What is Hendra Virus?
The natural host for Hendra Virus is the flying fox (fruit bat). On rare occasions, Hendra Virus can pass from flying foxes to horses, causing severe illness, usually resulting in death.
Hendra Virus is a zoonotic disease; that is the disease can be transmitted from horses to humans during close contact with an infected horse.
Hendra Virus is a notifiable disease in Australia. It is a rare disease and has only been detected in Queensland and Northern NSW. However, the death rate related to infection is very high – about 50% in humans and more than 70% in horses.
What is the risk in Victoria?
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, and/or with horses arriving in Victoria from Queensland or Northern NSW.
Protecting horse feed and water from contamination by flying foxes, early isolation of a sick horse while awaiting veterinary attention, and good hygiene and cleaning practices are all important.
Why is Hendra virus considered low risk in Victoria?
Hendra virus disease has never been identified in Victoria, despite our best efforts to detect it since its first occurrence in Queensland in 1994. Regular monitoring and testing aimed at finding the disease in horses showing Hendra-like signs has continually been negative Other routine monitoring activities (e.g. testing horses for export) and targeted activities (e.g. knackery surveillance) have also provided supporting evidence of the ongoing absence of Hendra virus in the Victorian horse population.
In addition, the virus has not been isolated from samples obtained from flying foxes in Victoria, although serological evidence indicates that a percentage of the flying fox population has been exposed to the virus.
There are clear differences in epidemiological conditions between Victoria (where the disease has not occurred) and coastal Queensland/ northern NSW (where occurrence has been sporadic). Flying fox populations in Victoria are smaller and less numerous, and the opportunities for transmission are fewer. The apparent high level of exposure required for transmission from bats to horses does not occur in Victoria.
The normal range of the flying fox species most closely associated with Hendra virus outbreaks, the black flying fox, does not extend to Victoria. Notably, all confirmed cases of Hendra infection in horses and people, to date, have occurred in the typical range of the black flying fox (see map). Cases have only occurred within a small part of the range of the grey headed flying fox (the prevalent flying fox species in Victoria): that part in Queensland/northern NSW which it shares with the black flying fox.
Monitoring and testing strongly suggest that Victoria is free from endemic Hendra virus disease in horses, and transmission from local flying fox populations to horses is considered highly unlikely. However, it would be a mistake to assume that the disease will never be diagnosed here. The horse population in Australia is highly mobile, and it is not impossible that a horse that is incubating Hendra virus disease could be transported from Queensland or northern New South Wales to Victoria. In addition, the typical range of the black flying fox appears to be have been slowly expanding southwards over past several decades. It is, therefore, important that vigilance be maintained.
Horse owners and veterinary practitioners need to be familiar with the signs of Hendra, and instigate an investigation when the disease is suspected.
How is Hendra Virus transmitted?
The transmission of Hendra Virus from flying foxes to horses is not yet fully understood. However, there is no evidence of bat-to-human, human-to-human or human-to-horse transmission of Hendra Virus.
Hendra Virus has not been shown to be highly contagious; however, human cases of infection have been linked directly with exposure to the virus during autopsy of an infected horse or from close contact with an infected horse.
Is there a vaccine against Hendra available for horses?
There is a vaccine against Hendra virus available that is fully registered with the Australian Pesticides and Veterinary Medicines Authority, through specially accredited veterinarians. Horse owners moving horses to Queensland or northern New South Wales should consider vaccination, as well as horses from these areas that are to be introduced to Victoria. More information on the vaccine is available from the manufacturer at Health4horses and the APVMA.
What to do if you suspect HeV in your horse?
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, and/or your horse has traveled from Queensland or Northern NSW in the past 2-3 weeks you should contact your veterinary practitioner or the Emergency Animal Disease Hotline on 1800 675 888.
How do I reduce the risk of becoming infected?
Hendra virus is a public health concern and can create substantial workplace health and safety issues. It requires careful management.
There are several steps you should take while you are waiting for veterinary confirmation of Hendra virus:
- Avoid close contact with suspect infected horse/s and other horses that have been in contact with them
- Isolate the suspected horse where possible—preferably by relocating other animals
- Observe suspect horse from a distance and notify your veterinarian if you notice changes in their condition
- Where possible, provide feed and water for the suspect horse/s from a distance
- If close contact with the suspect horse is necessary ensure you 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. This should help 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/disinfectant after all activities
Ask your veterinarian for help with putting on, taking off and safe disposal of PPE. Ensure P2 masks are fitted correctly to reduce your risk of infection.
What happens if my horse is confirmed HeV positive?
If your horse tests positive to HeV your local veterinarian will work with the Department of Economic Development, Jobs, Transport and Resources (DEDJTR) to manage the situation.
The property where the horse is located will be placed under quarantine by DEDJTR until all other horses on the property and that have visited or traveled off/on the property within the last few weeks can be cleared of infection.
Once DEDJTR has sufficient evidence to suggest that no other horses have been infected with HeV, the quarantine will be lifted.
What happens to my HeV positive horse?
It is Australian national policy that all horses confirmed positive, by laboratory testing, for HeV are humanely destroyed. This aims to prevent the spread of infection to humans and other animals. For further information on Hendra Virus please contact your local DEDJTR Animal Health Staff on 136 186.
Human exposure to HeV
DEDJTR will work with the Department of Health whenever HeV 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. If infection does occur, the incubation period usually ranges from about five 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 fever, headache, dry cough, sore throat breathing difficulties, dizziness, unusual sleepiness and confusion.
People at increased risk of infection include veterinarians, farriers, equine dentists, strappers, feed delivery merchants, horse owners and stud workers.
Hendra Virus tends to attack either the respiratory system or the nervous system. In Australia, the fatal complications have included:
Septic pneumonia – severe lung infection involving pus, abscesses and destruction of lung tissue
Encephalitis – severe brain inflammation and swelling which can lead to convulsion or coma
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 recovers. There are experimental treatments available for people at high risk for exposure to the virus to prevent infection.
For further information on human health and Hendra Virus please contact Department of Health Communicable Diseases Section on 1300 651 160.