Seasonal risks of Kunjin and Hendra: an Update
07-Sep-2011KUNJIN VIRUS
Since February 2011 there have been an increased number of reports of NSW horses displaying unusual nervous signs. Similar cases have also been reported in Victoria and South Australia. Laboratory testing suggests that a majority of cases are due to infection with strains of a virus called Kunjin virus.
Origin of the virus
Kunjin Virus has been in Australia for a long period of time. It is primarily a disease of waterbirds and is carried by mosquitoes. Very occasionally the virus can be transferred from mosquitoes to horses. In the past, this has resulted in mild clinical signs in a very small proportion of affected horses.
Kunjin Virus has been in Australia for a long period of time. It is primarily a disease of waterbirds and is carried by mosquitoes. Very occasionally the virus can be transferred from mosquitoes to horses. In the past, this has resulted in mild clinical signs in a very small proportion of affected horses.
The recent floods and wet weather in large parts of Australia have resulted in large bird breeding events and these weather conditions obviously favour mosquito breeding. It is likely that many horses may be infected but only a small proportion of infected horses will become ill.
Symptoms
Early signs of infection may include depression or mild colic. These initial signs are followed by nervous signs including lack of coordination, high stepping in front, weakness in the hind quarters, muscle twitching and increased sensitivity to touch and sound. In some cases there has been facial paralysis or twitching, especially of the lips. Severely affected horses may fall repeatedly or develop convulsions. Some are unable to rise and some have died.
Treatment
Because this is a viral disease, there is no specific treatment. Supportive care, nursing and treatment with pain relief, broad spectrum antibiotics and anti-inflammatory drugs are used to keep the horses comfortable. In spite of treatment, some horses have died and some have had to be euthanazed.
Preventative measures
Stabling horses during the dawn and dusk periods of mosquito activity and the use of rugs and topical repellents can be used to minimise mosquito contact with the horse.
Blood samples from suspected cases can be tested at the Virology Laboratory at the Elizabeth Macarthur Agricultural Institute, Camden.
Risks as we move into Spring
With fewer mosquitoes over winter the risks from Kunjin infection decreased. Given that there is a large population of birds, probably carrying the new strain of the virus, the risk will increase as we move toward spring and summer, especially if it is a wet year.
It is believed that the horse is a dead-end host, so there has been no evidence of risk to humans from direct contact with horses however staff should always be vigilant with their personal hygiene.
Owners and trainers who notice horses displaying unusual signs should contact their veterinarian.
HENDRA VIRUS
(The following information has been prepared by Equine Veterinarians Australia - the Equine Special Interest Group of the Australian Veterinary Association)
The recent cases of Hendra virus in Queensland and NSW have generated concern for everyone associated with the horse industry. It’s important for everyone to understand the basics, and how to protect themselves and their horses from Hendra virus, and also to understand how and why this disease is different to EI.
The basics
Hendra virus can occasionally spread from flying foxes to horses. This is an unusual event, and the circumstances that allow the spread from flying fox to horse are not fully understood.
Once a horse becomes affected with Hendra, the death rate is very high. Clinical signs are VARIABLE and can include high temperature, depression, nasal discharge, problems breathing and in-coordination. The horses rapidly deteriorate within a short period of time(few days).
Hendra virus is not very contagious, and it requires very close contact between a Hendra affected horse and a healthy horse, or a Hendra affected horse and a human, for the virus to be transferred.
If a human contracts Hendra virus, it is most likely that they will become very sick, and death is a real possibility, even with treatment.
There has been no incidence of Hendra in the Hunter Valley.
Horse movements
Because Hendra is not highly contagious, it does not spread from farm to farm. Although it is extremely concerning that there has been a cluster of Hendra positive horses in recent months, there is no evidence to suggest Hendra is spreading from farm to farm; all of these cases are isolated events.
This is completely different from Equine Influenza (EI), which is a highly contagious disease. EI spreads rapidly from horse to horse and farm to farm. This is why it was necessary in 2007 to halt horse movement across NSW and Queensland to try to contain the spread of EI. EI has been eradicated from Australia and is a completely different virus to Hendra.
Because Hendra is not very contagious, there is no need to halt horse movement in NSW or Queensland. There are no plans to restrict horse movement, other than on quarantined farms where the disease has occurred.
There is a Hendra horse vaccine being developed but it will not be ready for release until 2012 or 2013.
Contact your veterinarian quickly if your horse appears ill, and limit contact with sick horses until a veterinarian can assess the horse.
Minimising the Risk of Hendra for yourself and your horse
(Reproduced with the permission of Dr David Lovell, B.V.Sc., M.A.C.V.SC., Q.D.A.H., G.C.M. Redlands Vet Clinic, Qld)
1. WEAR DISPOSABLE GLOVES. Always have a box of disposable gloves on hand. Wear them if doing anything with a horse that involves contact with horse body fluids. THIS IS IMPORTANT.
2. WEAR Personal Protective Equipment (PPE) IF IN ANY DOUBT. Do not, in any circumstances, approach or attempt to do anything potentially invasive with any suspect horse without adequate PPE. Leave it to the Experts. [PPE can be purchased from Scone Equine Hospital - please contact the pharmacist for further information]
3. WASH YOUR HANDS AND EQUIPMENT. A most important factor. Strict personal hygiene is the key component in avoiding infection. Wash hands and equipment and use disinfectant.
4. TPR YOUR HORSE DAILY. Any deviation in the horse’s temperature, heart rate, or respiration is something all owners’ should know and is a primary indicator of the horse’s health.
5. CLINICALLY ASSESS YOUR HORSE. Owners know their horse and intuitively will pick when the horse is not himself. Investigate thoroughly any changes in signs, symptoms or behaviour.
6. RISK ANALYSIS. Always assess the situation and circumstances surrounding yourself and your horse and make a judgement as to the possible risk of a problem.
7. MAINTAIN A “PERIMETER” AROUND YOUR PROPERTY. Maintain a perimeter so that horses across the fence cannot contact each other.
8. “QUARANTINE” ANY NEW HORSES. A critical issue. Remember the incubation period (5-16 days) where an infected horse can appear normal. Isolate any new horses that arrive at your property.
9. STABLE HORSES or HOLD in “SAFE” YARDS at NIGHT if possible when flying foxes are most active.
10. IDENTIFY ALL PLANTS AND TREES. Know whether the trees on your property are food sources for flying foxes.
11. ELIMINATE FLYING FOX FOOD SOURCES. If you cannot remove dangerous plants or trees, at least fence them off or prevent your horse having any access. Make sure that food sources attractive to flying foxes such as fruit and vegetables are not left around horses.
12. FEED & WATER HORSES IN OPEN SPACES or INDOORS. Do not feed or water horses near any possible site where Flying Foxes may feed, roost, or perch
QLD and NSW Outbreaks: The Latest as at 30 August 2011:
There have now been 21 confirmed cases of Hendra virus infection in horses in Queensland (eleven cases on nine properties) and New South Wales (ten cases on eight properties). One dog on one of the Queensland properties tested positive although it showed no signs of disease. Each of this year's fifteen incidents are attributed to different groups of flying foxes and the infections are not being spread from property to property.
The number of locations in Queensland with confirmed cases of Hendra virus this year is nine.
- The number of confirmed horse deaths from Hendra virus in Queensland this year is eleven.
- There are currently five properties in Queensland under quarantine in the Kuranda, Chinchilla and Gold Coast hinterland areas.
- In NSW, a tenth horse was confirmed dead from Hendra virus on 30 August at a property near Ballina.
- On 17 August it was confirmed that a sixth horse in NSW has died from Hendra virus at a property near Ballina, and on 18 August three more horses were reported as confirmed Hendra cases - two on a new property near Ballina, and one on a new property at Mullumbimby.
- A Hendra case in a horse was confirmed near Wollongbar in New South Wales on Friday 1 July. The companion horse on this property subsequently showed clinical signs, was euthanased and confirmed as a Hendra case on 13 July.
- A second NSW property had a confirmed case that was reported on 7 July in Macksville on the mid-north coast. This is the southernmost case that has been reported.
- A third incident of Hendra virus infection in a horse was confirmed on 16 July on a property near Lismore and a fifth horse died from Hendra virus at a property near Mullumbimby on 27 July.
All properties have been placed in quarantine and the dead horses have been buried. Horse and companion animal movements on and off quarantined properties are not permitted
More information at:
• Australian Veterinary Association website
• Qld Dept Primary Industry website
