Since late June eight horses have died from the Hendra virus and dozens of people who made contact with sick horses are now being tested. While rare in humans, the few known cases of Hendra infections have seen people unwell with influenza-like illness, occasionally progressing to high fever, convulsions and death.
Today’s Cairns Post front page
Experts say there are still major gaps in their knowledge of the spread and transmission of the virus, but are warning horse owners and the public to be vigilant and understand what they can do to limit the outbreak. Crikey spoke to Australian Veterinary Association president Barry Smith for clarification …
How does Hendra spread?
Fruit bats are the natural hosts of Hendra, so the virus is carried by the bats but has little effect on them. We know the bats pass the virus through their bodily secretions; so any feces, saliva or bodily fluids they excrete could potentially be carrying Hendra. Horses usually pick up Hendra by ingesting infected material or breathing it in by a droplet. From there, the virus can be present in the horse for several days before they show any signs of illness, and that is the real problem. Horses can be excreting the virus for days before it becomes obvious they are infected. People then contract the virus in much the same way horses do, by coming in contact with excretion or breathing it in in by a droplet.
Are we in control of Hendra?
That’s a good question. At this point it’s hard to give a definitive answer. Up until this year we would have had a different story to tell, but the recent outbreak of the virus has been unprecedented.
There seems to have been a change in the way the virus spreads; for some reason it has changed, and at this point we don’t know why. There are still a lot of gaps in our knowledge.
Is a bat cull the best way to contain the virus?
Flying foxes are a very mobile animal, and they fly all across Australia. We know that from north-west Queensland they can fly to Papua New Guinea, so it would be extraordinarily difficult to attempt a cull, and once a local population of bats is taken out there is nothing to stop new bats flying back in. Furthermore bats are important to pollination of plants and there would be a significant ecological cost to destroying bat populations.
How can we contain the spread of the virus?
Because we can’t control where and how far bats fly it is almost impossible to contain Hendra. Some time next year we may have a vaccine available for horses, but there is still a lot of work to do on that front.
How much risk does Hendra pose to those outside the horse industry in NSW and Queensland?
It is important people are made aware that the virus is out there and it is a risk. At the moment there have only been spillovers into Queensland and NSW, but due to the wide movements of fruit bats there is a possibility the virus could spread to other areas.
What can we do to minimise the risk of contracting Hendra?
At this point we need people to watch their personal hygiene and be careful around horses. Horse owners should look at getting a vet to check out any sick horses and do a risk assessment of their stock. The season for Hendra infections usually lasts from May to November, so there is still a long way to go in the season and people need to be vigilant.
No we do not have handle on this virus, I expect the idea of a season for potential infection will be abandoned in time. I have considered how horse owners and people supplying paddocks may suspend some sort of plastic canopy over their drinking water supply troughs for horses so that droppings and the visits of bats are minimized or prevented. Understanding as I do that horses will learn or can be trained to move such a devise aside to access drinking water.
As an owner of many horses, I find the calls for culling bats to be completely ridiculous.
Maybe it is just another media beat up to find the most hysterical media talent for a headline comment.
Horse owners have to take responsibility for maintaining the health of their animals by using good biosecurity in times of high risk. For all livestock diseases. If they couldn’t be bother installing covered water troughs and feeding areas AWAY from roosting areas you have to wonder how conscientious they are with just the basic health & welfare equine management.
After all, owning horses is a completely optional pastime. If they keep agitating I think they will find that in terms of effective disease control, it would be much easier and cheaper to remove horses from high risk areas.
That said, every horse owner also knows that no matter what you do, sometimes shit happens. So hopefully a vaccine will be available soon. That will really sort the conscientious owners out from the whingers.
Should add -Dr David Lovell from Redlands Vet Clinic offer the most practical advice;
THERE ARE 3 ELEMENTS TO THE CONTROL OF HENDRA
(1) Prevent contact between fruit bats and horses
(2) Monitor your horse carefully
(3) Maintain rigorous personal hygiene
12 STEPS TO “HENDRA PROOF” YOURSELF AND YOUR HORSE
(1) 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
(2) MAINTAIN A “PERIMETER” AROUND YOUR PROPERTY You go to all the trouble to protect yourself and your horse. Do not rely on your neighbour to do the same. Maintain a perimeter so that horses across the fence cannot contact each other
(3) “QUARANTINE” ANY NEW HORSES A critical issue. Remember the incubation period where an infected horse can appear normal. Isolate any new horses that arrive at your property. Most important for spelling breeding and training farms
(4) IDENTIFY ALL PLANTS AND TREES Know the identity of all plants and trees on your property and whether they are likely to be potential food sources for bats
(5) ELIMINATE FRUIT BAT FOOD SOURCES If you cannot remove dangerous plants or trees, at least fence them off or prevent your horse having any access
(6) FEED & WATER HORSES IN OPEN SPACES or INDOORS Do not feed or water horses near any possible site where bats may feed, roost, or perch
(7) STABLE HORSES or HOLD in “SAFE” YARDS at NIGHT Bats are most active at night. Ideally do not allow horses outside where bats may be traversing or feeding
(8) TPR YOUR HORSE DAILY So easy and such a basic monitor of your horses health. Any deviation in the horse’s temperature, heart rate, or respiration is something all owner’s should know and is a primary indicator of the horse’s health
(9) CLINICALLY ASSESS YOUR HORSE Owners know their horse and intuitively will pick when the horse is not themself. Investigate thoroughly any changes in signs, symptoms or behaviour
(10) WASH YOUR HANDS The most important factor of all. Strict personal hygiene is the key component in avoiding infection
(11) WEAR DISPOSABLE GLOVES Always have a box of disposable gloves on hand. Wear them if doing anything with a horse that involves contact with body fluids
(12) WEAR PPE IF IN ANY DOUBT Do not, in any circumstances, approach or attempt to do anything potentially invasive with any suspect horse without adequate personal protection equipment. Leave it to the experts
Clearly, a vaccine for horses is the solution. But sometimes developing a vaccine against a virus can take time, although Hendra is an enveloped virus so it should eventually succeed. BUT what is so typically Australian is that funding for this job has been miserly. It is now 17 years since the first outbreak. The CSIRO/DPI scientists have complained about discontinuity of funding in the past –but probably now are constrained by management about speaking about it.
Although technically the infection route is undetermined, almost certainly it is via inhalation–“probably” for horses but much more certainly for humans (in the field; in autopsies or needle-stick it is direct infection in the bloodstream which is possibly less fatal). This means prevention in humans is really not so difficult. It should be noted that the last vet who was infected and died, by his own admission did not adhere to the prescribed precaution (facemask) while attending a sick horse. If I remember correctly he said that it was not until he had reached the animal that he realized he had left his facemasks in his car which was some hundred metres away. He paid a terrible price.
I do not know if this means all people dealing with horses should wear a facemask 100% of the time, but I know what I would do…… (and the mortality rate has been extremely high in Queensland, much more than “occasionally progressing to high fever, convulsions and death”, closer to 75%).