Resistance is useless

Resistance is useless
Apr 8th 2009
From The Economist print edition


Evolutionary theory may help to fight a fatal disease



LIKE many other activities, global health has fashions. For the past couple of decades AIDS has captured both the imagination and the research dollars. Recently, though, the focus has shifted towards malaria, which kills a million people a year, most of them children, and debilitates hundreds of millions more. Insecticide-impregnated bednets designed to stop people being bitten by infected mosquitoes are being scattered throughout Africa. New drugs based on a Chinese herb called Artemisia have been introduced. And researchers are vying(competindo) with one another to be the first to devise(inventar,mostrar) an effective vaccine. But the traditional first line of attack on malaria, killing the mosquitoes themselves, has yet to have a serious makeover.
One reason is that time and again chemical insecticides have produced the same dreary pattern. They prove wonderfully effective at first, only to dwindle into uselessness. This is because evolution quickly throws up(apresenta) resistant strains. Indeed, spraying campaigns, which generally aim to kill mosquitoes before they can breed(cruzar), might have been devised as textbook examples of how to provoke an evolutionary response. With their competitors all dead, the progeny(crias,descendentes) of a mosquito carrying a mutation that can neutralise the insecticide in question have the world to themselves.
The upshot(=upcome=resultado) is that discovering a way to retain the anti-malarial benefits of insecticides without provoking an evolutionary response would be a significant breakthrough(inovação). And that is what Andrew Read of Pennsylvania State University and his colleagues think they have done. They have rethought the logic of insecticides, putting evolutionary theory at the centre, instead of a simple desire to destroy the enemy. The result is a modest proposal to deal with the problem of resistance.