returning horses.
  • if horses cannot be removed from the paddock consider fencing (temporary or permanent) to restrict access to flowering or fruiting trees or temporarily remove them during times of peak flying fox activity (usually at dusk and during the night).
  • vaccinate horses against Hendra virus.

What should I do if my horse shows signs similar to Hendra virus?

Hendra virus infection is a reportable disease — a disease that must be reported to government veterinary officers.

If your horse has signs suspicious of Hendra virus infection and may have had contact with flying foxes, or has recently arrived from Queensland, NSW, Victoria or South Australia, or has had contact with recently arrived horses from these regions, isolate the horse and contact your veterinarian or the Emergency Animal Disease hotline on 1800 675 888.

Should I vaccinate my horses?

Vaccination against Hendra virus in horses is available. Owners should consult their veterinarian about the option of vaccinating if their horses:

  • have any risk of contact with flying foxes
  • travel to Queensland or northern NSW, or
  • have regular contact with horses from properties other than your own.

No vaccine is 100% effective, so veterinarians and owners should still maintain good biosecurity when handling vaccinated horses and be vigilant for signs of Hendra virus.

At this stage the vaccine does not provide lifelong immunity and boosters will be required.

Information about the vaccine is available at Health4Horses and the Australian Pesticides and  APVMA pubCRIS database

Is vaccinating horses mandatory?

The Department of Primary Industries and Regional Development does not require horses to be vaccinated against Hendra virus and there are no import restrictions on unvaccinated horses into WA.

Some veterinarians who work with high-risk horses may only accept clients whose horses are vaccinated in order to reduce the risk to their health and safety.

What is the risk of horses bringing in Hendra virus from other areas?

Wherever flying foxes and horses have contact, there is a risk that horses could develop Hendra virus.

Horses travelling to and from northern WA may also have a risk of contracting Hendra virus if exposed to flying foxes.

It is advisable to isolate horses that have been in areas where there are flying foxes or in contact with horses that have been exposed to flying foxes for 20 days and to monitor for signs of Hendra virus during that time.

How do people catch Hendra virus?

People have also been infected with Hendra virus after very close contact with infected or dead horses. To date, seven people have been infected with the virus, and four of them have died.  All of these cases have been in Queensland or northern New South Wales.

To date, there is no evidence that people have caught the virus from other people or from flying foxes.

How can I reduce the risk of catching Hendra virus from my horse?

As infected horses can transmit Hendra virus to people, it is advisable that you do not have close contact with any horse with:

  • signs suspicious of Hendra virus, and which
  • may have had contact with flying foxes, or
  • has recently arrived from interstate or northern WA.

Immediately isolate the horse from other horses, people and animals, and contact your veterinarian or the Emergency Animal Disease hotline on 1800 675 888.

Guidelines for handling horses suspected of Hendra virus and for personal protective equipment are available on the Queensland Government website.

Other diseases that flying foxes can transmit to horses

In May 2013, two horses in Queensland died as a result of being infected with Australian bat lyssavirus. These are the first recorded cases of Australian bat lyssavirus in horses.

Three people in Queensland have also contracted Australian bat lyssavirus from contact with infected bats and died.

Although Australian bat lyssavirus is very rare, horse owners are reminded to minimise contact between any species of bat and their horses’ feed and water.

Safety advice for veterinarians

As Hendra virus signs vary considerably and there is a risk of disease wherever flying foxes frequent, veterinarians should always consider their safety first. Always assess the risk of Hendra virus before examining a sick horse and wear appropriate personal protective equipment (PPE).

If veterinarians see signs suspicious of Hendra virus, they should immediately ring the Department's Diagnostics and Laboratory Services - Animal pathology unit on +61 (0)8 9368 3351 or the Emergency Animal Disease hotline on 1800 675 888 for advice on correct PPE.

The most recent ‘Hendra virus information for veterinarians’ is available on the Queensland Government website. The Australian Veterinary Association also has a video describing the use of PPE.

Contact information

Michael Paton
+61 (0)8 9368 3627