Thursday January 17, 2019

Decoded: Why Mosquitoes Bite You

For the study, published in the journal Current Biology, the team placed mosquitoes in an insect flight simulator and exposing the mosquitoes to various smells, including human body odors, and observed how the insects, trained or not, reacted

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The study dopamine -- a brain chemical involved in reward learning -- is a key mediator of aversive learning in mosquitoes. Pixabay
The study dopamine -- a brain chemical involved in reward learning -- is a key mediator of aversive learning in mosquitoes. Pixabay
  • People who swat at mosquitoes or perform other defensive behavior may be abandoned, no matter how sweet
  • The team placed mosquitoes in an insect flight simulator and exposing the mosquitoes to various smells for the study
  • The study was published in the journal Current Biology

Wonder why you receive more bug bites than others around you? It is because, mosquitoes can rapidly learn and remember the smells, researchers have found.

The study dopamine — a brain chemical involved in reward learning — is a key mediator of aversive learning in mosquitoes.

However, people who swat at mosquitoes or perform other defensive behavior may be abandoned, no matter how sweet.

Dopamine modulates the neural activity in the brain region where the information on smell in such a way that odors were easier to discriminate, and potentially learn, by the mosquitoes, the researchers said. Pixabay
Dopamine modulates the neural activity in the brain region where the information on smell in such a way that odors were easier to discriminate, and potentially learn, by the mosquitoes, the researchers said. Pixabay

ALSO READ: $18 Million Donation to Target Mosquito-borne Diseases like Zika in Colombia and Brazil

Mosquitoes exhibit a trait known as aversive learning by training female Aedes aegypti mosquitoes to associate odors (including human body odors) with unpleasant shocks and vibrations, said Clement Vinauger, Assistant Professor in Virginia Polytechnic Institute and State University or Virginia Tech.

For the study, published in the journal Current Biology, the team placed mosquitoes in an insect flight simulator and exposing the mosquitoes to various smells, including human body odors, and observed how the insects, trained or not, reacted.

“Unfortunately, there is no way of knowing exactly what attracts a mosquito to a particular human — individuals are made up of unique molecular cocktails that include combinations of more than 400 chemicals,” said Chloe Lahondere, Assistant Professor at the varsity.

“However, we now know that mosquitoes are able to learn odors emitted by their host and avoid those that were more defensive,” Lahondere added.

ALSO READ: Dengue stings Delhi as govt sleeps under an opaque mosquito net

Aedes aegypti mosquitoes are vectors for Zika fever, dengue fever, chikungunya, and yellow fever viruses, and can be found in tropical and subtropical regions throughout the world. Pixabay
Aedes aegypti mosquitoes are vectors for Zika fever, dengue fever, chikungunya, and yellow fever viruses, and can be found in tropical and subtropical regions throughout the world. Pixabay

 

“Understanding these mechanisms of mosquito learning and preferences may provide new tools for mosquito control,” Vinauger said.

“For example, we could target mosquitoes’ ability to learn and either impair it or exploit it to our advantage,” he noted. (IANS)

Next Story

Research for Vaccination Should Include Pregnant Women: Experts

Pregnant women are continuously getting left out of the benefits of scientific advancement in medicine

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Ebola, pregnant women
A Congolese health worker administers Ebola vaccine to a woman who had contact with an Ebola sufferer in the Democratic Republic of Congo, Aug. 18, 2018. VOA
 Pregnant women have been systematically overlooked in the development and deployment of new vaccines, undermining their health and their communities’ safety, according to guidelines released this month by an international team of researchers, scientists and health care providers.

The report, developed by the Pregnancy Research Ethics for Vaccines, Epidemics and New Technologies (PREVENT) working group, identifies a cycle of exclusion that prevents pregnant women from accessing the benefits of vaccines.

“There’s a lot of reticence to include pregnant women in research,” said Carleigh Krubiner, the project director and a co-principal investigator for PREVENT.

And that’s led to a shortfall in data about how pregnant women respond to vaccines.

Krubiner, an associate faculty member at the Johns Hopkins Berman Institute of Bioethics, told VOA that researchers and health care providers tend to exclude pregnant women from trials, vaccinations and tracking because they lack evidence of the risks expectant mothers face.

“We continue to have this Catch-22 of not having enough evidence to feel like we can do the research. But if we don’t do the research, we don’t have the evidence,” Krubiner said.

Women. Pregnant Women
Nicole Andreacchio, second right, who is seven months pregnant waits in line to receive the swine flu vaccine from the Montgomery County Health Department at Congregation Beth Or in Maple Glen, Penn. VOA

There’s a lot of fear’

Concerns over “theoretical harm” drive decisions to exclude pregnant women from interventions, Krubiner said. But the data scientists do have, often from women not known to be pregnant when they received vaccinations, suggest those concerns are overblown.

In the case of rubella, for example, a contagious viral infection, researchers didn’t find a connection between congenital rubella syndrome and the vaccine when thousands of pregnant women were vaccinated before their pregnancy status was known.

“There’s a lot of fear,” Krubiner said. “And there are certainly biologically plausible risks associated with different types of live replicating viral vaccines.”

Live-virus vaccines contain a weakened version of the disease designed to stimulate an immune response in recipients.

“Very often, the benefits of vaccinating do still outweigh the theoretical, or even real harms that may be posed to the fetus,” Krubiner said.

One vaccine known to cause harm to pregnant women and their fetuses, Krubiner added, is for smallpox. But even in that case, she said, if a threat were imminent, pregnant women should get vaccinated, given the seriousness of the disease. The Centers for Disease Control and Prevention support that guidance.

pregnant women
A nurse holds a vial of measles, mumps and rubella vaccine at Boston Children’s Hospital in Boston, Feb. 26, 2015. VOA

‘Strongly recommended’

The advice pregnant women receive about vaccination should reflect what’s known about the particular vaccine and the specific circumstances of the outbreak, Krubiner said.

Recommendations should follow current knowledge about the disease in question, the severity of the threat, and the likelihood of exposure, she added.

But the general guidance is unambiguous.

“At minimum, vaccines should be offered to women, and in many cases they should be strongly recommended,” Krubiner said.

Among those cases is the vaccine for seasonal and pandemic flu, which pregnant women should be urged to receive, in light of the severity of the risks tied to infection — not just for the expectant mother, but the future child as well.

Pregnant women should also be encouraged to receive vaccines for H1N1, also known as swine flu, and DPT, which protects against diphtheria, whooping cough and tetanus.

Pregnant Women
More complex data collection will paint a more complete picture. Pixabay

Institutional change

Involving pregnant women in the benefits of vaccines will require systemic shifts, the PREVENT group said in its report this month.

An important step is to become more proactive in bringing pregnant women into what Krubiner called the “development and research pipeline.” By involving pregnant women early, she said, health care providers aren’t left with the kinds of blind spots about how vaccines will affect expectant mothers and their fetuses that lead to their exclusion.

Even basic information, such as pregnancy status in case reports, sometimes goes untracked, despite being easy to collect and providing insight into the unique burden pregnant women face in disease outbreaks.

More complex data collection will paint a more complete picture. Specific studies could be designed to examine the safety and efficacy of vaccines for pregnant women, for example, or to track effects at different points in gestation.

“Starting anywhere at this point would be better than the dearth of data that we have right now to really try to address the needs of pregnant women and their babies,” Krubiner said.

Pregnant women
There’s a lot of reticence to include pregnant women in research. Pixabay

Lessons learned

Disease outbreaks devastate communities. But they also provide opportunities to better prepare for, and respond to, the next epidemic.

In this year’s Ebola outbreaks in Congo, responders have applied lessons from West Africa’s 2014-16 epidemic to community engagement. And drug trials toward the end of the West Africa outbreak produced evidence about the vaccine that’s now being deployed.

But pregnant women weren’t included in those trials, and researchers collected little in the way of data about the burden pregnant women and their offspring face.

Also Read: Women Hit Especially Hard In Congo’s Worst Ebola Outbreak

“Pregnant women are continuously getting left out of the benefits of scientific advancement in medicine,” Krubiner said.

“If we continue to fail to collect the kinds of data that we need, to generate the kind of evidence that we need and to also have interventions that meet the broader population’s needs,” Krubiner said, “then we’re just going to continue to perpetuate the cycle.” (VOA)