Quantity might also be a problem. "You are going to need to produce billions of these mosquitoes if this is ever going to work," Lines said.
Some environmentalists worried that genetically modified mosquitoes might wreak havoc in the ecosystem.
"Can't we just give mosquito nets to people instead of looking at these really complex technological fixes that mess with the very delicate balance of nature and evolutionary history?" asked Gillian Madill, a genetic technologies campaigner at Friends of the Earth in Washington.
Rabinovich said rigorous testing would be done before releasing any genetically modified mosquitoes into the wild.
"It's not nice to fool with Mother Nature," she said. "But if you can come up with another way of tackling (malaria), this is not something that one walks away from without fully evaluating it."
Over the next year, Crisanti hopes to finalize plans for a test release of genetically modified mosquitoes in southern Italy. There, millions of the insects will be set loose in large cages to determine things like how they might interact with wild mosquitoes and how many would be needed to knock out malaria.
Crisanti acknowledged there might be unintended consequences of releasing genetically modified mosquitoes into the wild, although he 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 we do this right, the mosquitoes will get rid of malaria for us."
(Copyright 2008 by The Associated Press. All Rights Reserved.)