By Christopher Intagliata
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The dengue virus depends on mosquitoes to get around. But the virus may have evolved a way to speed its spread—by manipulating the behavior of its mosquito hosts. It makes them more bloodthirsty, and quicker to find a blood meal, than their uninfected counterparts. So says a study in the journal Public Library of Science Pathogens. [Shuzhen Sim, Jose L. Ramirez and George Dimopoulos, "Dengue Virus Infection of the Aedes aegypti Salivary Gland and Chemosensory Apparatus Induces Genes that Modulate Infection and Blood-Feeding Behavior"]
Researchers compared which genes were active in the salivary glands of infected and uninfected mosquitoes. And they found that dengue infection flipped the switch on 147 genes. As expected, some of those were immune genes—a common response to infection. But the virus also turned on genes involved in odor detection and blood-feeding. Which could make a mosquito better at sniffing out hosts, and quicker to plunge its proboscis into the skin for a snack.
Previous studies have shown malaria parasites can change a mosquito's behavior too, by making it more likely to feed on multiple victims—thus infecting more people.
And the researchers say we humans may also do the bidding of these pathogens. When infected we sweat—and the odor attracts other mosquitoes that feed on us and pick up hitchhiking pathogens for their next ride.