Genetically Modified Mosquitoes Could Combat Malaria, Scientists Say

Genetically modified mosquitoes could be used to combat malaria, scientists say.

ByMARIA CHENG<br>AP Medical Writer
January 08, 2009, 1:13 AM

June 19, 2008&#151; -- LONDON (AP) - In a cramped, humid laboratory in London,mosquitoes swarming in stacked, net-covered cages are beingscrutinized for keys to controlling malaria.

Scientists have genetically modified hundreds of them, hoping tostop them from spreading the killer disease.

Faced with a losing battle against malaria, scientists areincreasingly exploring new avenues that might have seemedfar-fetched just a few years ago.

"We don't have things we can rely on," said Andrea Crisanti,the malaria expert in charge of genetically modifying mosquitoes atLondon's Imperial College. "It's time to try something else."

Malaria kills nearly three million people worldwide every year,mostly in sub-Saharan Africa. Millions of bed nets have been handedout, and villages across the continent have been doused withinsecticide. But those measures haven't put a significant dent inmalaria cases.

After a string of failed initiatives, the United Nationsrecently announced a campaign to provide bed nets to anyone whoneeds them by 2010.

Some scientists think creating mutant mosquitoes resistant tothe disease might work better.

"We still have a malaria burden that is increasing," said YeyaToure, a tropical disease expert at the World Health Organization.

"Under such circumstances, we have to investigate whethergenetically modified mosquitoes could make a difference," saidToure, who is not involved in the Imperial College research.

The Bill & Melinda Gates Foundation has found the work sopromising it has invested nearly $38 million into geneticstrategies to stop mosquitoes from transmitting diseases likemalaria and dengue fever.

"This is one of those high-tech, high risk innovations thatwould fundamentally change the struggle between humans andmosquitoes," said Dr. Regina Rabinovich, director of infectiousdiseases development at the Gates Foundation.

Mosquitoes bred to be immune to malaria could break thedisease's transmission cycle. "That is the nirvana of malariacontrol," said Rabinovich. "It would potentially transform whatthe field looks like."

In 2005, Crisanti proved it was possible to create a geneticallymodified mosquito by inserting a gene that glowed fluorescent greenin males.

Among other possibilities, he and his team are now planning tocreate sterile male mosquitoes to mate with wild female mosquitoes,thus stunting population growth. They are also trying to engineer amalaria-resistant mosquito.

Last year, American researchers created mosquitoes resistant toa type of malaria that infects mice. Others are altering the DNA ofthe mosquitoes that spread dengue.

But not everyone thinks these super mosquitoes are such a goodidea. Some scientists think there are too many genetic puzzles tobe solved for modified mosquitoes to work.

The malaria-causing parasite, which mosquitoes then transmit tohumans, is simply too good at evading anything scientists mightdevise to protect the mosquito, argued to Jo Lines, a malariaexpert at London's School of Hygiene and Tropical Medicine.

"It's a series of arms races that the parasite has consistentlywon," Lines said. Whenever mosquitoes have developed genesresistant to the malaria-causing parasite, the parasite has alwaysfound a way around it, Lines said.

Quantity might also be a problem. "You are going to need toproduce billions of these mosquitoes if this is ever going towork," Lines said.

Some environmentalists worried that genetically modifiedmosquitoes might wreak havoc in the ecosystem.

"Can't we just give mosquito nets to people instead of lookingat these really complex technological fixes that mess with the verydelicate balance of nature and evolutionary history?" askedGillian Madill, a genetic technologies campaigner at Friends of theEarth in Washington.

Rabinovich said rigorous testing would be done before releasingany genetically modified mosquitoes into the wild.

"It's not nice to fool with Mother Nature," she said. "But ifyou can come up with another way of tackling (malaria), this is notsomething that one walks away from without fully evaluating it."

Over the next year, Crisanti hopes to finalize plans for a testrelease of genetically modified mosquitoes in southern Italy.There, millions of the insects will be set loose in large cages todetermine things like how they might interact with wild mosquitoesand how many would be needed to knock out malaria.

Crisanti acknowledged there might be unintended consequences ofreleasing genetically modified mosquitoes into the wild, althoughhe could not predict what they might be.

The scientist said it was a risk worth taking.

"I think there is a moral good to doing it," he said. "If wedo this right, the mosquitoes will get rid of malaria for us."

(Copyright 2008 by The Associated Press. All Rights Reserved.)

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