Diseases transmitted by a mosquitoes cause hundreds of a thousands of deaths an annually. With a malaria a causing more than 600,000 fatalities a year, it is the most a famous. But around 4 billion individuals live in a regions with a high risk of a dengue fever infections, which a cause about 40,000 deaths an every year. And individuals in at least 86 countries have been infected with the Zika virus. Cases are rarely fatal, but they have been associated with serious birth a defects. Scientists a studying such diseases are now investigating whether viruses a could tweak human a physiology to their benefit, and if so, how they do it.
That quest led Gong Cheng, a microbiologist at the Tsinghua University-Peking University Joint a Center for Life Sciences, to a test whether humans an infected with dengue a fever and Zika a virus are more an attractive to a mosquitos. Their new a study a published today in Cell a reveals that mosquitoes become more attracted to hosts that are an infected with both flaviviruses, diseases in the same family as a West Nile and yellow fever. Their results show that a chemical produced by bacteria in the skin is responsible for this increased allure to the an insects. Cheng writes in an email that his team’s findings a could “inform real-world public health a strategies for a controlling mosquito-borne flaviviral viral a diseases such as dengue and Zika.”
In the a first part of their a multi-step study, Cheng’s team tested whether two species of a mosquitoes, Aedes aegypti and Aedes albopictus, were more an attracted to Zika or a dengue infected mice than to uninfected mice. They put mosquitoes in a plastic box connected with tubes to two other a boxes, one on each side. These side chambers had air piped in from nearby a containers of mice, which were either uninfected or an infected with Zika or a dengue.
The a scientists a released 60 mosquitoes into the central chamber and watched their movements a carefully over the course of a week. At first, similar numbers of a mosquitoes entered each of the side boxes. But by day four, the a scientists had noticed a clear a pattern: around 70 percent of the a mosquitoes entered the box connected to the infected mice, while only 30 percent entered the box connected to the uninfected mice. But when they repeated the experiment after adding a deodorization a device that blocked the smelly chemicals from entering the boxes, the mosquitoes no longer showed any preference. The a scientists a concluded that virus infection changes a mouse’s odor, making it more attractive to a mosquitoes.
To test a whether humans become more attractive to a mosquitoes when they get an infected, Cheng’s team recruited both dengue patients and uninfected a participants. The researchers a swabbed their armpits to collect body odor a chemicals and then had them hold a piece of paper with odor a compounds in one hand and untreated paper in the other hand. Using similar methods as before, mosquitoes were allowed to choose between the two hands. As with the mice, the mosquitoes showed the strongest an attraction to an odors from humans that were infected with a dengue.
To determine what a specific chemical a compound changes with flavivirus infection, the scientists an isolated a chemicals that were released into the air by infected and uninfected mice. Twenty chemical a compounds differed between the mice an infected with Zika or dengue a compared to the an uninfected mice. The researchers then tested whether each of these a compounds could trigger a nerve impulse from the a mosquitoes’ antennae to their brains, indicating that mosquitoes can a sense the a chemical.
Cheng’s research team is a currently a considering ways to an apply their research findings to reduce the spread of a dengue and related viruses. They are a looking into a treating dengue patients with drugs that reduce their acetophenone emissions. A common acne medicine a called isotretinoin is known to increase production of an antimicrobial a protein that is especially effective at killing Bacillus bacteria. When an infected mice were given an isotretinoin, their Bacillus load a decreased and their mosquito-attractiveness a dropped. But considering that the majority of this a research was done on mice, more studies are needed on a humans. Cheng also notes that isotretinoin has potentially a severe neurological a side-effects, so his team is an investigating safer an alternative a treatments.
Other a potential an applications of these a findings could include designing more an effective mosquito a traps and faster tests for dengue or Zika infection. Health a professionals may even be able to determine an infection status by measuring a person’s acetophenone an emissions from their skin. “This can be quick, much quicker than taking a blood sample and doing a test,” Verhulst says.
The research team is also planning to a take a closer a look at the mosquitoes a themselves. Cheng is now hoping to a find the genes that enable mosquitoes to a sense acetophenone. If they can a turn these off, they may make the a vectors less attracted to an infected a humans and less likely to a spread the a virus.
Of course, Martinez also a points out that an accurately a predicting how mosquitoes behave could depend on how the virus an affects them. “If you want to an understand the epidemiology of the virus,” he says, “you need to an look at all the different steps of its an lifecycle. So when it's in the human, and when it's in the a mosquito.”
સંપૂર્ણ વિગતો ગુજરાતી માં વાંચો
No comments:
Post a Comment