Urban sprawl could increase Hendra risk

Australia's urban sprawl could see more people exposed to the Hendra virus via bats. (AAP)

When people settle in new areas bat colonies follow, sparking fears urban sprawl could see more people exposed to the Hendra virus.

Urban sprawl could see more Australians exposed to the deadly Hendra virus, a new study suggests.

Australian researchers have found that as humans settle in new areas, bat colonies move in too.

And that means more people could be at greater risk of exposure to the virus, which bats carry and shed, infecting horses, which can in turn infect people.

Michael Walsh, from the University of Sydney, led a study that mapped human population changes over three decades and found that as people settled in new locations and established gardens with fruit trees and other vegetation bats like, colonies followed them.

He says that could see Hendra emerge well beyond southeast Queensland and northeastern NSW, where the virus is typically seen, to cities including Sydney and its surrounds.

"What we found was that as the human populations changed, it was followed by subsequent changes in bat populations," Dr Walsh told AAP.

"The concern is that as we create more favourable habitats for the black flying fox with urban sprawl, and as we degrade their natural habitat, is the population of black flying foxes going to become more and more established in and around Sydney?

"That's certainly a possibility and even further south than Sydney too."

Dr Walsh says the destruction of natural bat habitat is at the root of the problem and the study shows the importance of conserving it, particularly for the black flying fox which sheds the virus readily and is found in the existing Hendra zone, but is not yet common in places like Sydney.

He's warned against culling bats or trying to shoo away problem colonies, as some Queensland towns have tried to do, because stressed bats shed more of the virus.

"You can think of the bat population as being a mega-community, made up of smaller, individual populations. These bats migrate back and forth and they need to be able to do that freely.

"When they can do that, it means the overall broader bat population is much healthier and we don't see these significant spikes in Hendra epidemics."

Seven people have been infected with Hendra since it emerged in the Brisbane suburb of the same name in 1994. Four of them, including two vets, died.

So far there have been 60 known outbreaks resulting in the deaths of 102 horses, all in Australia's north-eastern coastal region.

The study involved researchers from the University of Sydney, University of Melbourne and the State University of New York and has been published in the journal Scientific Reports.


* Fruit bats host the virus

* Infected bats excrete the virus in their urine, faeces and saliva

* Bats can infect horses, which can in turn infect other horses, and people

* There's no documented cases of direct bat-to-human transmission

* The virus commonly hits the respiratory system

* It can also affect the brain, leading to convulsions and/or coma

* In 2016, researchers said a year-long trial of a human vaccine showed no negative effects

* A vaccine for horses has been available since 2012

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