Mosquitoes sniff out hosts infected with certain viruses, researchers find

Infections by the viruses that cause #Zika and #Dengue fever alter how their hosts smell, making them more likely to be bitten by #mosquitoes.

The study also identified a potential way to block the scent, using the #acne medication, isotretinoin which is also known as #Accutane.

The smell is linked to high levels of #acetophenone Smell can be a powerful motivator. The fragrance of freshly baked cookies may compel a person to come to the kitchen, while a musky perfume might entice a date. In the mosquito universe, an irresistible scent is one produced by two dangerous viruses after hijacking a human body, a new study found. The viruses that cause Zika and dengue fever alter how their hosts smell, making them more likely to be bitten by mosquitoes, according to researchers. The discovery was announced Wednesday in the journal Cell and is the result of experiments on both mice and people. The scientists also identified a potential way to block this scent and stop the spread of the disease, using a medication already known to people struggling with acne, isotretinoin, also known by the trade name Accutane. “In some countries, these mosquito-transmitted diseases are very prominent,” said co-author Penghua Wang, an assistant professor at UConn Health, the University of Connecticut’s school of medicine and medical center. “In the long run, if this medication really works, then people may have a way to prevent or at least reduce this burden.” The smell is linked to high levels of a compound called acetophenone, described by the study authors as a “potent attractant” for mosquitoes. It’s made by a bacteria that grows on skin, but normally skin secretes a protein that restrains it. However, this study suggests Zika and dengue suppress the production of this critical protein, allowing the bacteria to grow faster and for more acetophenone to emerge. This results in a scent that attracts mosquitoes and propels the cycle of infection forward. While people in tropical and subtropical areas — where these viruses thrive and are a leading public health concern — are likely to get bit by mosquitoes generally, this scent increases the odds that mosquitoes are biting infected individuals. Vectors like mosquitoes help viruses survive. When an infected mosquito bites a healthy person, it can transmit a virus. An infected person, meanwhile, can spread the virus to a healthy mosquito. Newly infected mosquitoes can go on to do more damage. Researchers previously discovered that malaria can alter the smell of its host, which in turn attracts mosquitoes. This suggested to the new study authors that it was worth investigating whether the same was true for Zika and dengue. Dengue is a viral infection caused by four closely related viruses. These viruses spread through the bites of two types of mosquitoes. While half of the world’s population is at risk of developing dengue, over 80% of cases are generally mild and asymptomatic, according to the World Health Organization. However, it can be more severe. While scientists report dengue cases may be undercounted because of Covid-19, on average it’s known to cause around 20,000 deaths each year. Zika belongs to the same family of viruses as dengue and is transmitted by the same kinds of mosquitoes. Most people with a Zika infection do not develop symptoms, and those who do experience ailments like fever, conjunctivitis and neurological complications. A Zika virus infection during pregnancy can also result in a birth defect called microcephaly. There is no specific vaccine or medicine for Zika virus. The dengue vaccine is only recommended for children between the ages of 9 and 16 who have already been infected — the aim is to prevent severe dengue in the future.

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