James Cook University (Australia) researchers are hopeful they can develop strategies to manage the transmission of the deadly Hendra virus. The virus originates in bats and is transmitted via horses to humans.
Infection of horses was relatively rare between 1994,
when Hendra was first discovered, and 2005. But since 2006 it has been
happening more frequently and over a wider geographic range.
Gerardo Martin from JCU (pictured above) is part of a team analysing the process and how to disrupt it.
“Bats are host to a disproportionate number of viruses
that can spread to other animals,” he said. “The thinking is that their
unique physiology - a product of their ability to fly - and their
tendency to live in large groups, make them hosts to a high diversity of
viruses without being affected as widely as other mammals”.
The researchers have found a chain of events that
carry the infection from bat to horse, and they believe the process can
only be broken at some of its links.
Dispersing bat colonies, as has been tried in Cairns
and Charters Towers, does not work, as the bats can move elsewhere and
make space for another colony to move in.
Mr Martin said killing or dispersing the animals also
leads to more stress and possibly increasing risk of contact with other
animals or humans. “Anecdotally, after one cull, two hundred injured
bats were found in an orchard, unable to fly,” he said. “Something like
that only increases the likelihood of contact with humans.”
He said there were a lot of unanswered questions about bat behavior and the environmental variables that affected it.
“An example of this is that you have an animal like
the black flying fox extending its range south faster than was
predicted. No-one knows why at this point.”
Mr Martin said he and colleagues including Lee
Skerratt and Raina Plowright were now looking at how long Hendra
survived after bats excreted it and under what conditions.
“For instance, we know UV radiation is a very
effective killing agent; if we find Hendra is gone a few hours after the
sun hits it we could improve preventive strategies.”
The team are also fitting horses with GPS trackers to
monitor their movement and grazing patterns overnight, when flying foxes
feed in paddocks.
Mr Martin said the best strategy to prevent Hendra in
the long term could be a combination of protecting and regenerating the
bats’ native habitats away from human settlement, vaccination of horses,
and preventing horses from grazing under trees where bats feed during
night-time hours.