<i>Plasmodium</i>-associated changes in human odor attract mosquitoes.

Abstract

Malaria parasites (<i>Plasmodium</i>) can change the attractiveness of their vertebrate hosts to <i>Anopheles</i> vectors, leading to a greater number of vector-host contacts and increased transmission. Indeed, naturally <i>Plasmodium</i>-infected children have been shown to attract more mosquitoes than parasite-free children. Here, we demonstrate <i>Plasmodium</i>-induced increases in the attractiveness of skin odor in Kenyan children and reveal quantitative differences in the production of specific odor components in infected vs. parasite-free individuals. We found the aldehydes heptanal, octanal, and nonanal to be produced in greater amounts by infected individuals and detected by mosquito antennae. In behavioral experiments, we demonstrated that these, and other, <i>Plasmodium</i>-induced aldehydes enhanced the attractiveness of a synthetic odor blend mimicking "healthy" human odor. Heptanal alone increased the attractiveness of "parasite-free" natural human odor. Should the increased production of these aldehydes by <i>Plasmodium</i>-infected humans lead to increased mosquito biting in a natural setting, this would likely affect the transmission of malaria.