Some viruses make people smell more enticing to mosquitos

Zika and dengue viruses cause death and suffering in tropical regions worldwide. They are part of the same infamous family as Yellow fever, Japanese encephalitis, and West Nile. Although the Zika virus rarely kills adults, a recent outbreak in South America caused multiple congenital disabilities, often cutting lives short. 

Dengue is a killer of both adults and children; every year, it kills roughly 20,000 people, primarily children. These viruses depend on mosquitoes to spread. In tropical areas where mosquitoes don’t die off annually, the diseases are unrelenting. 

In what seems like something out of an intriguing horror movie, a team of scientists led by UConn Health has discovered that dengue and zika viruses – like malaria – have adapted ways to increase their transmission rates. The viruses modify their hosts’ scent in a way that attracts more mosquitoes who feed on them and then carry the virus to non-infected individuals. 

A multinational group of scientists first saw that mosquitoes had a preference for mice who were infected with dengue. After analyzing the skin of the infected mice, they determined which molecules the mice’s skin had in common and applied these molecules to non-infected mice and humans. The experts found that the mosquitoes were attracted to acetophenone, a type of molecule secreted by a common bacteria called Bacillus. 

Bacillus is usually kept in check by an antimicrobial peptide. However infected humans and mice don’t produce as much of this peptide. Therefore, the bacteria multiply faster and more acetophenone is released. Mosquitos find the scent of acetophenone intoxicating.

Study co-author Penghua Wang explained: “The virus can manipulate the hosts’ skin microbiome to attract more mosquitoes to spread faster!”

However, hope is not lost. When the researchers gave dengue-infected mice isotretinoin, a vitamin A derivative, the mice’s skin began producing more antimicrobial peptides and gave off less acetophenone making them less attractive to mosquitoes. The experts hope that by starting a vitamin A regime, infected individuals could become less attractive to mosquitos, which will help slow the spread.  

Although the research is promising, human trials will need to be conducted. According to Wang, further investigation is needed to determine whether the connections the team discovered exist under real-world conditions and whether isotretinoin works to reduce acetophenone production in humans as it does with mice.

The study is published in the journal Cell.

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By Erin Moody , Earth.com Staff Writer