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Dengue battle -

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Dengue battle

Broadcast: 09/12/2010

Reporter: Peter McCutcheon

Australian scientists are using biological warfare to tackle dengue fever.

Transcript

KERRY O'BRIEN, PRESENTER: Researchers in Queensland are preparing for a biological assault on
Dengue Fever. In the New Year they'll be releasing mosquitoes deliberately infected with a bacteria
that stops Dengue spreading. It's the first part of an international program in part financed by
the Bill and Melinda Gates Foundation based on the work of Australian scientist Professor Scott
O'Neill. If successful, the biological control could significantly reduce the risk of a
life-threatening disease that affects tens of millions of people around the world. From North
Queensland, Peter McCutcheon reports.

PETER MCCUTCHEON, REPORTER: The backyards of two small North Queensland communities are being
meticulously prodded and scrubbed. It's the lead-up to an extraordinary attempt to rein in one of
the world's most widespread and debilitating diseases, Dengue Fever.

SCOTT RITCHIE, MEDICAL ENTOMOLOGIST, JCU: This is a game-changer. It's not gonna eliminate the risk
of Dengue, but reduce it would reduce it and we probably wouldn't be looking at thousand cases of
runaway Dengue epidemics or causing millions and millions of dollars to control.

PETER MCCUTCHEON: This clean-up is preparing for the release of mosquitoes deliberately infected
with a bacterium that stop Dengue from spreading.

SCOTT O'NEILL, BIOLOGIST, UQ: I don't want to over-promise the technology. But certainly if it's
successful in our best case scenario, it could have the potential to have a major impact on Dengue
globally.

PETER MCCUTCHEON: Dengue Fever is a potentially fatal virus that affects more than 50 million
people a year. It's usually transmitted through a single species of mosquito, aedes aegypti, that
only lives in urban environments. Thousands of North Queenslanders have been infected with Dengue
over the past decade, with three reported deaths.

SCOTT RITCHIE: The amount of Dengue coming into Australia's gettin' worse every year and the
outbreaks overseas appear to be getting worse.

PETER MCCUTCHEON: The plan to eliminate Dengue had its origins in research carried out by Professor
Scott O'Neill a quarter of a century ago. He was fascinated by a relatively obscure bacterium known
as wolbachia.

SCOTT O'NEILL: Wolbachia's a very interesting bacterium. It lives just within insects and it lives
within the cells of insects.

PETER MCCUTCHEON: This area of research may have well been a dead end, but through persistence and
a bit of luck, Professor O'Neill discovered a strain of wolbachia that reduced the life span of the
aedes aegypti mosquito. And then more recently, he made a second fortuitous discovery. This
bacteria strain also stopped Dengue from being transmitted altogether.

SCOTT O'NEILL: We're not over the finish line by any means at the moment and we wake up every
morning wondering whether to know whether this is the day that it all comes crashing down. But so
far, so good. We've had a great run of luck.

PETER MCCUTCHEON: Three months ago Professor O'Neill's team was given permission to put the theory
into practise with the release of wolbachia-infected mosquitoes in the small, geographically
isolated communities of Yorkeys and Gordonvale on the north and south fringes of Cairns. Gordon
Vale has a chequered history of biological controls, being one of the release points for the
infamous cane toad in the 1930s. But unlike the cane toad, the wolbachia bacterium has been
subjected to rigorous scientific scrutiny.

PAUL DE BARRO, ECOLOGIST, CSIRO: It's a bacteria that infects invertebrates, not vertebrates. So,
humans, livestock, dogs, cats, never been found.

PETER MCCUTCHEON: CSIRO ecologist Dr Paul De Barro was part of the team that assessed the risk of
the wolbachia trial. He concluded the main potential problem was that authorities could abandon
other Dengue control measures.

PAUL DE BARRO: The main risk is that it is so successful that investment in maintaining our
capacity to respond to other mosquito issues, other disease issues related to mosquitoes is run
down. It's not a silver bullet. It is part of an integrated management program.

PETER MCCUTCHEON: The wolbachia-infected mosquitoes being reared at James Cook University in Cairns
will be released early in the new year as part of a trial funded by the Australian and Queensland
governments as well as the Bill and Melinda Gates Foundation.

So this is what you'll be taking into the field?

SCOTT RITCHIE: This is it, Peter. There's about 40 mosquitoes in here, a mixture of male and female
aedes aegypti, infected with wolbachia and about every fourth house will open this up and let 'em
go.

PETER MCCUTCHEON: Dr Scott Richie headed Queensland Health's Dengue response team and has now been
seconded to the wolbachia trial.

SCOTT RITCHIE: These mosquitoes should go out and mate with the wild mosquitoes and by the end of
the wet season all the aedes aegypti mosquitoes should be infected with a bacteria. That's the game
plan.

PETER MCCUTCHEON: But before the release of the infected mosquitoes, researchers are asking
residents to co-operate with a program to suppress existing wild populations of the aedes aegypti.

BRIAN MONTGOMERY, MEDICAL ENTOMOLIGST: What we want to do I guess is give every chance of success
that these wolbachia mosquitoes will basically dominate the local mosquitoes, and also what we want
to do is make sure that people don't have a misconception that there are more mosquitoes than
normal.

PETER MCCUTCHEON: Gordonvale resident Frank Steene is happy to help.

FRANK STEENE, GORDONVALE RESIDENT: I was very apprehensive originally. I thought, you know, what
happens if these things happen in life. But we must remember that the wolbachia is in other insects
in the area and they've done a lot of research into this sort of thing.

PETER MCCUTCHEON: So you feel quite relaxed about it?

FRANK STEENE: I am now. I'm very relaxed.

PETER MCCUTCHEON: From the laboratory to the field, this ground-breaking research is in effect
immunising mosquitoes against the Dengue virus, and with trials later planned for Vietnam and
Thailand, it could have a global impact.

When you began looking at what is a relatively obscure bacteria 20, 25 years ago, did you ever
think it would lead to this?

SCOTT O'NEILL: No, I didn't. You know, I've always wanted to do scientific work that might have the
potential to be applied and have some impact, and so we've always been pushing in that direction,
but it's an unusual situation for a scientist to spend most of their time working in a laboratory -
to take an idea from the laboratory out into the field where hopefully it might have some impact.
So, we're really excited about it.

KERRY O'BRIEN: Peter McCutcheon with that report.