Do We Dare Breed A Skeeter?

Malaria experts are buzzing with the news that scientists have cracked the genetic codes of both the malaria parasite and the principal mosquito that carries it to humans. Malaria is one of the world's deadliest diseases striking some 500 million people a year and killing as many as 3 million of them. So the genetic secrets hidden in those codes could help drug companies design more effective treatments, better repellents and maybe even a vaccine. The information could also be used, some scientists suggest, to breed genetically modified mosquitoes that are resistant to the malaria parasite. Release these mutant bugs in the wild, the thinking goes, and they will occupy the same ecological niche as wild mosquitoes, competing for food and, with any luck, eventually displacing them.

Could it work? Perhaps, according to reports in the current issues of Science and Nature, but it wouldn't be easy scientifically or politically. Investigators at New York University have already located a malaria-resistance gene, but there's no guarantee that new bugs carrying it would have any evolutionary advantage over the old ones. Besides, parasite-host relationships are notoriously protean; as soon as resistance genes appear, the parasites develop counter-resistance. And there's always the possibility that the experiment could backfire, creating swarms of mutant mosquitoes that are even worse than the ones we have now.

For all these reasons, some argue, the $34 million used for sequencing the genomes, and the millions of dollars more it would cost to develop aresistant bug, might be better spent on sending the tools we already have pesticides, netting, malaria drugs into Africa and other parts of the malaria-plagued world where they are in desperately short supply.