Why Can Mosquitoes Transmit Zika, But Not the Flu?


Are you like most humans?
Do you hate mosquitos? We talk about mosquitos a lot because
they’re terrible. They transmit malaria, West Nile Virus, and now the Zika virus among many other pathogens. But what’s so special about those diseases that we only get them from mosquito bites? Why can’t we get other diseases from
mosquitoes? Like if you have the flu and a mosquito bites you and then bites someone else, why don’t they get the flu? Well, the disease-causing organisms that
mosquitoes transmit to humans are actually special cases. They evolved to
both require an insect and a vertebrate as a part of their life cycle. In fact,
this requirement is so specific that each disease can only be carried by
specific genera or species of mosquito. For example, only mosquitoes of the genus Aedes can carry the Zika virus. But let’s back up a little there are two
main types of mosquito-borne diseases in humans. Malaria is caused by a single-celled
protozoan. Most of the others are caused by viruses known as arthropod-borne
viruses or arboviruses for short. Arboviruses can infect both an arthropod – usually a mosquito or a tick – and a vertebrate – in this case, humans. Typically, viruses latch on to host cells by sticking to proteins on them called
receptors. If a cell doesn’t have the right
receptor, the virus can’t get in. And arboviruses recognize receptors on both insect and human cells. They can infect them both. So an arbovirus can jump
from mosquitoes to humans because it can use the receptors on insect cells to get
from the mosquito’s stomach to its salivary glands. From there, it can
replicate and infect the next human. By contrast, influenza viruses don’t have
this ability because they can’t recognize insect cell receptors. So it’s
unlikely that it, or any regular old virus, could get from a mosquito’s
stomach to a human. The malaria parasites’ process is even weirder. It can reproduce both sexually and
asexually, but it needs a human and two mosquitoes to do it. First, immature
parasites enter the human body through the salivary glands of the mosquito. They
mature in the liver and then hijack our red blood cells and divide. This is the
asexual part of their life cycle. But some of these parasites – instead of just
dividing – produce the precursors to sex cells, like the protozoan version of
sperm and eggs. Those then get sucked up by another
mosquito. Those proto-sex cells then mature and combine inside the second mosquito,
which is the sexual reproduction part, producing new parasites to infect the
next person. Which, I gotta say, is a pretty slick system, but that does not
change how I feel about those protozoans or the mosquitoes they rode in on. Thanks for watching and thanks especially to all of our patrons on Patreon who keep
these answers coming. If you would like to submit questions to
be answered, or get some videos a few days early, you can go to patreon.com/scishow and if you just want to keep getting smarter with us you can go to
youtube.com/scishow and subscribe. 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…

100 thoughts on “Why Can Mosquitoes Transmit Zika, But Not the Flu?

  1. QQ: why do we like different foods at different ages? for an example; Kids hate veggies but as they mature they start to like them.

  2. what about the structural differences in the receptor protein complexes that account for the stuff that you have explained. This felt like a pretty vague explanation to me. I want more details.

  3. There was a mosquito on my shoulder while watching this video. He saw the whole thing and got away. Sorry guys.

  4. We should genetically manufacture ebola and AIDS so it can be carried by mosquitoes and fix the Africa problem. Then we can just eradicate mosquitos completely once they clean up Africa for us.

  5. mafucker i realy do eat mosquitoes its the legacy of the dimetrodon only true apex predators eat mosquitoes humans don't eat mosquitoes because they are wimps and loosers🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲🐲

  6. I have a question, when I wake up in the middle of the night and watch a video how come the video seems faster than normal?

  7. malaria reminds me of an interesting question i came up when trolling as a creationist, how did complex life cycles evolved – like some parasites with 2 intermediary hosts and non parasitic life stages? theres very little research on this topic and existing theories are shaky at best, heres good starting point 10.1038/nature02012

  8. The process for Malaria transmittal just makes me marvel at the complexity of micro life

    fuck micro life

  9. While nothing in this video was false, the importance of cell receptors is misleading if you simply focus on the ability of the viruses to replicate in both mosquitoes and humans. The virus does not HAVE to be able to replicate in the mosquito to be able to be transmitted. The more relevant point about receptors is that influenza can only bind to and infect a specific subset of cells with a specific receptor in the lung epithelial cells. Mosquitoes aren't exactly likely to take a blood meal there. This is also why its 100% false that some people believe the flu vaccine gives them the flu. You can't get the flu from the flu vaccine, from a mosquito biting you after biting someone with the flu, or even from someone with the flu sneezing on your leg or arm. It has to go in through your respiratory tract and reach your lungs.

  10. Why is the Zika virus patented by a Foundation that worked on the GMO mosquito program with the Bill gates foundation? Also, why did the Zika outbreak happen in areas these GMO mosquitoes were released in?

  11. I threw a can of Campbell Soup through a food processor with some extra stuff like… roasted seaweed and a handful of cheezits. Have a severe case of mouth ulcers can't even eat the soft veggies in the soup as a result. It… didn't come out quite as planned and I needed to reprocess it but didn't have the energy. So I placed the soup (now in a bowl and some I had put in a large mug) in my fridge with the ladle I was going to use to portion it out as I ran it through the processor again in the bowl. Covered the bowl with tin foil because I was out of plastic wrap but didn't cover the mug, and left it for a day and a half when I went to get it out the bowl had frozen solid. The mug however stayed perfectly…sludgy and nothing else near that part of the fridge was remotely frozen. Was it because the tin foil was holding in all the heat from the soup and later the cold?

  12. Why does the parasite reproduce asexually to then reproduce sexually? Why not just continue reproducing asexually, to remove the factor of having to have another individual to reproduce with?

  13. What are those white lines in the sky by airplanes, why are they so visible but the airplanes are not?

  14. ZIKA VIRUS IS A MAN-MADE BIO-WEAPON PEOPLE.. THE GLOBAL ELITES AND GOVERNMENTS BROUGHT IN GMO MOSQUITOES TO INFECT THE AREAS THAT HAVE ZIKA.

  15. Next time you see a mosquito sucking some blood from you don't swat it, instead, pinch the skin around the mosquito. The mosquito can't detach and will blow up from sucking up too much blood

  16. "Are you like most humans" – immediately said no
    "Do you hate mosquitos?" – changed my answer to yes.

  17. Sure about that, i was laid up for 24 hours after getting assaulted by mosquitos. I figured I survived the west Nile virus. It was flu like.

  18. In the beginning (0:35) you say that arboviruses require both, mosquito and human as hosts. However, it has been shown that at least ZIKV can be transmitted sexually, i.e. from human to human without the mosquito vector (http://www.nejm.org/doi/full/10.1056/NEJMc1604449). In addition to the lack of suitable receptors in the mosquito, viruses that are take up with the blood "meal" will get digested and lose infectivity. The requirement of the mosquito as host would be much more applicable to parasites such as P. falciparum as part of its life cycle needs to be completed in the gut tract.
    For everyone who wants to know more about these fascinating topics I recommend the TWiX series by Prof. Racaniello et al. over at www.microbe.tv

  19. Hi everyone. i'm new to this channel. I wanna know if bowed legs are stronger then 'normal/linear' legs. I have bowed legs (normal bowed, not rickets bowed) and I'm intrigued to as to whether if I jump for example, if shock absorbed better in these legs than in that of another and if the legs are more likely or less likely to break under stress because of the bend… thanks

  20. Why dont they spread hiv? Blood to blood transfer, or if they bite a certain blood type, will they bite the same blood type or different blood type?

  21. Can we all stop with this zika fear mongering? Mosquitoes do not carry the zika virus. It was all started by Monsanto spraying chemicals in our foods.

  22. If a mosquito bites someone with HIV or AIDS, then bites a healthy person, will that person get what the last person had?

  23. "… but that does not change how I feel about those protozoans.. or the mosquitoes they rode in on." LOL!!!

  24. Thank you for this video for several reasons I'm not going to print here. Just keep up the good work!

  25. Mosqutos suuuuuuuuuuuuck
    Mosquitos suuuuuuuuUUUUUUuuuuuck
    They really really really really really really really really suck

  26. Question unrelated to this video that has been on my mind: Why does our skin turn 'black and blue' with severe injury and what function does it have to help the body?

  27. That's not really a full answer. After all, needles can't get infected with diseases (because they're not alive), but they can still transmit diseases. If a mosquito drinks human blood contaminated with influenza viruses, why can't the influenza hang around the proboscis or cling to surfaces in the mosquito's upper digestive tract? Even if the mosquito can't be infected itself, why can't it still be a physical vector for disease?

  28. is lie to say that mosquitos transmit diseases, they CanNOT, is not scientifically possible for mosquitos to transmit any disease nor any virus.
    besides Viruses are not natural for the environment of planet earth.

  29. Dear SciShow Team (Or whoever knows the answer),

    You said that some arboviruses reproduce sexually AND a sexually. Why is this? Is this to capitalize on both of the best features of each type of reproduction, such as the ease and independence of asexual reproduction as well as the better gene variation and higher mutation rates of sexual reproduction.
    I'd really like to know.

    Sincerely,
    Jack A Lepien, Esquire

  30. Why can mosquitoes transmit AIDS, but not the flu? No. I mean who was worried about them transmitting "the flu"? What was the REAL question, but certain people would NEVER even go there, because to even speak such a question makes one a HOMOPHOBE! Oh no! They're gonna call me a mean ol' name because I asked a sensible question!

  31. Question: Why don't humans have an option similar to tick medications for dogs that seemingly kill off the ticks that bite them/discourage them from biting? It seems to me that if there were such a medication/supplement for people that worked on ticks, mosquitoes, and other parasites, it could work wonders for decreasing those populations and thus the diseases they carry.Also, I bought an electrified racket for killing mosquitoes and it works wonders; highly recommended.

  32. Better question: why does the human immune system not have the ability to fight HIV, HSV-1 & 2, and other virus? One would think it would have the ability to "out smart" the viruses.

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