Mosquitoes Remade: Scientists Reinvent Agents of Illness to Become Allies in Fight against Disease

Article excerpt


It's a bit unnerving that Scott O'Neill bursts out laughing at the basic premise behind the story you are beginning to read.

He is dean of the science faculty at Monash University in Australia and lead scientist for research on developing bacteria-infected mosquitoes as a public health tool. The premise put forth was that scientists suddenly have made visible progress on a daydream that has been around for at least 50 years. Apparently, though, O'Neill thinks the "suddenly" is funny.

To the general insect-bitten public, a mosquito that fights disease instead of spreading it is the flying car of public health. Twentieth century science was supposed to create all kinds of marvels. But it's a new millennium, cars are still grounded and mosquitoes are still dangerous. They pass along maladies, including malaria, yellow fever and dengue, that together kill hundreds of thousands of people each year, and often stump vaccine makers and drug developers. Small, frail-bodied creatures, easily knocked out of the air with the slap of a rolled-up science magazine, rank among the deadliest animals on Earth.

But now, retrofitted Aedes aegypti mosquitoes that might interrupt disease transmission are flying around freely in a wave of real-life tests.

In 2010, the British company Oxitec announced results of the first known tests of free-flying transgenic mosquitoes, a milestone for both friends and foes of genetic engineering. The mosquitoes3 million of them--were engineered to start a population crash after infiltrating wild, potentially disease-spreading A. aegypti swarms in a village on the Caribbean island of Grand Cayman. And last year, O'Neill and his colleagues reported results of field trials using a completely different strategy. His team's mosquitoes, several hundred thousand of which were released into towns in Queensland, are not transgenic and are not intended to reduce the overall number of mosquitoes. Instead, regular mosquitoes infected with a bacterial disease that makes them far less likely to spread dengue were supposed to replace the usual swarms. Both research groups are continuing their tests this year, and both are discussing expansions (Vietnam for O'Neill's group and Key West, among other places, for Oxitec).

Yes, these are just tests. The basic strategies have their pluses and minuses. And who knows what chances the saboteur mosquitoes have for ultimate success in fighting disease. But the big news is that the insects are actually out of the lab. The last widely reported releases for mosquito control that made it this far ended in 1981. Public health at least has a flying tricycle, soaring in from out of the blue.

O'Neill doesn't see it that way. With a note of cheerful teasing, he says: "Well, I'd say you took your eyes off the ball."

From inside the mosquito effort, he wouldn't describe the outdoor tests as a pop-up surprise, but more as a matter of researchers continuing to attack the problems at hand. Presented with the same premise of sudden visible progress, Oxitec's chief scientific officer, Luke Alphey, merely says that progress toward a better mosquito "took longer than we expected."

Listening to their accounts of what happened behind the scenes, however, makes the progress sound more, rather than less, surprising. It's easy to understand why outsiders took their eyes off the ball. The effort stalled for years at a time, careened sideways and rolled backward as much as forward.

Death by mozzle

The perils of mosquitoes can set anyone dreaming. Female mosquitoes have evolved marvels of stealth hypodermics, drawing out blood in search of proper prenatal nutrition. So living amid the surreptitious blood-seeking moms is the disease-risk equivalent of sharing needles with anybody nearby who has some uncovered skin and a pulse.

These flying syringes spread quite a lot of unpleasantness: Beyond malaria, dengue and yellow fever, there's also West Nile virus; lymphatic filariasis, with its elephant-scale swellings; St. …