Hendra Virus

Hendra Virus was first identified in 1994 and has only been found in Australia. It occurs naturally in flying fox populations in all states, and it’s thought to be transferred to horses through contaminated urine, faeces or foetal fluids. Humans become infected through close contact with infected horses. There’s been no evidence of direct infection from flying foxes to humans or of human-to-human infection. Horses can infect other horses as well as humans.

It’s very similar to Nipah virus, another disease originating from flying foxes in Malaysia. Nipah virus has been transferred to pigs and then to humans, and has killed around 200 people in Malaysia, India and Bangladesh.

The clinical signs of Hendra virus in horses are generally respiratory or neurological but can also cause colic and other general signs of illness. Around 70% of horses that have tested positive have died from the disease. Those that recovered have been euthanased (compulsory government regulation). There have been seven known cases in humans, with four fatalities. The human cases have come from close handling of infected horses.

Hendra virus is now an endemic disease in Australia. All known cases in horses (more than 90) have occurred in Queensland or northern NSW from the Great Dividing Range east. However there is a potential for disease wherever there are flying foxes given that antibodies to the virus have been detected in some proportion of all Australian flying fox populations in all states.

There is a 50% mortality rate in humans for Hendra, and all surviving humans have ongoing serious health complications

  • The natural host for Hendra virus is the flying fox.

  • It is not clear how horses become infected, but it may be by eating food contaminated by bat urine or birthing products.

  • Human infections have occurred as a result of direct exposure to body substances from infected or dead horses.

  • To date there has been no known transfer of Hendra from person to person or from flying foxes to other animals apart from horses.

  • Species known to be infected with the virus include

    • Horses

    • Humans

    • Dogs

    • Under laboratory conditions – cats, pigs, guinea pigs and ferrets

    • There is a legal requirement that any non-human animal that tests positive for Hendra Virus infection must be euthanased regardless of illness or recovery

The potential seriousness of Hendra virus infection for both humans and horses requires that workplace health and safety measures, to prevent infection, should be implemented at workplaces where there is occupational contact with horses. Sound hygiene and biosecurity measures should be adopted as a routine practice for all horse contact. Information on these measures can be found on the NSW DPI website as well as a lot of useful information being available on the QLD Biosecurity website.

Hendra virus is a notifiable disease. If you suspect a notifiable disease, whether you are a horse owner, a veterinarian, laboratory staff or anyone else, you must report it to NSW DPI or the Emergency Animal Disease Watch Hotline on 1800 675 888.

Reducing Hendra risk 

The AVA recommends that all horses should be vaccinated against the Hendra virus.

Based on the current understanding of the spread of Hendra virus infection there are a number of strategies that can be employed by horse owners to reduce the risk of transmission of the virus.

  • Place all feed and water containers under cover to reduce contamination from flying foxes

  • Try to bring horses into covered enclosures or enclosed paddocks with no trees at night to reduce potential contact with flying fox colonies.

  • Remove horses from paddocks where trees attract flying foxes or fence off trees to prevent horses grazing underneath.

  • When planting trees on your property do not plant trees that attract flying foxes in or near horse paddocks. These include trees with soft fruits for example, figs and stone fruits such as peaches, loquats, and mangos.

  • Seek veterinary advice before bringing any sick horses on to your property.

  • If you have a horse that you suspect of having Hendra, do not move any other horse off the property until given the all clear by the proper authorities.

  • Keep any sick horses isolated from people and other animals.

  • Plan a quarantine area on your property where sick horses can be isolated.

  • Remember to thoroughly wash your hands after and between handling individual horses to prevent the potential spread of Hendra virus infection.

Hendra vaccine

The Equivac® HeV vaccine was made available to horse owners 1 November 2012.

The Australian Veterinary Association says that although the vaccine will significantly decrease the risk of exposure to the Hendra virus for horse owners, handlers and veterinarians, precautions still need to be taken.

It is recommended that all horses are vaccinated against Hendra Virus, not only for their protection but also the protection of people and other animals interacting with the horses.

To date the confirmed side effects include transient fever and occasional swelling. These are the same side effects seen with most vaccinations including the Tetanus vaccine. Over 380,000 doses have administered with an adverse reaction rate (ie fever etc) of approx. 0.002%. Compare this to the greater than 50% death rate in humans and 100% compulsory euthanasia in horses testing positive for the disease

The Australian Pesticides & Veterinary Medicine Association (Regulator) has no confirmed cases of more serious side effects.

The vaccine is currently registered to be given as 2 initial injections 4-6 weeks apart with a booster at 6 months. After the initial injections, boosters are given annually.

Why Vaccinate on the South Coast?

Although there haven’t been any confirmed cases of Hendra Virus in this area, flying foxes from our region have tested ‘sero-positive’ to the virus. This doesn’t mean the local flying foxes are carrying the virus, but it does mean that they have been exposed to it.

Where there are flying foxes that have been exposed to Hendra Virus there is the potential for disease transfer to horses and then on to humans. The large numbers of flying foxes that visit Panboola Wetlands each autumn do present a risk if coming into contact with horses or their water and feed sources