Our understanding of how mosquitoes choose their prey is progressing step-by-step. Mosquitoes are considered the deadliest animal to humans, not just because of the curiosity this issue can generate or how annoying these animals are during the summer months. We already knew that smell was key, now we know that some viruses take advantage of this to look for new hosts.

Smell is the main prey detector.
Mosquitoes choose their prey based on a number of factors. Opinion between them, but above all the smell. Mosquitoes are sensitive to substances such as certain aldehydes, chemical compounds found on our skin from sweat. Bacteria living on our skin also play an important role in this equation and are responsible for having some of these chemicals on our skin.

What does the new study say?
A study appearing this week in the journal Cell signed by Chinese and American experts takes an important step forward in examining the role of mosquitoes in the spread of diseases such as Zika or dengue fever.

A similar study had already observed that malaria creates changes in the smell of malaria survivors, making them more attractive to mosquitoes. The new study found that the same thing happened with those infected with Zika and dengue viruses. The study was mainly conducted in mice, although some were completed with some stages being studied in humans as well.

First steps in mice.
To test the hypothesis that viruses make their hosts more attractive to mosquitoes through changes in their odor, the researchers first tested whether the insects could bite infected mice more than healthy mice. The result was positive.

They first denied that this was the cause of carbon dioxide emissions and differences in body temperature, and then they introduced an odor filter and confirmed that this was the deciding factor.

Chemical problem.
The researchers isolated 20 compounds “suspected” as attracting mosquitoes’ attention. Three of these compounds were able to replace the reaction of the mosquitoes’ sense organs (antennas). After applying these scents to mice and humans, they found what attracts mosquitoes: acetophenone.

One step further.
There is still one step left to understand how viruses attract mosquitoes and how this chemical compound forms in our skin. To know the role of bacteria in the presence of chemicals in our environment. Specifically, acetophenone is related to a type of bacillus (elongated shaped bacteria).

Such bacteria were more abundant in dengue and Zika-infected mice, leading the researchers to conclude that “viruses can alter the scent of their hosts by altering their skin’s microbiome.” Study authors in an article in The Conversation.

Ways to apply this knowledge.
Avoiding mosquito bites goes beyond the simple discomfort they cause, it can save lives. Therefore, it is very important to know more about how these animals orient themselves and how to prevent them from doing so. This last study has also addressed this last aspect.

They identified RELMα, a molecule with an important antimicrobial role in the skin. Production of this molecule, in turn, is linked to levels of vitamin A. Again in mice, the team confirmed a beneficial effect of administering a derivative of this vitamin to animals by increasing RELMa levels.

Mosquitoes wreak havoc, particularly in poor areas of the world, so the relationship between food shortages and infectious diseases has multiple dimensions. This work paves the way for improving the life expectancy of millions of people. We have the tools to mitigate these deficits, but new efforts will still be needed to put what the scientists are telling us into practice.

Image | Himas Rafeek