In the world of mosquitoes, scent is everything. It guides them to their next meal and, unfortunately, helps them spread some of the world’s deadliest diseases. A recent study published in Cell reveals that viruses like Zika and dengue don’t just infect their hosts—they also manipulate them, altering their scent to make them more attractive to mosquitoes. This discovery sheds new light on how these diseases spread and offers potential strategies for controlling them.
The virus-mosquito connection: A smell that sells
The study, led by researchers from the University of Connecticut’s UConn Health, found that Zika and dengue viruses increase the production of a skin compound called acetophenone, a powerful attractant for mosquitoes. Normally, human skin produces a protein that controls the bacteria responsible for producing acetophenone. However, these viruses interfere with this process, reducing the production of the protective protein and allowing bacteria to thrive. The result is a potent scent that makes infected individuals more appealing to mosquitoes, driving the cycle of infection. “Mosquitoes rely heavily on their sense of smell to find hosts,” explains Penghua Wang, assistant professor at UConn Health and co-author of the study. “By altering the way their hosts smell, these viruses increase the chances that mosquitoes will bite them, picking up the virus and spreading it to others.”
Unveiling the Evidence: Mice and Human Experiments
To explore this phenomenon, the researchers conducted a series of experiments on both mice and humans. They infected mice with Zika and dengue and observed mosquito behavior. In these experiments, they placed healthy and infected mice in interconnected cages with mosquitoes. The results were striking: about 70% of the mosquitoes were drawn to the infected mice, preferring their scent over that of healthy mice. The researchers didn’t stop there. They also tested the effect on humans by collecting odors from dengue patients and healthy volunteers. In a somewhat unconventional experiment, they attached filter papers with these scents to volunteers' hands and exposed them to mosquitoes.
The outcome was clear, the mosquitoes overwhelmingly chose the hands carrying the scent of dengue patients over the others. “We’ve known that mosquitoes are drawn to certain scents, but this is the first time we’ve seen how a virus can manipulate its host’s smell to attract mosquitoes,” says Wang. “This discovery helps explain how diseases like Zika and dengue continue to spread so effectively.”
A new hope: Could acne medication help?
In an intriguing twist, the researchers found a potential way to disrupt this scent manipulation. They treated infected mice with isotretinoin, a medication commonly used to treat acne, which is known to alter skin bacteria. This treatment reduced the levels of acetophenone produced by the bacteria on the mice’s skin, making them less attractive to mosquitoes. “Isotretinoin changed the bacterial composition on the mice’s skin, which in turn lowered the amount of acetophenone and reduced mosquito attraction,” explains Wang. “This suggests that similar treatments could potentially be used to protect humans from mosquito bites during infection.”
The road ahead: Expanding research and future implications
While the findings are promising, the study’s scope was limited, especially regarding human subjects. The research team is now planning larger studies, including trials in Malaysia, to determine if these findings hold true in a broader population. They hope to confirm whether isotretinoin or similar treatments could be a practical way to reduce mosquito bites in people infected with Zika or dengue. But the implications of this research don’t stop there. The study opens up new possibilities for controlling mosquito-borne diseases.
Scientists are exploring innovative approaches, including using genetic engineering tools like CRISPR to disrupt mosquitoes' sense of smell or alter their reproductive patterns. For instance, by silencing the olfactory neurons that detect human scents, researchers could potentially make mosquitoes less interested in biting humans, thereby reducing the spread of these deadly viruses. “This research gives us a deeper understanding of the relationship between viruses, mosquitoes, and their hosts,” says Wang. “If we can leverage this knowledge, we could develop new strategies to control the spread of diseases like Zika and dengue, which continue to pose a significant threat in many parts of the world.”
The bigger picture: combating mosquito-borne diseases
Mosquito-borne diseases remain a global health challenge, with Zika and dengue affecting millions of people every year, particularly in tropical and subtropical regions. Dengue alone infects hundreds of millions annually, with severe cases leading to tens of thousands of deaths. Zika, while often asymptomatic, can cause serious birth defects like microcephaly when contracted during pregnancy. Currently, there are no specific treatments or vaccines widely available for these viruses, making prevention critical. The discovery that these viruses can manipulate their host’s scent to attract mosquitoes underscores the complexity of controlling their spread. It also highlights the need for innovative approaches that go beyond traditional methods like insecticides and bed nets.
As scientists continue to unravel the mysteries of how viruses and mosquitoes interact, studies like this offer hope for new, more effective ways to protect vulnerable populations from these devastating diseases.