Infection with the Zika or dengue viruses alters the skin’s microbiome, increasing the production of compounds that attract mosquitos. However, treatment with a common acne medication may negate this effect.

Researchers are looking into ways to reduce the spread of mosquito-borne diseases like Zika and dengue fever.
Researchers are looking into ways to reduce the spread of mosquito-borne diseases like Zika and dengue fever.

Humans and mice infected with Zika or dengue viruses secrete a chemical that makes them more appealing to mosquitos, increasing their chances of being bitten again and spreading these viruses. Researchers were able to reduce the appealing scent with a common acne medication after identifying the chemical attractant.

Dengue fever infects approximately 400 million people worldwide each year and kills approximately 40,000 people. The Zika virus infects hundreds of people each year, and infection during pregnancy can cause serious health problems in newborns. Mosquitoes transmit the viruses through their saliva when they feed on the blood of a host.

Gong Cheng of Tsinghua University in China and his colleagues were aware that mosquito-borne pathogens such as malaria can alter our scent to make us more appealing, prompting them to wonder if Zika and dengue could do the same.

In their experiment, the researchers gave mosquitos the option of eating an uninfected mouse or a mouse infected with the dengue or Zika viruses. They discovered that infected mice attracted roughly twice as many mosquitos as uninfected mice.

The researchers also examined molecular compounds found on the skin of infected and uninfected mice and humans, identifying several that were most prevalent in Zika and dengue-positive hosts.

The smelly compounds were then wiped onto the backs of mice and human hands to see which scents were most appealing to mosquitoes. Acetophenone, which was abundant in both humans and mice infected with either virus, had the most enticing odor.

Mosquitoes rely heavily on scent to find a meal, picking up on subtle chemical signals that humans cannot, according to James Logan of the London School of Hygiene & Tropical Medicine, who was not involved in the study. He observes that humans are covered in a complex mixture of over two dozen smells, many of which make us more or less appealing to hungry insects.

There have previously been indications that diseases such as malaria and covid-19 can affect a host’s microbiome, causing the bacteria that live in and on the skin to produce varying amounts of specific compounds. While the researchers were not surprised to discover that this was also true for Zika and dengue, they were pleased to identify a single mosquito-enticing molecule, says Cheng.

Acetophenone, which can also be found in some fruits and cheeses, is routinely produced by bacteria in human and mouse skin but is usually suppressed by the skin’s natural antimicrobial peptides. Infected hosts appear to produce fewer peptides. The virus can spread more easily to new hosts by transforming the infected mouse or person into a more appealing meal.

After identifying the compound, the researchers wanted to see if they could stop it from being produced. Using previous research as a guide, they decided to give the mice isotretinoin, a common acne medication known to increase the production of antimicrobial peptides. When they exposed the drug-treated mice to mosquitoes, the insects no longer preferred the infected individuals.

The researchers intend to investigate the skin odors of people infected with Zika and dengue viruses next. They believe that the isotretinoin treatment will deter mosquitos from feeding on humans.

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