2 Jan 2009, 1213 hrs IST, AFP


SYDNEY: Australian researchers funded by US billionaire Bill Gates on Friday claimed a breakthrough which could help in the fight against dengue
fever by stopping the often deadly disease in its tracks.

University of Queensland researchers said they have successfully infected the mosquito which spreads the tropical disease with a bacterium which halves its 30-day lifespan, thereby reducing its ability to transmit dengue to humans.

Scientists hope their work will help halt the spread of the painful and debilitating disease which affects up to 100 million people each year.

"The key is that really only very old mosquitoes are the only ones that are able to transmit the disease," said researcher Professor Scott O'Neill.

"What we've done is put this naturally occurring bacteria into the mosquitoes that actually halves their adult lifespan so they don't live long enough to be able to transmit the virus."

The research published Friday in the journal Science is the result of injecting 10,000 mosquito embryos with a bacterium that occurs naturally in fruit flies but has never been detected in dengue-carrying mosquitoes.

O'Neill said the test was designed to see whether the bacterium reduced the lifespan of the insects without killing them or preventing them from breeding and was able to be passed on to offspring.

He said while the laboratory tests, which involved researchers allowing the bacteria-infected mosquitoes to bite their arms because the species needs human blood to breed, had been successful, it would be several years before the technique would be tested in the wild.

"It's really a preventative strategy for preventing dengue fever outbreaks and what we've done is show that it's possible to be done in a laboratory," he said.

"The next stage is now to move it into a more realistic field setting."

There is no known cure or vaccine for dengue fever, which is transmitted by mosquitoes and kills more than 20,000 people each year. Also known as "breakbone fever," symptoms include high temperatures and muscle aches.

The Bill and Melinda Gates Foundation donated 10 million dollars to an international research team led by the University of Queensland into a means of defeating dengue fever in 2005.