Hendra virus infection Industry participants are reminded to be vigilant about the Hendra virus and the need for preventative measures to minimise the risk of infection of horses, humans and companion animals.
Hendra virus infection is a disease of horses and humans that can cause a serious and life threatening illness. The natural hosts of Hendra virus are fruit bats (flying foxes) which can then pass the virus onto horses. Human infection results from close contact with the blood, body fluids and tissues of infected horses. There is no evidence to date of human-to-human or bat-to-human spread of Hendra virus. However, there is evidence of horse-to-horse infection due to contact with the secretions of sick horses.
Hendra virus infection of horses is characterised by the rapid onset of illness, with increased temperature, increased heart rate, discomfort or weight shifting between legs, depression, respiratory and neurological signs. Not all of these signs will be found in any one infected horse.
Key signs in horses: • acute onset of illness • increased body temperature • increased heart rate • discomfort/ weight shifting between legs • depression • rapid deterioration
Other respiratory signs: • respiratory distress—increased respiratory rates • terminal nasal discharge—can be initially clear, watery discharge progressing to stable white froth and/or stable blood-stained froth
Other neurological signs: • ‘wobbly gait’ progressing to loss of control of muscle movement • altered consciousness—apparent loss of vision in one or both eyes, aimless walking in a dazed state • head tilting, circling • muscle twitching • urinary incontinence • lying down with inability to get up • terminal weakness, loss of control of muscle movement and collapse
Protection of horses The risk of Hendra virus infection in horses is higher in those situations where horses are kept outdoors in areas where flying foxes are known to inhabit. Flying foxes often visit properties where native eucalypts, bottlebrushes, lilli-pillies, figs and melaleucas are flowering. Blossoms are their primary source of food. They will also feed on palm seeds and exotic fruits when native food is less abundant.
Horse owners/trainers should follow these steps to protect their horses:
• Place feed and water containers under cover if possible • Do not place 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 (e.g. apples, carrots) or anything sweet (e.g. 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 removal of horses from paddocks is not possible, restrict their access to the areas where the flying foxes are active and for the period of time they are present (e.g., by fencing off trees where the animals roost or where they gather while flowers and fruit are present). • Particularly in high risk areas, vaccination of horses should be considered.
Racehorses returning from spelling properties Horses returning to a racing stable from a spelling property, particularly any located in coastal northern NSW or Queensland, potentially pose a greater Hendra infection risk than horses already in the stable. Trainers should ascertain the level of risk of Hendra virus infection at the spelling properties from which their horses are returning to their racing stable, and to check their vaccination status.
As a precaution, horses arriving at a racing stable from a spelling property, particularly those in coastal northern NSW and Queensland, and from racing stables in northern coastal NSW and Queensland after the Brisbane, Grafton and Coffs Harbour carnivals, for example, should undergo a period of isolation in the stable, where they can be kept physically separate from the other horses for at least 2 weeks after arrival. During this time, a high level of basic hygiene should be practised by stable staff handling these horses. Also, these horses should be closely monitored for any signs of illness, including at least daily temperature checks. It is important that staff be alert to any deviation from normal behaviour and demeanour in these new arrivals.
This is in addition to good biosecurity practice of monitoring closely all horses in a racing stable, including the taking of the temperature of each horse on a daily basis before the horse goes on to the training track or travels to the racetrack for competition.
Under no circumstances should a horse with an elevated temperature or showing signs of illness be permitted to go on the training track or to travel to a racetrack for the purpose of trialling or competition.
Trainers are reminded of Australian Rule of Racing 64K and the requirement to notify the Stewards if a notifiable disease such as Hendra virus infection is suspected in a training establishment.
Safety precautions as Hendra virus can be fatal to humans Human infection is thought to occur through contact with body fluids of infected horses.
Maintain a high level of routine stable hygiene, including covering any cuts or abrasions on exposed skin before handling horses, for example by using disposable gloves, and washing hands well with soap and water, especially after handling your horse's mouth or nose (eg fitting or removing a bridle) and before eating, smoking or touching your eyes, nose or mouth.
The risk of human infection can be greatly reduced by adopting good hygiene practices as a matter of routine and taking increased precautions around any sick horse.
It is important to minimise contact with any horse if it is unwell. Trainers and owners should contact their vet immediately if they notice health problems in their horses or suspect Hendra infection. As a precaution, people in close contact with horses that have Hendra-like signs should wear protective face masks, goggles and gloves and take care with personal disinfection.
Vaccination While there is no current policy in NSW requiring the compulsory vaccination of thoroughbred racehorses against Hendra virus, it is acknowledged that thoroughbreds are vaccinated, particularly in susceptible areas of the state such as the north and mid north coast.
According to animal health authorities including the NSW DPI, vaccination is an effective way of reducing the risk of Hendra virus infection in horses and therefore human infection.
The Hendra virus vaccine is registered with the APVMA and is available for administration by veterinarians. Annual booster doses are required after the initial primary course and first 6-month booster dose.
Trainers are reminded that a horse that has been vaccinated against Hendra virus is not permitted to start in any race for five clear days from the day of the dose of vaccine (AR64N). Further, trainers must ensure that a record of the Hendra virus vaccination is included in the trainer’s record of treatment for such horse in accordance with the requirements of AR178(F)(1).
Further information and resources on Hendra virus are available at the NSW DPI website at Hendra virus - General information (DPI)
To report suspicions of Hendra virus infection, contact your vet or ring the emergency animal disease hotline on 1800 675 888. Racing NSW Stewards must also be notified on 02 9551 7500.