Malaria is one of the
world's deadliest diseases, infecting millions annually. More than a million
children die each year from the disease, which is spread by mosquitoes. But
mosquitoes are starting to become resistant to the insecticides used to control
them. Now researchers have found some genes in mosquitoes that allow them to
survive the chemicals.
Hilary Ranson from the Liverpool School of Tropical Medicine says one of the
most effective weapons against the spread of malaria has been the use of
bednets. But bednets need to be soaked several times a year in an insecticide,
most commonly a pyrethroid type insecticide.
These insecticides have been very successful for malaria control, but in recent
years we are seeing a growing trend of increasing resistance to this insecticide
class, and this is really worrying because we don't have many other
alternatives
Ranson says there are some areas in Africa where more and more malaria-carrying
mosquitoes are becoming resistant to the pyrethroid insecticides.
So she and an international team looked for what made some mosquitoes more
resistant.
We identified two enzymes that are found at much higher levels in the resistant
insects that we were studying than in the general susceptible population. And
we were able to show that these enzymes are able to break down the
insecticide... and so the resistant mosquitoes break down insecticide very
rapidly and so the insecticide is the longer toxic and no longer has the
desired effect of killing a mosquito.
Ranson and her team were also able to determine which genes in the mosquitoes
create these enzymes. She says this is important information.
Now we can think about modifying that insecticide so that it's still toxic even
to resistant insects. And the way we would do that is just to change the
property of the insecticide so that as well as killing the insect it also stops
the action of these enzymes and so it makes it last longer even in resistant
insects. And so, it effectively restores the efficacy the insecticides.
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Translated by: Buasawan Simmala
