Monday, 1 August 2011

Hendra Virus Makes Some People Batty

Queensland's media and politicians are currently in a tizz about what is being referred to as an outbreak of Hendra Virus.  For those outside Queensland who may not have been following this story, Hendra virus primarily occurs in populations of flying foxes, giant fruit-eating bats of the genus pteropus.  However, from time to time it also spills over to infect horses and, via them, humans.  Its name comes from the suburb of Brisbane where our main racetracks are located, and where it was first detected in 1994, taking the life of horse trainer Vic Rail and a number of horses.  This is where it gets emotional.

To some extent, the emotions are understandable.  Australians love their horses, and Hendra virus has been fatal to every one of the 50-odd horses known to have contracted it since 1994.  It's also very dangerous to humans, having led to the death of four out of the seven humans known to have contracted it.  This winter there have been more horses infected than ever before - properties in eight locations in Queensland are affected and ten horses and one dog have died so far, although no humans have yet tested positive.

Still, the scale of the problem seems to suggest a moderate response is most appropriate.  The distribution of the outbreaks suggests that this is not a spreading epidemic (except perhaps amongst the bats) so much as a series of incidents.  After all, ten horses is not that many.  Queensland Health and Biosecurity Queensland have control and testing procedures in place, and the State Government has allocated $6m to further research on the disease. 

Still, this is not enough for some people, and a number of local communities are demanding that their flying fox colonies be "moved on".  Queensland's pretend Opposition Leader Campbell Newman, who could well be Premier by this time next year, has promised to do just that.  I don't think Mr Newman has really thought this one through, so let me help him.

Flying foxes are highly sociable creatures and spend their day in huge colonies, with thousands of bats roosting side by side in trees.  At night they fan out in twos and threes, searching for fruit and flowers, and flying up to 50 km each night.  As drought and deforestation have taken their toll, more groups have set up camp in or near urban areas, where flowering plants are readily available.  Aside from the very occasional Hendra virus issue they are not really dangerous to humans, but they stink and make a lot of noise, so you wouldn't necessarily want to live too close. 

It's these that Mr Newman is promising to move on.  However, there are a number of problems with this.  First of all, colonies are not that easy to move.  Basically, you need to prevent them from roosting in their chosen locations.  This means you need to go out to their nesting sites in the early hours of the morning, making loud noises and perhaps setting off smoke bombs, to scare them away.  Bats are not strong in the intellectual department so you need to repeat this procedure quite a few times before they get the message.

All this is theoretically possible, but why would you?  The flying foxes thus scared away will, of course, roost somewhere else, most likely nearby.  From their new location, they will once again fly their 50km each night, spreading their viruses over much the same territory as they did before.  However, because they are more stressed, they will be more vulnerable to catching the disease and will excrete more.  In other words, you won't get rid of them but you will increase the chances of infection.

From here you can only sink further into absurdity.  To really remove the problem in a particular community, you will need to remove the creatures beyond their 50km limit.  If it is not your intention to kill them, you will need to select your new location carefully - somewhere with lots of flowering plants and no horses.  Off the top of my head I would think such locations were fairly rare.  Then of course, assuming you can find such a location, you would have to somehow get the flying foxes to it.  Option A - herding them - would seem a little impractical given that they don't fly in flocks and that any attempt to drive them in a particular direction will just scatter them.  Not to mention that they sleep during the day, so you would have to herd them at night. Option B - catching them and transporting them in cages - is also slightly comical.  Did I mention that they roost in trees, and can fly?  In addition, they have sharp teeth and as well as Hendra virus they carry another deadly disease known as bat lyssavirus which humans can catch by being bitten or scratched.  I guarantee that if you try to catch a flying fox, it will bite and scratch you.

So it would seem that the only option left to Mr Newman will then be to "cull" the bats, a handy euphemism for killing them.  Hopefully even Campbell Newman will consider this a little drastic, especially given that flying foxes are the chief agents for propogating various plant and tree species, spreading them in their faeces as they fly over their 50 km territories.  The destruction of not only our most prominent native bat, but our open forest ecosystems, would seem to be a huge price to pay to spare the lives of a dozen horses.

Still, it's something to keep up our sleeves for when the eventual US or European debt default sparks the next global financial crisis.  Governments looking for something to spend fiscal stimulus money on will find that we already have enough school halls.  What better way to spend the money in regional Australia than to employ armies of people to chase flying foxes from place to place?

(Flying Fox photos from Brad and Lynn's Field Photos.)

(And bugger me if he didn't go and do it!)

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