By Heike Hahner
The Hendra virus, according to the Australian Veterinary Association, is one of the world’s rarest diseases and endemic to Australia.
It was first identified in 1994 in Queensland where it killed 14 horses and one person. Since then more than 30 horses have died and also four people who worked in the horse industry.
Twenty years on we know that Hendra virus is shed at particular times, the colder months of the year, in the saliva, urine and foecal matter dropped by flying foxes under their roosting trees. Interestingly, away from the ‘drip zone’ of these trees virtually no evidence of the virus was found.
Flying foxes are nomadic mammals and fly across eastern and northern Australia. They can be found as far south as Melbourne. In 2010, flying foxes were sighted in Orange and as far south-west as Adelaide.
Researchers speculate that flying-foxes are travelling more extensively because of food scarcity, habitat destruction or seasonal variations, and they are uncertain whether such movements will be repeated. Flying foxes will roost in native as well as fruit trees but you will know if they are on your property because of the noise they create.
The Hendra virus reaches humans via horses, not directly. Horses may become infected with the virus by grazing under roosting trees or drinking from water sources placed beneath roosting trees. The virus may reach humans from the body fluids of an ill or dead horse. The mortality rate from Hendra is 50 percent in humans and 70 percent in horses.
Horses, and subsequently the people who care for them, are at highest risk of infection from areas with a high level of flying fox activity. That might mean horses that travel a lot, or horses bought from areas with higher flying fox populations up north.
While some veterinarians are urging universal vaccination, at the moment only some of the Pony Clubs and the Show Societies have compulsory vaccination requirements. Queensland Racing is offering subsidised vaccination to horse owners due to the high cost of the regular vaccination regime. In NSW there is no policy requiring the compulsory vaccination of thoroughbred racehorses against Hendra virus.
The veterinary association stresses that the vaccine will significantly decrease the risk of exposure to the Hendra virus for horse owners, handlers and veterinarians. Meanwhile, the following precautions might help if flying foxes are suspected nearby or horses have recently been in a contagion area.
Place all feed and water containers under cover, and at night bring horses into covered enclosures or enclosed paddocks with no trees.
Avoid planting trees with soft fruits near horse paddocks.
Seek veterinary advice before bringing any sick horses on to your property.
Look up symptoms and get veterinary advice immediately if you are concerned about a sick horse.
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 and keep sick horses isolated until investigated.
The information in this article was sourced from:
Australian Veterinary Association: www.ava.com.au/hendra-virus
Racing Queensland: www.racingqueensland.com.au
Racing NSW: www.racingnsw.com.au
Australian Stock Horse Society: www.ashs.com.au/news/hendra.asp