Scientists have discovered that one of the most widely used insect repellants, DEET (N,N-deithyl-meta-touamide), fends off mosquitoes by blocking their ability to smell their human targets.
It is hoped the discovery will lead to safer and more effective insecticides. Although DEET has been used for 50 years in products such as Peaceful Sleep and Tabard, it is not suitable for babies and small children — who are particularly vulnerable to mosquito-borne diseases such as malaria and dengue fever. Products containing DEET also have the disadvantage that they have to be often and liberally reapplied.
Malaria infects between 350m and 500m people each year, killing about a million of them, mostly young children in sub- Saharan Africa. The disease costs developing countries an estimated $12bn in lost productivity.
Topical insecticides are an important part of malaria control but new-generation products are desperately needed, said Rocke feller University molecular neurobiologist Leslie Vosshal. She is co-author of a paper published today in the journal Science describing DEET's mechanism.
"The telephone and television have evolved since the 1950s but insecticides haven't," she said.
"The only way we can improve on existing technology is to understand how it works. Everyone knows DEET is useful, but until now there has never been a satisfactory explanation of how it works," she said.
It turns out that DEET "jams up the works" of the mechanism by which insects smell, by blocking key odour receptors that rely on a protein called OR83b. DEET masks human odours that would ordinarily tell a passing mosquito that there is food at the ready.
"Now we can apply similar tricks the pharmaceutical industry uses to screen millions and millions of molecules to find ones that block OR83b better than DEET," she said.
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