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Parasite may make malaria-infected mosquitoes love smelly humans

The parasite that infects a mosquito with malaria may be behind the bug's affinity for the human scent, a new study published in PLOS ONE on May 15 reveals.

Human skin lets out more than 350 different odor molecules, according to NPR. This includes a mushroom alcohol that gives our skin a moldy or meaty smell, and a compound also found in Chardonnay that gives us a buttery smell. The latter is also included in microwave popcorn to give it that butter scent.

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In 2010, 660,000 people worldwide died from malaria, which is transmitted via bites from mosquitoes, the World Health Organization stated. While it can be fatal, malaria is preventable and curable, according to the agency. Mosquitoes infected with the Plasmodium falciparum parasite have an increased rate of transmitting malaria. They consume larger, more frequent blood meals than those without the parasite.

For the new study, both Anopheles gambiae mosquitoes that were infected by the Plasmodium falciparum parasite and uninfected mosquitoes were exposed to human odors collected on nylon socks worn by one of the authors for 20 hours. Unworn socks were also thrown in the mix.

The infected mosquitoes landed on and bit the smelly nylon socks more times than the non-infected insects. The infected females seemed the most interested. Neither group was interested in the unworn socks.

It is already known that Anopheles gambiae mosquitoes have specific odor receptors that can detect some specific human smells. The scientists believe that the parasites make the mosquitoes want those certain scents more.

"We think it is giving them a heightened sense of smell. We are hypothesizing there is an alteration somewhere in their olfactory system that allows them to find us quicker," Dr. James Logan, senior lecturer in medical entomology at the London School of Hygiene and Tropical Medicine (LSHTM), told the BBC.

Researchers pointed out that the study could give us insight into how malaria is transmitted, because most studies are done on mosquitoes without the parasite. Now that we have knowledge of what attracts the infected, it can be used to develop products to help ward off the biting pests, they said.