Hendra virus factsheet

Hendra virus (HeV) is a disease transmitted to horses by flying foxes (bats). On rare occasions, infected horses have caused disease in humans. Victoria has not recorded a case of Hendra virus, but continued vigilance is imperative to protect human and animal health.

What is Hendra?

Hendra is a sporadic viral disease of horses (and rarely humans) caused by a Henipavirus.

Pteropid bats (flying foxes) are the natural reservoir of the virus and do not develop clinical disease.

Research suggests that one of the highest transmission risks is contact with bat urine when horses feed or water in areas frequented by bats. Black flying foxes and Spectacled flying foxes have been linked to previous Hendra outbreaks.  However, there is still evidence of the virus in local Pteropid bat species (i.e. Grey-headed flying foxes).

How is the virus spread?

Transmission of the virus requires close contact.

The exact route of transmission of Hendra virus is not fully understood, but it is thought that horses become infected through close contact with body fluids/excretions such as urine and/or birthing fluids from Pteropid bats species (flying foxes).

Contamination of feed and water sources beneath bat roosts have been identified as potential sources of infection.

Other risks include indirect contact with contaminated equipment. All bodily secretions (e.g. nasopharyngeal secretions, blood and urine) and tissues are potentially infectious from animals carrying the virus.

What species are affected?

Natural infection has been seen in horses and humans, however dogs have also demonstrated exposure to infection on properties where horses have tested positive.

Experimentally, other species such as cats, pigs, ferrets, guinea pigs and mice have also shown signs of clinical disease, but this has not been associated with cases of natural infection.

Pteropid bats (flying foxes) are the known natural reservoir of Hendra virus and usually show no signs of disease. Horses are the only species known to have been infected naturally from bats.

Can the virus spread to humans?

The transmission of Hendra virus from horses to humans is a rare event, but the consequences are serious. Of the seven human cases diagnosed, four have died.

The common risk factor in these cases has been close occupational contact with horses.

Direct transmission from bats-to-humans, human-to-human, or other species-to-human has not been recorded.

What are the human symptoms of Hendra virus?

Human infections with Hendra virus range from mild influenza-like illness to severe respiratory disease (pneumonia) or neurological disease (meningitis and encephalitis). Onset of illness usually occurs between 5-21 days after exposure to an infected horse.

Symptoms of infection in a person can include fever, headache, dry cough, sore throat, breathing difficulties, dizziness, unusual sleepiness and confusion.

If you are concerned you have been exposed to Hendra virus you should immediately seek medical advice, i.e. general practitioner, or local hospital.

I think I have Hendra - What should I do?

Medical advice should be sought immediately if you have been in close contact with infected animals or materials.

What are the clinical signs of Hendra virus in animals?

Typically, HeV infection causes an acute illness that is rapidly fatal, however some cases have shown variable and sometimes vague clinical signs.

Signs have included fever, increased heart rate, difficulty and/or rapid breathing, depression, weakness and neurological signs such as an uncoordinated gait, head tilt, muscle twitching, apparent vision loss and/or aimless walking.

The incubation period in natural infections has ranged from 5-16 days.

There are no specific or unique clinical signs for HeV infection in a sick animal.

What do I do if I suspect Hendra in my horse?

Hendra disease is a notifiable exotic disease and any suspected or confirmed cases must be reported immediately to Agriculture Victoria on the Emergency Animal Disease Watch Hotline 1800 675 888 (24/7) or to your local Agriculture Victoria Animal Health and Welfare staff.

Horse owners should regularly monitor the health of their animals and immediately report any unusual signs of disease.

Avoid close contact with the sick horse and any other animals that have been close by until testing can determine if Hendra virus is present.

How can I reduce the risk of horses becoming infected?

The single most effective way to reduce the risk of Hendra virus infection in horses is to vaccinate. Annual boosters, (following the initial priming course of injections) have been proven to protect horses from infections and reduce shedding in clinical cases.

Isolate new horses to your property, especially if they have  travelled or co-mingled at equine events with horses from areas where Hendra cases have been previously detected (i.e. northern NSW or Queensland). Carefully monitor their health and report any signs of illness early.

Remove horse feed and water containers from under trees where flying foxes may be roosting or feeding.

Note: The destruction or relocation of flying foxes is not an effective risk management practice and is illegal. Flying foxes are a protected species and play an important ecological role. There are more effective ways of reducing the risk of Hendra disease.

How can I reduce the risk of exposure?

Appropriate use of Personal Protective Equipment (PPE) has proven to be highly effective against contracting illness. There have been no reported cases of Hendra in people who have been wearing PPE.

Practice good hygiene principles when wearing PPE;

  • avoid touching your mouth, eyes and nose,
  • cover any cuts or grazes with a water resistant dressing under PPE (i.e. Band-Aid),
  • do not eat or drink whilst wearing PPE,
  • Thoroughly wash hands and face after removing PPE & shower before handling other animals.

When working on properties and in-contact with potentially infected animals or materials;

  • Waterproof footwear, i.e. gumboots
  • Disposable overalls
  • Gloves
  • P2 facemask (minimum) - Full face powered air respirator preferred
  • Protective eyewear

When working on properties without contact with potentially infected animals or materials (i.e. working >5m from an infected animal/site);

  • Waterproof footwear, i.e. gumboots
  • Disposable overalls
  • Gloves

Any additional recommendations or requirements will be provided by Agriculture Victoria based on a case-by-case assessment of the risk.

How can I reduce the risk of spread?

Good hygiene, appropriate use and decontamination of PPE and thoroughly washing/disinfecting yourself and any materials/vehicles before leaving an infected property will protect you from spreading the virus to other people or animals.

Infection has primarily been seen in horses, however dogs have also demonstrated exposure to infection on properties where horses have tested positive.

It is recommended to shower and launder all clothing worn during your deployment before engaging with other people or handling your own animals. Any additional recommendations will be provided by Agriculture Victoria on a case-by-case basis.

What is the government’s response to Hendra?

Hendra virus is a serious risk to human and animal health. Agriculture Victoria in consultation with you and your veterinarian will manage any suspect or confirmed case/s.

The affected property will be placed under quarantine until there is sufficient evidence that Hendra virus has been controlled.

Horses and other susceptible species will be tested and their health monitored for any signs of Hendra virus infection. Tracing of any horse movements associated with the affected property will also be undertaken.

Any decision to euthanase infected horses, (or other animals) will be made on a case-by-case basis. This decision will be made by Agriculture Victoria based on the welfare of the infected animal, human health risks, biosecurity risks and in consultation with the owner.

Vaccination of horses against Hendra virus is an effective means of preventing infection in horses.

Further information

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Page last updated: 01 Feb 2023