
A Harvard University–based team has identified a chemical compound that, when applied to insecticide-treated bed nets, blocks malaria parasite transmission in mosquitoes without contributing to insecticide resistance.
Yesterday in Nature the researchers said that once-declining malaria death rates have recently stalled, partly due to widespread resistance of Anopheles mosquitoes to the insecticides used in long-lasting insecticide-treated nets (LLINs).
"One way to mitigate insecticide resistance is to directly kill parasites during their mosquito-stage of development by incorporating antiparasitic compounds into LLINs," they wrote. "This strategy can prevent onward parasite transmission even when insecticides lose efficacy."
Mosquitoes essentially disinfected
The researchers screened 81 chemical compounds with activity against the mosquito stages of the Plasmodium falciparum parasite, which causes malaria. Compounds were added to a dimethyl sulfoxide (DMSO)–acetone solution and directly pipetted onto the dorsal thorax of female Anopheles gambiae mosquitoes before infection with P falciparum.
The solution helped disrupt mosquito cuticle and enhance compound membrane permeability. Mosquitoes were then given a P falciparum–containing blood meal 7 days before the scientists counted oocysts (infectious parasite structures) in the digestive tract.