The natural host for Hendra virus is the flying fox (fruit bat). Occasionally, Hendra virus can pass from flying foxes to horses. It causes severe illness, usually resulting in death.
On rare occasions, close contact with infected horses have caused illness in humans, with fatal consequences.
Hendra virus is a notifiable disease in Australia. This means it's a legal requirement to report cases of Hendra, even if there is only a suspicion of disease.
It is a rare disease and has only been detected in Queensland and Northern NSW. The death rate related to infection is very high — about 50 per cent in humans and more than 70 per cent in horses.
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:
- increased heart rate
- difficulty or rapid breathing
Neurological signs such as:
- uncoordinated gait
- head tilt
- muscle twitching
- apparent vision loss
- 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.
If you notice a sudden onset of illness in your horse or your horse has died suddenly, and you live in an area where there is a population of flying foxes that could come in contact with your horse, or your horse has traveled from Queensland or northern NSW recently contact your vet or the Emergency Animal Disease Hotline on 1800 675 888.
Protecting your horses from Hendra virus
Hendra virus is a low-risk disease for Victoria, but precautions should always be taken in areas where there are large flying fox populations in close proximity with horses, or with horses arriving in Victoria from Queensland or northern NSW.
An effective way to reduce the risk of Hendra virus infection in horses is to vaccinate. Annual boosters, (following the initial priming course of injections) has been proven to protect horses from infections and reduce shedding in clinical cases.
You can also minimise the risks by:
- removing horse feed and water containers from under trees where flying foxes may be roosting or feeding
- early isolation of a sick horse whilst awaiting veterinary attention
- good hygiene and cleaning practices
- 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 ( northern NSW or Queensland). Carefully monitor their health and report any signs of illness early.
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.
Vaccinating horses against Hendra virus
There is an effective vaccine to protect horses against Hendra virus that is available through vets.
Horse owners moving horses to Queensland or northern NSW should consider vaccination, as well as any horses that have been moved from these areas to Victoria.
Your horse is confirmed positive to Hendra virus
If your horse tests positive to Hendra virus your local vet will work with us to manage the situation.
The property where the horse is located will be placed under quarantine until all other horses on the property can be cleared of infection.
Once there is enough evidence to suggest that no other horses have been infected, the quarantine will be lifted.
Any decision to euthanise 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. Euthanasia of all infected horses is no longer mandatory.
For further information on Hendra virus please contact your local animal health staff on 136 186.
Human exposure to Hendra virus
We will work with the Department of Health whenever Hendra virus is confirmed or strongly suspected and there is reason to believe humans are at risk of exposure to the virus.
Hendra virus is not particularly infectious, which means that exposure doesn't always lead to infection and all previous human cases have been associated with close contact to an infected horse.
If infection does occur, the incubation period usually ranges from about 5 to 15 days. Evidence suggests that the virus cannot be passed from one person to another.
The symptoms of infection in a person can include:
- dry cough
- sore throat
- breathing difficulties
- unusual sleepiness and confusion
People at increased risk of infection include:
- equine dentists
- feed delivery merchants
- horse owners
- stud workers
If you are concerned you have been exposed to Hendra virus you should immediately seek medical advice, (GP or local hospital).
Currently there is no cure or specific treatment for infection with Hendra virus. Treatment aims to ease symptoms and reduce the risk of complications while the person or animal recovers.
How to reduce the risk of human infection
Hendra virus is a public health concern and requires careful management.
There are several steps you should take while you are waiting for veterinary confirmation:
- Avoid close contact with infected horses and other horses that have been in contact with them.
- Isolate the suspected horse and relocate your other animals.
- Observe the infected horse from a distance and notify your vet if you notice changes in their condition.
If you must have close contact with the infected horse take the following precautions:
- If you have any cuts or abrasions, ensure they are covered with a water-resistant dressing.
- Use personal protective equipment (PPE), covering hands with gloves, feet with boots, and clothing with overalls.
- Wear a P2 mask (particulate respirator) and safety glasses to protect your face from potential contact with the suspect horse's bodily fluids (saliva, nasal secretions, blood and urine).
- Remove and dispose of PPE carefully.
- Wash your hands carefully with soap or disinfectant after all activities.
Ask your vet for advice about putting on, taking off and safe disposal of PPE.
Ensure P2 masks are fitted correctly to reduce your risk of infection.
For further information on human health and Hendra virus please contact Department of Health Communicable Diseases Section on 1300 651 160.
Flying foxes and Hendra virus
Pteropid bats (flying foxes) are the only known natural host of the virus and are capable of carrying virus without any signs of illness.
Research has suggested that Black flying foxes (FF) (Pteropus alecto) and Spectacled flying foxes (P.conspicillatus) are the primary species associated with past HeV spill-over events in horses and all spill-over events have occurred in the home range of these species.
However sero-surveillance has demonstrated that other species such as Grey-headed flying foxes (P. poliocephalus) and Little Red flying foxes (P. scapulatus) also carry antibodies.
Currently Victoria does not lie within the normal home-range of Black flying foxes and Spectacled flying foxes — however, climate and other changes are seeing bat colonies moving southward. The predominant species in Victoria are Grey-headed flying foxes found in both urban and rural environments.
Horses are the only known species reported to have been infected naturally from Pteropid bats.
The typical range of the black flying fox appears to be have been slowly expanding southwards so horse owners and vets need to be familiar with the signs of Hendra.