Viruses change human body odor to attract mosquitoes, a study has found.
Mosquitoes are one of the deadliest animals to humans. Malaria, yellow fever, dengue fever, Zika, and chikungunya fever are mosquito-borne diseases. This causes more than 1 million deaths annually.
Mosquitoes recognize humans as potential hosts by sensing a person’s body temperature, smell, and carbon dioxide emitted through respiration.
Recent studies have shown that dengue and Zika viruses can alter a person’s body odor, making them more attractive to mosquitoes.
A team of researchers from the Department of Immunology at the University of Connecticut in the United States placed mice infected with dengue virus or Zika virus, uninfected mice, and mosquitoes in glass chambers connected to each other.
Then, the airflow was controlled so that the smell of mice was directed to the mosquitoes through the connecting passages. As a result, more mosquitoes flocked to the glass room with the infected mice than the glass room with the uninfected mice.
The research team measured the mice’s carbon dioxide emissions and body temperature to determine where the cause was. And it was confirmed that these two conditions were not factors attracting mosquitoes.
The research team believes that mosquitoes may have been attracted to the smell of mice, and installed a filter to block odor transmission. Then, the number of mosquitoes flying to the infected and uninfected mice was similar.
The team also worked to identify which odor was the cause. The reaction of mosquitoes was examined by isolating 20 gaseous compounds from the odor exhaled by mice.
There were three major compounds that mosquitoes react to, and the most crucial compound was ‘acetophenone’.
The researchers interpreted that dengue and Zika viruses appear to cause more acetophenone to be released from the host’s body. This is because attracting mosquitoes can spread the virus to more hosts.
So how does a virus get its host to produce acetophenone? There are bacteria on the skin that release acetophenone as a metabolic by-product, which may be related. When the team removed the bacteria from the skin of infected mice, the number of mosquitoes that flocked to it decreased.
Is there any way to get rid of the smell that attracts mosquitoes? When the research team fed the infected mice with vitamin A derivatives for several days, the secretion of ‘RELM-α’, a molecule that fights microorganisms, increased. This reduced the number of acetophenone-releasing bacteria, which in turn reduced the number of mosquitoes that flock to it.
The research team explained that follow-up studies are needed to determine whether the risk of mosquito-borne diseases can be reduced through diet, etc. given that there are many vitamin A deficient populations in developing countries where mosquito-borne diseases such as Southeast Asia and Africa are prevalent.
By Moon Se-young, staff reporter [email protected]
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