Providing practical information to help you protect your farm from biosecurity risks

Horses versus mosquitoes and bats

June 3, 2011

Horse drinking from damAustralian horse owners are facing a ‘mystery’ neurological virus affecting animals from Western Australia to Queensland.

From the outset suspected to be a mosquito-borne arbovirus, laboratory testing has revealed the cause as a combination of three diseases: Kunjin virus, Murray Valley encephalitis and Ross River virus, with the first of these responsible for most cases.

An estimated 246 cases have been reported this year, of which 22 horses have died.

Roger Lavelle, President of the Australian Horse Industry Council, was satisfied with the way Australia’s animal health system responded to the issue.

Mr Lavelle praised the early information sharing because it “kept everybody abreast of what’s happening, especially since a lot of people from industry, including myself, are not up to speed with the latest developments. It was really helpful in explaining how difficult it was to identify what’s caused the problem in some of these horses,” he said.

Even though mosquito numbers have decreased in some areas due to cooler weather, and the number of reported cases has plummeted, horse owners are urged not to become complacent.

Owners should try to prevent their animals from being bitten by insects through simple biosecurity practices including rugging, fly masks and using registered insect repellents. Ensuring that horses are kept in good condition will help build a strong immune system and minimise the risk of infection with arboviruses.

Hendra virus vaccine on its way

CSIRO scientists have shown that a new experimental vaccine helps to protect horses against the deadly Hendra virus. Dr Deborah Middleton, from CSIRO’s Australian Animal Health Laboratory, announced the successful progress to develop the vaccine, saying that trials so far have shown that it prevents the infection of horses with Hendra virus.

“A horse vaccine is crucial to breaking the cycle of Hendra virus transmission from flying foxes to horses and then to people, as it prevents both the horse developing the disease and passing it on,” Dr Middleton said.

Since it first appeared in 1994, the deadly Hendra virus has been confirmed in 40 horses and seven humans. Five of the 14 known outbreaks have spread to people; all horses either died or were destroyed and four of the people died.

Hendra virus is carried and transmitted by flying foxes, especially in the northern half of Australia. As there is currently no specific treatment for Hendra, it is extremely important to implement the following simple preventive measures in risk-prone areas:

  • It is strongly advised that you avoid contact with sick horses and their blood and body fluids until a veterinarian has excluded Hendra virus infection as the cause of illness.
  • If contact with a sick horse is absolutely unavoidable, you should seek advice from your veterinarian about appropriate personal protective equipment such as gloves, protective eyewear and a face mask.
  • If you have had contact with sick horses, shower with soap, wash your hair and put on clean clothes and footwear before handling other horses.
  • Remove any clothing contaminated with body fluids from a sick horse carefully to ensure there is no contact with your facial area, particularly your eyes, mouth and nose.
  • After handling any horse, wash your hands with soap and water and dry, or use hand wipes and waterless hand hygiene solution.
  • Place horse feed and water containers under cover if possible.
  • Do not place horse feed and water containers under trees, particularly if flying foxes are attracted to those trees.
  • Do not use feed that might be attractive to flying foxes if they are known to be in the area. Fruit and vegetables (eg apples, carrots) or anything sweet (eg molasses) may attract flying foxes.
  • If possible, remove horses from paddocks where flowering or fruiting trees have resulted in a temporary surge in flying fox numbers. Return the horses after the trees have stopped flowering or fruiting.
  • If it is not possible to remove horses from paddocks, try to temporarily remove your horses during times of peak flying fox activity (usually at dusk and during the night).
  • Keep any sick horse isolated from other horses, people and animals until you have obtained a veterinarian’s opinion.
  • Do not allow visiting horse practitioners (farriers etc) to work on sick horses. They should only work on healthy horses. If there is more than one horse on your property, handle unaffected horses first and then only handle sick horses after taking appropriate precautions.
  • Make sure gear exposed to any body fluids from horses is cleaned and disinfected before it is used on another horse. This includes things like halters, lead ropes and twitches. Talk to your vet about cleaning agents and disinfectants to use.
  • Seek veterinary advice before bringing any sick horse onto your property.
  • Do not take sick horses to events such as competitions or pony club.

For comprehensive information on the Hendra virus, visit the Queensland Department of Primary Industries and Fisheries’ web page.