Articles, Blog

Zika Virus: What We Know (And What We Don’t)

December 21, 2019

(intro) What we don’t know is often scarier than what we do, especially when it comes to public health. And earlier this week, the World Health Organization declared an international public health emergency over the Zika virus, which, in it’s words, is spreading explosively across Central and South America. Now, if there are three words you never want to hear in the same sentence, they are probably “virus”, “emergency” and “explosively”. But there is a lot we still don’t know about Zika, and scientists are in a hurry to learn as much as they can. Because while this virus has been fought for decades to be practically harmless, it may turn out to be responsible for a rash of serious birth defects. So here’s what we know so far. Zika is a virus named after the Zika forest in Uganda where it was discovered in 1947. It’s from the family of viruses known
as flavivirus which also includes dengue, Yellow fever and West Nile virus, none of
which are at all pleasant. But infection with Zika seems most often to create little more than mild flu-like symptoms if any at all. It’s spread by a certain kind of mosquito known as Aedes, tropical bloodsuckers that spread other flaviviruses. And for decades, Zika has been circulating around parts of Africa and Asia, but it didn’t appear to be doing much damage. People who were infected would come down with a mild fever, a rash, maybe a headache, but that was it. Up to 80% of people showed no symptoms at all. So it’s been thought that a stable relationship was struck between human, mosquito and virus. People who were infected at an early age suffered mild illness and then developed immunity before they were old enough to get pregnant.
Then all of a sudden in 2007, the virus moved. There was a Zika outbreak on Yap, an isolated set of islands in the southwestern Pacific. Nearly three-quarters of the population were infected. But again the results were mild and nobody died or was even hospitalized. Then, in November 2015, health officials in Brazil raised alarm about a worrying trend. Last year, nearly 4,000 babies were born with extremely small heads, a condition known as microcephaly For each of the previous five years,
this number was more like 150. And this was bad news. If babies do
survive being born with microcephaly, they can suffer severe physical and
learning difficulties their whole lives. Now many things can cause microcephaly, including genetics and malnutrition and heavy alcohol use during pregnancy. But none of these things could explain Brazil’s
sudden increase in birth defects. What was new to Brazil that year was Zika,
first detected there in May 2015, but largely ignored. There was no reason to suspect it, but tests on a handful of pregnant women with affected babies revealed the presence of RNA from the Zika virus. Now it’s not certain that
Zika and microcephaly are related, but new evidence is coming in almost daily and as of now officials are assuming that they are related. Unfortunately there is no vaccine for Zika and it could take a decade to develop one. As a result, advice from the Centers for Disease Control and Prevention is based entirely on
avoidance and vigilance. For example, women who are pregnant or think they may be, should avoid any of the 26 countries where Zika is active, mainly in
Central and South America. And those already living there should do whatever possible to avoid mosquito bites, like using repellent, wearing long sleeves and trousers, and removing standing water where the mosquitoes breed. In the meantime, researchers are working to clear up many things about Zika that we don’t know.
Like was causing microcephaly all along in Africa and the South Pacific and it
just wasn’t reported? Or is there something different about the virus in Brazil, or the way it interacts with people there? While doctors tackle those questions other scientists are focused on stopping the spread of the virus. The Aedes mosquito lives mainly in tropical and subtropical regions and it’s not likely that it will ever leave that range.
The main worry is that the virus will find a different way to
get around or mutate into an even more dangerous form like the West Nile virus
did back in the nineties. Viruses are master mutators and humans are master travelers, both of which could help Zika spread. Some experts think Zika came to Brazil
around the time of the 2014 World Cup, among the thousands of traveling sports fans. And this summer Rio is hosting the Olympic Games, so it seems like we have a lot to learn in very little time. Thanks for watching this episode of SciShow news, and thank you especially to all of our Patrons on Patreon, who make this show possible. If you want to help us keep making videos like this, you can go to, and don’t forget to go to and subscribe.


  • Reply Jerk March 12, 2016 at 1:05 am

    health officials and the World Health Organization are denying links
    between a well-known pesticide and microcephaly, a condition that causes
    babies to develop abnormally small heads and leads to death in some
    cases.The pesticide is called Pyriproxyfen, and it's used in water tanks to eliminate mosquito larvae. A
    group of doctors from Argentina claims this larvicide could be behind
    the recent surge in babies born with microcephaly in Brazil. Based on
    this claim, Rio Grande do Sul, Brazil's southernmost state, has decided
    to ban the larvicide.

  • Reply Jerk March 12, 2016 at 1:07 am

    This is a really good one!!

  • Reply Jerk March 12, 2016 at 1:23 am

    Yes I am posting in annoying fashion but If I can wake up even just one of you, that's important to me. <<<<————

  • Reply Jerk March 12, 2016 at 1:35 am

    Hey everyone! we can rest assured its not the chemicals they put directly into the drinking water because WHO, Brazilian authorities and the Pyriproxyfen’s Japanese manufacturer, Sumitomo Chemical all said that it super safe and awesome stuff, So we can trust them. And if you do then I have a bridge I want to sell you for a great deal.

  • Reply Jerk March 12, 2016 at 1:45 am
    Abrasco’s report makes clear that in the regions where microcephaly is a problem, pyriproxyfen is just the tip of the iceberg. The people, particularly the poor, are being poisoned via multiple sources, with multiple chemical agents.
    The report says that the widespread application of toxic insecticides and larvicides – sometimes in drinking water – has compromised people’s immune system by increasing their toxic load.
    For example, Abrasco points out that an
    organophosphate insecticide, temephos (commercially known as ABATE®) was introduced in Brazil in 1968 as a larvicide in drinking water, especially in North and Northeast Brazil. Impacts on people's health have not been studied, according to Abrasco. The authorities continued to use it in spite of the fact that the mosquitoes have developed resistance.

  • Reply Marco Polo March 13, 2016 at 1:37 pm

    Another big worry, is it a synthetic genetically modified form of the original virus. And what are the implications if this is found to be true.

  • Reply Cpt Red March 16, 2016 at 11:12 pm

    When you Wrote zika on Google Theres a Giant Ad's About it !
    Another New world Order Disease …
    1981 – Aids
    1996 – Mad Cow
    1999 – Anthrax
    2000 – West Nile virus
    2003 – H5N1
    2009 – H1N1
    2015 – Zika
    Chemical Weapon
    any toxic chemical or its precursor that can cause death, injury or temporary incapacitation use to reduce Mass population.

  • Reply susynoid March 20, 2016 at 7:13 pm

    I read that there is no substantial link between Zika and Microcephaly. Can anybody verify that Colombia has had the most cases of Zika, but no cases of Microcephaly? Also, that a third of all recent Microcephaly cases were found in one area of Brazil?

  • Reply Malik Dady March 25, 2016 at 1:44 am

    I think we should watch the Simpsons more so we know what to predict.

  • Reply Prafulla March 25, 2016 at 1:32 pm

    why does thymus keeps on reducing its size as we go older?

  • Reply Freddy Mapp March 31, 2016 at 1:59 pm

    I work in the field .I am reaching out to everyone Trying to get pledges in support of a science crowd sourcing thing I am doing to support my research. If you are intrested in pledging that would be great. Any amount would help .

  • Reply Meph April 3, 2016 at 6:30 pm

    Are there good diseases?(helpful for survival)

  • Reply Michael Sharkawy April 6, 2016 at 7:34 am

    crap I live in Egypt where the zika virus is located

  • Reply Michael Sharkawy April 6, 2016 at 7:35 am

    crap I live in Egypt where the zika virus is located

  • Reply BoodleBops April 6, 2016 at 8:09 pm

    woah theres a girl at my school with microcephaly

  • Reply serve24 April 12, 2016 at 11:33 pm

    How can we know that Zika and microcephaly is not just a correlation and not a causation? I mean, I'm fine with playing it safe, but let's not forget science!

  • Reply CandyThrillZ April 15, 2016 at 8:28 pm

    MUM: GOD i told u when u play plague inc it really happens GOD: who cares get out of my room mum!

  • Reply DJ TigerSt April 18, 2016 at 12:16 am

    Oh god my brothers wife I pregnant and I live where those fuckers are… I hope she doesn't get bit.

  • Reply DJ TigerSt April 18, 2016 at 12:17 am

    +100 points…. Unclock total organ failure.

  • Reply Jeffery Thomas April 18, 2016 at 10:42 pm

    In the movie World War Z, the soldiers helping B Pitt's character get to the plane called the zombies Zikas. Check it out.

  • Reply marcus24000 April 27, 2016 at 12:44 pm

    wel oke a virus that breaks out and is transmited through muskito's meaning it started somewhere with humans wel oke. what i find odd however is they never explain where it comes from it just "popped up" and second the only way humans can pass it on so far as by sex,wel these 2 things make me think it might be made or enhanced.changed  in a lab,we known for a while that people and goverments talk about population controle and we also know wel these who do research know that serten viruses where made in labs.

  • Reply PenguinRX May 2, 2016 at 8:23 pm

    Who's playing plague inc again

  • Reply Ian 64 May 7, 2016 at 2:51 am

    if zika is transmitted by mosquitoes then it may just be some kind of protozoan and not a virus

  • Reply Creeper Guardian May 7, 2016 at 10:44 am

    3,382,309th sub

  • Reply Matthew Reagan May 7, 2016 at 12:46 pm

    Thank you Patrons for helping to bring this show to all of us scummy not Patrons.

  • Reply Jonathan Zhou May 11, 2016 at 4:45 am

    Zika is already in America. I come from Minnesota and it's already down in southern Minnesota

  • Reply mhud May 14, 2016 at 1:38 am

    we are playing plague.Inc REAL LIFE EDITION

  • Reply Scratch Tshirt May 16, 2016 at 1:40 pm

    yes sure we should trust in WHO, like hiv aids.

  • Reply egotomy hib May 19, 2016 at 8:10 pm

    Nature didnt make this Virus,only humans do this.

  • Reply Cupcakemuffin X May 20, 2016 at 12:21 am


  • Reply Marvin's Reviews ETC. May 20, 2016 at 11:27 pm

    population control

  • Reply Jay Ed May 21, 2016 at 5:23 am

    Wow… So just avoid pregnancy for 10 years??? Really??? Try telling people to stop travelling is like telling a young adult stop smoking. We R DOOMED.

  • Reply Jay Ed May 21, 2016 at 5:31 am

    We doomed because a prehistoric virus is going to come from glaciers melting and the heating up of the planet. Best believe a strong enough strand of virus that's been around longer than us will be too strong for cdc to control resulting in another world wide plague.

  • Reply SonicXRage May 28, 2016 at 3:27 am

    Wow, I didn't expect people to be talking about Plague Inc. so much. I thought it was eradicated since a few years back.

  • Reply טימור חורשין May 29, 2016 at 8:05 pm

    safe yourself !!!

  • Reply Simply Stressed May 30, 2016 at 8:25 pm

    My mom has been freaking out by this virus

  • Reply Rod Gossett June 2, 2016 at 3:17 pm

    You have to be as dumb as a stack of heavy bricks to not know the American CDC/US health Dept. & the W.H.O use propaganda to procure founds($$$$$$) for their NEVER ending Nazi experiments. I grew up in Florida in all of the sixties around mosquitoes, and I am still alive no defects other than the US Health Dept's childhood shots. Stop buying the propaganda. Once these health Nazis get their founds it will be something new, every year.  Read the book "Bad Blood" on the US Health Dept. today's CDC. Stop buying their tricks.

  • Reply DeadlyDanDaMan June 4, 2016 at 4:33 pm

    "Unlikely to leave those regions…" Annnnnnnnnd they just found it in New Jersey. GG Mosquitoes.

  • Reply Joe Man June 5, 2016 at 2:30 am

    What of Oxitec? Any word from them?

  • Reply wheting hsiao June 6, 2016 at 3:41 am

    To prevent zika mosquito maybe you can use sea water into the ditch. It's work in a week.

  • Reply wheting hsiao June 6, 2016 at 3:46 am

    The sea water solve zika mosquito that is work in Kaohsiung of Taiwan.

  • Reply Kosher puppet Xi Jinping June 6, 2016 at 2:57 pm

    The Rockefeller Foundation owns the patent for the Zika virus.

  • Reply Legal Tender June 10, 2016 at 2:31 am

    Can you guys cover the hypothesis that the sruge of microcephaly cases might be caused by massive amoounts of insecticide dropped in the water to prevent zika? caused

  • Reply Amit Mate June 13, 2016 at 3:54 am

    Mr. Green Zika is not active in India.

  • Reply David Theel June 17, 2016 at 7:58 pm

    I would like to see a proper date, properly visible. Scary Bad Virus. Wish to continue use in future to show progress. With Hope and Many Supported Well, as with you, this is a dead end project for me. I have fear here. Wish to remain concerned, with Faith. This world can be cruel.

  • Reply Rob Walker June 22, 2016 at 5:12 am

    how do you know what you don't know????

  • Reply J, Ludwig June 23, 2016 at 12:24 pm


  • Reply Suh Dude June 26, 2016 at 10:11 am

    Virus emergency trump

  • Reply Nick Bjerg Jensen July 5, 2016 at 11:01 am

  • Reply DeWafflez July 20, 2016 at 12:08 pm


  • Reply iwilleatyourmother July 24, 2016 at 4:57 pm

    Three words put together Im scared of are "Donald, Trump, President"

  • Reply Show Your Skills July 29, 2016 at 2:37 pm

    it's in Florida

  • Reply teppolundgren August 4, 2016 at 4:29 am

    Who cares about Zika? What's the problem?

    If you don't live in a place where those mosquitoes exist, but you're visiting one, just don't have sex.
    And if you do get the virus, just abstain from having sex for 6 months. Don't be so fucking weak-minded!

    And if you're pregnant, don't go to those places at all. Watch the Olympics on TV, you idiots.

    If you live in one of the affected areas, use protection if you have to fuck someone, and never get pregnant.


  • Reply Maha Khader August 6, 2016 at 3:56 am

    there's zika virus in Florida…..and I live in Florida?????

  • Reply Azul Monster August 11, 2016 at 4:55 am

    if you are there me and my family are dieing goodbye.

  • Reply Andreas Loch August 12, 2016 at 2:56 pm

    Stop Zika Virus

  • Reply Nau seous August 13, 2016 at 3:58 am

    Cause of ZIKA virus, isn't Zika it's pesticides, it's Monsanto!

  • Reply East to Central Midwest Publishing America August 15, 2016 at 2:36 pm

    Known………………… for decades? Realy? That long

  • Reply friendsgameplay August 19, 2016 at 8:06 pm

    my best friend's mom is pregnant and zika was very bad there is am sooo worried

  • Reply DrumStick August 27, 2016 at 12:11 am

    if u get infected,will it affect your future children?im 14 sooooo…i wouldnt be so worried if its treatable.

  • Reply *InsertNameHere* August 27, 2016 at 4:11 pm

    I live in Florida I can't find mosquito repellent in Walmart. Time to look up a video

  • Reply Dill Pickles August 29, 2016 at 2:46 am

    Thanks for the info!

  • Reply Reyner Giovanni August 31, 2016 at 5:19 am

    damn Olympic!!!

  • Reply Liou David September 1, 2016 at 5:09 am

    So you basically gain immunity after being infected and fought off the virus?

  • Reply none None September 1, 2016 at 9:06 pm

  • Reply Yu-Shan Lim September 2, 2016 at 10:27 pm

    Zika patients may not have any symptoms.. So is that good or bad? The virus won't kill you from inside right?

  • Reply Zara Coulston Williams September 6, 2016 at 11:07 am

    Explosive Virus Emergency – worst headline ever

  • Reply Davtd Lowe September 8, 2016 at 12:03 am

    MATTERS NOT WHAT YOU'RE TOLD, HOPE YOU FIGURED THAT PART OUT BY NOW. since 2011 Mar, America,Japan and i hope your catching on. the earth, yes oceans also. have been doused in radiation from fukushimas 800 tons of weapons grade mox fuel.. YOUR hero hillary raised the amount of radiation YOUR CHILDREN AND you could absorb. OBVIOUSLY THE FASTEST GROWING ORGANISMS WILL MUTATE FASTEST.. YES babies in the womb.. your about to witnesses an unstoppable CATASTROPHIC die of. you may not see it at first. but that's our fault.. IT will be blamed on50 different reasons. Still enough of you will see.. have a beautiful day. love your FUCKING children morons.. LEAVE NO AUTHORITY EXISTING NOT RESPONSIBLE TO THE PEOPLE

  • Reply debra athanas September 9, 2016 at 4:15 am

    Just recently I read that the zika virus was patented by the Rockefeller foundation in 1947 placing that info on the back burner just to see how things play out with this world wide "epidemic" I have kept watching. These things usually come in more pervasive acts.
    1 identify the fear. and warn the public.
    2. build on it, make it seem worse than it is
    3 get other government agencies involved
    4. Create a vaccine make it available to the public
    5. harness gov agencies to propagandize, fears and treatment and make it mandatory
    6. whoops some people die due to collateral damage mercury poisoning.

    If you don't believe me today I watched a news video from the weather channel saying the Rockefeller foundation says the zika virus effects adult humans like mental illness. Next they will have the vaccine and before you know it we will all be lined up to take their cocktail poison once again. That is all of you I am not taking anything. Maybe not you now that you have the truth unless you don't believe me!

    Oh and by the way these are the same gov agencies who silenced the truth about Fukushima until they can't keep it a secret anymore. All 3 reactors have had a melt down and the is radiation leeched into the ocean that is why the sea life is dying. It has reached the north American coast and radiation is evaporating into the atmosphere from the pacific. No more pacific, sea salt, fish, sushi or salmon or shell fish it is all contaminated as is the water at the beach!

  • Reply Shunya September 9, 2016 at 1:52 pm

    Lol Zika is not in India , your misrepresenting situations .

  • Reply Araragi Koyomi September 28, 2016 at 2:45 pm

    Plague Inc. Now it makes sense

  • Reply Cherry Lasting October 14, 2016 at 5:49 pm

    Damn these mosquitoes are at it again.

    Why don't we all light some citronella candles? And put on some citronella perfume, and plant some citronellas

    Maybe bug bomb entire countries with citronellas??

    Well now all I have to worry about is the spread of the decease.

  • Reply andrew langham November 18, 2016 at 5:40 am

    2 grams of Bovine Lactoferrin oral capsules per day for 12 months clears
    all viruses from neurons' is safe during pregnancy but every medical
    establishment' drugs companies' Chief medical officers'' GP's entire
    press & media have totally shunned this research which was carried
    out by Alexander Fleming' Dr Florey at Oxford and retrived and evaluated
    again by myself; Please could you enlighten me as I am greatly
    perplexed and dissappointed that the human race can be so' ……..words
    here now fail me' Many thanks' andrew langham' Burton on trent UK
    date;- 16 Nov 2016

  • Reply Lola True November 23, 2016 at 8:14 pm

    i got zika last year. on christmas day in Barbados I went to the hospital. they didn't know what i had and thought it was dengen's fever. i got a horrid red rash spreading down my body, but recovered after a week. thank god i wasn't pregnant.

  • Reply FRISHR January 10, 2017 at 12:52 am

    Good thing my country will never host an olympic! 😀

  • Reply Johan Rodriguez March 13, 2017 at 5:27 pm

    Zika is in the U.S too, just saying

  • Reply Kevin March 18, 2017 at 5:33 am

    How bout big heads

  • Reply 4LIENW4RE April 15, 2017 at 10:21 pm

    I hope you catch zika when your wife gets pregnant

  • Reply Bryan Merrill April 19, 2017 at 3:23 pm

    1:11 – 2:04
    What an insidious virus…

  • Reply andrew langham April 28, 2017 at 7:59 am

    Ivermectin kills the zika virus yellow fever' and chikungunya in vivo but is not safe during pregnancy

  • Reply andrew langham May 8, 2017 at 1:49 pm

    Transforming growth factor-beta 2 (TGF-β2) wolbachia affects this cytokine by switching off cif A genes; fact; causes microcephaly and many other problems' such as makes dengue and west nile' malaria far more dangerous' fact;

  • Reply Adrian Thomson June 6, 2017 at 8:36 pm

    Zika virus infection in pregnancy causes severe disability in babies by attacking stem cells in the developing brain.
    In adults, where the brain is fully developed, Zika usually causes no more than mild flu-like
    One occasion when neuro stem cells are in the adult brain is in glioblastoma, which is a common and usually fatal form of brain cancer.

    Zika virus is now going to be investigated as a potential an oncolytic virotherapy for treating glioblastoma, where the virus will infect and kill the cancer cells in the brain.

  • Reply вlσѕѕσm_ ѕuвlímínαlѕ June 18, 2017 at 3:44 pm


  • Reply McLovin the Walrus July 14, 2017 at 4:13 am

    i had zika before, the rash was annoying along with the fever.

  • Reply David Kolb August 2, 2017 at 10:15 pm

    "Zika must evolve to kill"- plague inc

  • Reply Its_ JP August 24, 2017 at 6:37 pm

    Develop a bio-chemical weapon and kill off the species.

  • Reply Sancho piment September 1, 2017 at 7:39 am

    zika is good for the future it can regulate the population we don't need a vacin. you know why virus are existing for regulate a species so i think this time the medicine mustn't create a vacin even more modify the virus for a better effect .

    don't forget more people more some need's planet earth don't need humanity.

  • Reply dolphintattoogirl November 14, 2017 at 11:18 am

    The Aedes genus is NOT the only genus of mosquito that can carry it. The Tiger Mosquito of Isreal can carry it too; and many other species are also potential carriers.

  • Reply dolphintattoogirl November 14, 2017 at 11:22 am

    To answer 1 of your questions, a group of scientist in China found out that The Zika Virus underwent a few key mutations in 2013 that made it very dangerous. Is Zika lytic or lysogenic? That is what the world needs to know.

  • Reply Sophester Animates January 7, 2018 at 8:31 am

    I've never been bitten by a mosquito no joke.

  • Reply Danielle Wilson February 4, 2018 at 1:23 am

    If viruses are classified into families why aren’t they on the tree of life when they can reproduce mutate and respond to environment

  • Reply Josh Marcum March 29, 2018 at 6:34 am

    Somehow the mosquitos survive with it.

  • Reply Current Cuba May 28, 2018 at 12:48 am

    keep updated on the zika virus at

  • Reply Yan Meng June 14, 2018 at 3:51 am

    DuoSuccess TCM Prevent and Cure Epidemic Diseases 。

  • Reply Lullaby Angel July 28, 2018 at 12:51 pm

    Reminds me of plague inc

  • Reply Lullaby Angel July 28, 2018 at 12:57 pm

    World Cup:Hey Zika
    Zika virus:hey
    World Cup:I’m being hosted in your faveriote climate
    Zika virus:OMG
    World Cup:It’s in Brazil wanna come despite knowing you’ll kill everyone
    Zika virus:YES ???

  • Reply panda is angrey August 24, 2018 at 3:29 am

    I thought it gives you powers

  • Reply Edyta November 16, 2018 at 6:12 pm

  • Reply aeiou December 27, 2018 at 12:38 pm

    Good informational video. Learn something new everyday.

  • Reply NKVD Citizen101 June 4, 2019 at 9:56 pm

    something must have triggered the virus to be activated, would want to know what kind of vaccinations that where taken before zika blossomed in south america.

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