WEBVTT - Are Some People Immune To Mosquitoes?

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<v Speaker 1>Welcome to brain Stuff from how stuff works. Hey, brain stuff,

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<v Speaker 1>it's Christian Seger. If you're like most people, you hate mosquitoes.

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<v Speaker 1>They're kind of the Andy Dick of the insect world,

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<v Speaker 1>annoying and in some cases dangerous. If we rate animals

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<v Speaker 1>by the number of deaths they cause, these little blood

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<v Speaker 1>suckers top the charts by a wide margin, and this

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<v Speaker 1>is due to their transmission of malaria and other harmful diseases.

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<v Speaker 1>And whether your next mosquito bite causes serious illness or

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<v Speaker 1>intense frustration, we can all agree mosquitoes are just the worst.

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<v Speaker 1>But are some people immune to mosquito bites? First, let's

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<v Speaker 1>be clear mosquito bites aren't actually bites. When a mosquito

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<v Speaker 1>lands on you, she uses her probosis. It's a long,

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<v Speaker 1>double tubed mouthpiece to pierce your skin and get at

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<v Speaker 1>the blood underneath. And yes, that's a sheet. Every single

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<v Speaker 1>mosquito that has ever bit you has been female. They

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<v Speaker 1>bite you because they need a protein in your blood

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<v Speaker 1>to develop their eggs. When a mosquito uses her antenna

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<v Speaker 1>to sense the warm blood beneath your skin and then

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<v Speaker 1>pops her probosis in to tap your capillaries. One of

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<v Speaker 1>those tubes injects saliva, while the other one withdraws blood.

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<v Speaker 1>The saliva contains enzymes that act as a mild painkiller

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<v Speaker 1>and thins the blood to prevent clotting. Your body interprets

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<v Speaker 1>these enzymes as foreign invaders and produces histamine. Histamine binds

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<v Speaker 1>to receptors in the bite area, dilating local blood vessels.

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<v Speaker 1>This increased blood flow summons more white blood cells, and

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<v Speaker 1>when you get too much histamine, the bite area can

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<v Speaker 1>swell and redden, creating what's called a wheel. Yeah, wheel,

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<v Speaker 1>that's the word of the day. Now, each person will

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<v Speaker 1>react to a bite differently, and your allergies will vary.

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<v Speaker 1>So what makes a mosque to choose a certain person, Well,

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<v Speaker 1>there are a number of factors, one of the biggest

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<v Speaker 1>being that there are more than three thousand known varieties

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<v Speaker 1>of mosquitoes and they're not all looking for the same thing.

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<v Speaker 1>For those that dig a nice sip of human blood, smell,

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<v Speaker 1>body temperature, and genetics play huge roles. According to scientists

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<v Speaker 1>at Rotterdam Research, each human body can produce anywhere from

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<v Speaker 1>three hundred to four hundred distinct chemical odors, some of

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<v Speaker 1>which are bug magnets and others they might be bug repellent.

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<v Speaker 1>Research from a chemist named Ulrich Berner shows that mosquitoes

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<v Speaker 1>are particularly fond of carbon dioxide that's released from exhalation

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<v Speaker 1>and the skin, and they also like lactic acid, which

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<v Speaker 1>is present on our skin after exercise. Now, drinking beer,

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<v Speaker 1>being pregnant, and being a bigger person can all also

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<v Speaker 1>make you more active to mosquitoes. Diet and blood type

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<v Speaker 1>surprisingly don't seem to matter so much. Everybody has these

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<v Speaker 1>yummy chemicals on their body, but it seems that the

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<v Speaker 1>people mosquitoes avoid produced higher amounts of repellent chemicals. Dr

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<v Speaker 1>James Logan from Rotterdam set up a pretty weird experiment

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<v Speaker 1>to see if he could find these all important repellent chemicals.

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<v Speaker 1>His team separated people into two groups, mosquito favorites and

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<v Speaker 1>mosquito mez. They put these folks in body size foil

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<v Speaker 1>bags to collect their odors for two hours, and they

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<v Speaker 1>used a chromatograph to analyze the chemicals they had collected

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<v Speaker 1>and hooked electrodes up to mosquito antenna to see what

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<v Speaker 1>the bugs thought of each smell. They found about seven

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<v Speaker 1>or eight made a difference. These odors were present insignificantly

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<v Speaker 1>different quantities between those people who were attractive to mosquitoes

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<v Speaker 1>and those who weren't. Their study, published in the Journal

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<v Speaker 1>of Medical Entomology, cited two chemicals as significantly repellent, one

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<v Speaker 1>called six methyl five hepton to one, which apparently smells

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<v Speaker 1>of nail polish remover, and another called jennal acetone, which

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<v Speaker 1>has a kind of floral odor. As of this recording,

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<v Speaker 1>the race to use these and other chemicals as a

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<v Speaker 1>new superbug repellent is in full swing. So you probably

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<v Speaker 1>know that bacteria is largely responsible for the various smells

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<v Speaker 1>of the human body. Each human being is home to

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<v Speaker 1>a unique mix of trillions of microbes. It's sort of

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<v Speaker 1>like a fingerprint. Now, our genes may play a large

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<v Speaker 1>role in determining what sort of microbial life forms we

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<v Speaker 1>end up posting in. A team led by doctor Manuela

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<v Speaker 1>Fernandez Grandin tested the heritability of attractiveness to mosquitoes using twins.

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<v Speaker 1>The twins would put a hand into either end of

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<v Speaker 1>a sealed dome along with twenty female mosquitoes. Now don't worry,

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<v Speaker 1>they weren't allowed to bite. Researchers gave each subject an

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<v Speaker 1>attractiveness score compared to the other hand, identical twins had

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<v Speaker 1>consistently more similar scores compared to fraternal twins, so jeans

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<v Speaker 1>do seem to play a role. This may be tough

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<v Speaker 1>news for the or so of people that mosquitoes find

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<v Speaker 1>particularly attractive. If you're one of the local mosquito's favorite dishes,

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<v Speaker 1>remember to keep some kind of bug repellent with you

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<v Speaker 1>and to wear long sleeves and pants if the weather allows,

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<v Speaker 1>especially in areas of the world where these bugs carried

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<v Speaker 1>diseases like malaria or denge. And I suppose there's a

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<v Speaker 1>little light at the end of this mosquito net tunnel here.

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<v Speaker 1>Some people do have a chance of building up a

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<v Speaker 1>tolerance after repeated mosquito bites, but for others, the allergy

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<v Speaker 1>just gets worse. Check out the brainstuff channel on YouTube,

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<v Speaker 1>and for more on this and thousands of other topics,

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<v Speaker 1>visit howstuff works dot com.