The hosts’ scent attracts mosquitoes that cause dengue and Zika viruses.

Mosquitoes are one of the most dangerous carriers or vectors of disease in the world. In fact, with more than 750,000 deaths occur annually, mosquitoes, with no competitors that closely follow them, are the deadliest animals in the world. Among the diseases transmitted by these bloodsuckers are such well-known ones as malaria, Nile virus, yellow fever or Japanese encephalitis.

But also dengue or Zika, and it is in relation to these last two diseases that a group of scientists led by Peking University made a very relevant discovery. The results of their study are published this week in the journal cell entitled Volatile substances from the skin microbiota of hosts infected with flavivirus increase the attractiveness of mosquitoes.which states that These two viruses change the scent of their hosts to attract mosquitoes. and make your own survival easier.

Viruses that mosquitoes use

He dengue It is a disease transmitted by mosquitoes in tropical regions of the world and sometimes in some subtropical regions. Symptoms include fever, rash and pain, but can sometimes worsen and cause severe bleeding and even death. In fact, according to the US National Institute of Allergy and Infectious Diseases, there are more than 50 million cases of dengue worldwide, of which about 20,000 are fatal, most of them in children.

He Zika is another viral disease transmitted by mosquitoes of the same family as dengue fever: mosquitoes of the genus Aedes. Although Zika rarely causes serious illness in adults, a recent outbreak in South America has caused serious birth defects in the fetuses of infected pregnant women.

Types of mosquitoes Aedes aegypti And Aedes albopictus They are respectively carriers of the Zika virus and dengue fever.

These viruses, both included in the so-called flavivirus, survival and reproduction depend on both the hosts they infect and the vectors through which they spread, in this case mosquitoes. If any of these are missing, that is, if all the potential hosts disappear or all the mosquitoes die, the virus will disappear along with them.

For example, during the yellow fever outbreak in Philadelphia in 1793, the onset of autumn frost killed off local mosquitoes and the outbreak ended. In tropical climates, on the other hand, the lack of frost means there are always mosquitoes, so for the virus to spread it only takes one biting an infected host animal. But it doesn’t stop there, because a team led by Tsinghua University researcher Gong Cheng and the paper’s lead author has just discovered that The Zika and dengue viruses appear to have developed a sneaky way to improve their chances of spreading and surviving.as we already said, by changing the smell of the skin of your guests.

Zika and dengue: the war being waged on your skin

Researchers suspected that dengue fever and the Zika virus might somehow manipulate their hosts to attract mosquitoes. Thus, it is a proven fact that Both malaria and general inflammation can change a person’s odor.

Therefore, they believed that dengue and Zika virus infections may exhibit the same mechanism.

To confirm their hypothesis, the first thing the scientists focused on was testing whether mosquitoes showed a preference for mice infected with these diseases. In fact, when given a choice between healthy mice and dengue-infected mice, the mosquitoes were more attracted to the dengue-infected mice.

Why do some types of mosquitoes love us so much?

They then analyzed the odor molecules in the skin of infected and healthy mice and thus identified several that were more common in the latter and tested them individually. So they applied them to both mice and the hands of healthy human volunteers and found that a specific molecule, acetophenone was particularly attractive to mosquitoes. On the other hand, tests done on people with dengue showed the same thing: greater production of acetophenone made them more attractive to mosquitoes.

Acetophenone is produced by certain bacilli-type bacteria that grow on the skin of humans and mice. Normally, the skin produces an antimicrobial peptide that controls the bacilli population. But it turns out that when mice become infected with dengue and Zika, they don’t produce as much of the antimicrobial peptide and the bacillus grows faster. “This is how the virus can manipulate the skin microbiome of its hosts to attract more mosquitoes and spread faster!” explains Penghua Wang, an immunologist at UConn Health and another co-author of the study. The findings may explain how mosquito viruses manage to survive for so long.

However, the researchers also began looking for a way to mitigate this effect, so they gave mice with dengue a vitamin A derivative called isotretinoin,

and is known to increase skin antimicrobial peptide production. Thus, mice treated with isotretinoin secreted less acetophenone, making them less attractive to mosquitoes and potentially reducing the risk of the virus infecting other potential hosts.

The team explains that the next step will be to analyze more people with dengue fever and the Zika virus to see if this connection between skin odor and the microbiome occurs in the same way in the real world, that is, outside of controlled conditions. and test whether isotretinoin reduces acetophenone production in both humans and diseased mice. We may be taking the first steps in finding the formula for a new generation of mosquito repellents, and with it the possibility of saving hundreds of thousands of lives every year.