mosquitoes kill more humans than anyother animal per year. and that includes other humans -- and we’repretty self-destructive. and now, mosquitoes arespreading the zika virus. [reactions splash intro] zika virus isn’t exactly new, and upuntil now, not exactly worrisome. it was first discoveredin 1947 in africa. typically only 1 in 5 peopleinfected actually get sick. the unlucky ones get mild symptomslike a fever, rash, and red eyes that usually last less than a week.
no biggie. but in 2015, zika, a relatively unknownvirus, began to spread explosively, affecting more than a millionpeople in brazil so far. and it’s a major health crisisbecause of its link to has to a 20-fold rise in brazil’s cases ofmicrocephaly, a condition that causes babies to be born withunusually small heads and often results in brain damage. to be clear, it is not yet known ifzika is actually causing microcephaly, but the increase in the zika casessuggests a strong link and
that is enough to cause alarm. as zika has spread, the world healthorganization declared it a global public health emergency -- a veryserious category which is reserved for explosive outbreaks like ebola. but unlike ebola, thezika virus has mostly spread via the dreaded mosquito bite. (so how do mosquitoes transmit disease?) mosquitoes, ticks, fleas, and otheranimals that carry diseases and infect other animals are called “vectors.â€
because vectors spread virusessomewhat randomly, they’re hard to predict, prevent and control,and only a few have vaccines (zika is not one of them). zika is carried by a specific speciesof mosquito (aedes aegypti) -- and only the female mosquitoes who needblood for their growing eggs. as she bites, she inserts a tubethat sucks up blood and another tube that sends saliva into the victim. their saliva has compounds that keepthe blood flowing, and prevent inflammation so you don’teven know you’ve been bitten.
inside a mosquito, viruses have tobe cunning -- they have to evade digestion and gut ph, pass throughseveral membranes, and fight off the mosquito’s immune defensefor long enough to get passed on to a more suitable host, sincethey can’t survive without one. as long as enough of the virus isn’teliminated, it gets passed on to humans via the mosquito’s transmission ofsaliva into a person’s blood stream. once inside humans, the virus canspread quickly from cell to cell, tricking healthy cellsto produce more viruses. so, the best way to not get adisease transmitted by a mosquito
is to simply not bebitten by one (#logic). (how do you not get bitten?) how, you ask? well, you hide from the mosquitoes. and we don’t mean shutting yourselfindoors all day everyday. you can use an insect repellant. the most common and effective repellentsare deet and products containing picaridin (pee-car-din), whichboth work the same way. mosquitoes have 72 types of odorreceptors in an antenna like
structure near their mouths(maxillary palp). 27 of them are dedicated tosniffing out a good human target. quick fun fact, studies have suggestedthat beer drinking, having o-blood type, being pregnant, and secretinglactic acid during a hard workout all make you more attractiveto types of mosquitoes that carry malaria or yellow fever. asides from those, mosquitoes lovethe scent of fresh carbon dioxide, which is unfortunate for all of thosewith functioning respiratory systems since we breathe out carbon dioxide.
we also breathe out another mosquito-attracting chemical called oc-tin-all. now what deet and picaridin do iscorrupt the mosquito’s odor receptors. they block their ability to detectcarbon dioxide, octenol and some of the other 400 compoundson your skin, making you essentially invisible to mosquitoes. picaridin is just a little bit better when it comes to mosquito repelling thandeet, and it’s less irritating on skin. however if you’re in a pinch you canalways use victoria secret’s bombshell. no, seriously. it’s proveneffective at repelling mosquitoes.
certain types of bug zappers pumpout carbon dioxide and octenol, tricking mosquitoes into thinkingthey’ve detected a tasty human and well, you know what happens after that. in light of this recent zika epidemic,scientists have been proposing some controversial ways to stop thespread of mosquito-borne diseases. these include ways of introducinggenetically modified mosquitoes into wild populations to sterilizemosquitoes, kill their offspring, or make them bad at transmitting disease. but before settling on any of thesemosquito options, officials have
asked people to protect themselves, and have even asked women to stop getting pregnant in some countries. so if you’re going outsideand you know there will be mosquitoes around, stay safe. make sure to put on some repellant. and hey, thanks for watching!
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