Mosquitoes spread the disease by acting as carriers of viruses and other pathogens, because a mosquito that bites a person infected with the virus can pick up the virus and pass it on to the next person it bites

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For immunologists and infectious disease researchers, a better understanding of virus-host interactions could provide new strategies for preventing and treating mosquito-borne diseases, Penghua Wang, an immunologist at the University of Connecticut, writes for The Conversation.

In a recently published study, Wang and his colleagues found that certain viruses can change a person's body odor to make it more attractive to mosquitoes, leading to more bites that allow the virus to spread.

Wang and his team investigated whether other mosquito-borne viruses, such as dengue and Zika, can also change a person's scent to make them more attractive to mosquitoes, and whether there is a way to prevent these changes.

"To investigate this, we placed mice infected with the dengue or Zika virus, uninfected mice and mosquitoes in one of three arms of a glass chamber.

"When we applied airflow through the mice's chambers to direct their odors toward the mosquitoes, we found that more mosquitoes chose to fly to the infected mice than to the uninfected mice," Wang said.

Wang and his team ruled out carbon dioxide as the reason mosquitoes were attracted to infected mice, because while Zika-infected mice emitted less carbon dioxide than uninfected mice, dengue-infected mice did not change their emission levels.

They also ruled out body temperature as a potential attraction factor, as mosquitoes did not discriminate between mice with elevated or normal body temperatures.

After that, they assessed the role of body odor in increasing the attraction of mosquitoes to infected mice.

"After placing filters in the glass chambers to prevent the mouse scent from reaching the mosquitoes, we found that the number of mosquitoes flying towards infected and uninfected mice was comparable.

This suggests that there was something in the odors of infected mice that attracted mosquitoes to them," Wang writes.

To identify the odor, they isolated 20 different gaseous chemical compounds from the odor emitted by infected mice.

Thus, they found that three gaseous chemical compounds stimulated a significant response in mosquito antennae.

"When we applied these three compounds to the skin of healthy mice and the hands of human volunteers, only one, acetophenone, attracted more mosquitoes compared to the control test.

We found that infected mice produced 10 times more acetophenone than uninfected mice,” explains Wang.

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Similarly, Wang and his team found that odors collected from the armpits of dengue patients contained more acetophenone than those of healthy people.

When we applied the odors of dengue patients to one hand of a volunteer and the odors of a healthy person to the other, mosquitoes were consistently attracted to the dengue-scented hands, Wang says.

These results suggest that dengue and Zika viruses are able to increase the amount of acetophenone produced, making them more attractive to mosquitoes.

Acetophenone, in addition to being a chemical commonly used as a flavoring in perfumes, is also a metabolic byproduct commonly produced by certain bacteria that live on the skin and guts of humans and mice.

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