中級 美國腔 172 分類 收藏
開始影片後,點擊或框選字幕可以立即查詢單字
字庫載入中…
回報字幕錯誤
Only one human disease in history has been fully stamped out; smallpox, with the World
Health Organization declaring it eradicated way back in 1980.
But, we might be close to eradicating a second disease; polio.
Yes, the disease that brings up imagery of wheelchairs and iron lungs may soon be on
its way out, but as of 2019, we're not there yet.
Polio, also known as poliomyelitis, is an infectious disease caused by the aptly-named
poliovirus, which comes in three strains, and is spread mostly by consuming contaminated water.
And by contaminated we mean, well…
So, the kid poops it out, the virus gets in the water around there, usually in the sewage.
And then, sometime in the next day or two or three or a week or something, some other
kid will drink the sewage and it'll get in that kid and they'll cycle around like that.
Hi, I'm Jay Wenger, I'm the Director of Polio at the Bill & Melinda Gates Foundation.
I started working on polio eradication in 2002, when I went to India, and I joined the
Gates Foundation in 2011, and have been there ever since.
Polio can be passed through the air with oral fluids, like from a cough or a sneeze, but
the cycle today usually begins with fecal oral transmission, mostly in areas with poor sanitation.
Once swallowed the virus heads straight to your intestines, finding places to replicate along the way.
Now, most of the time your body will take care of the invader with an immune response,
giving you flu-like symptoms or no symptoms at all.
There are two things that happen with a natural infection.
Well, there are lots of things that happen, but the two main ones are, you develop humoral antibodies.
And those are antibodies that float around your bloodstream.
And basically will, if the virus gets into your bloodstream, they'll attack it and you'll end up ejecting it.
The second way is producing mucosal antibodies that are secreted in the gut to ensure it doesn't reproduce.
But if those antibodies in the blood don't stop the infection, it could result in paralysis,
which occurs in about one out of every 200 people who contract the poliovirus.
That's because if the virus survives into your bloodstream, they can find a way into
your nervous system and eventually get into the anterior horn cells of your spinal cord.
Basically, they reproduce then they go into the cell and they reproduce
there, and they result in death of the actual anterior horn cell, and
is that cell that the message from the brain transmits to the muscle.
And it causes an irreversible cell death.
So, if these anterior horn cells die, it disrupts the transmission between the brain and the muscles,
such as the muscles in the torso, limbs, and between our ribs.
And which part of the body becomes paralyzed will depend on which cells die.
But, for instance, if it attacks the nerves that ultimately go to the leg, say, the right
leg, it can kill those nerves, and then, messages from the brain to the leg don't get there anymore.
And so, the leg will be paralyzed, you won't be able to move it.
That usually happens pretty quickly, usually within a day.
But, if the virus gets to the nerves that influence your breathing muscles, that's especially
bad, because you then can't breathe and your lungs don't work.
Weakened lungs could result in death, or in some cases, bringing in a machine to help
the patient breathe, like the iron lung
All of these effects of polio; weakened lungs, paralysis and death, are why so many people
are still focused on eradicating the disease.
Polio was a huge deal in the United States. It was actually the most feared infectious
disease of like the 40s and 50s in the United States.
So, there was a huge push to develop a polio vaccine.
And the first polio vaccine that got developed was developed by Salk, and that was based
on a killed poliovirus preparation.
And so, that one was great, it was a breakthrough of its time.
And if you inject killed poliovirus, what you get are the humoral antibodies.
This boost of humoral antibodies in the blood helps lower the chance that the virus will
get to your spine, reducing the risk of polio-induced paralysis.
And so, the vaccine is good in that it prevents paralysis, and it has a little bit of an impact on the amount that you excrete.
It reduces it a little bit, but not a lot.
So that, especially in tropical countries with rotten sanitation, the IPV is not actually
a good tool to get rid of the virus from a population.
That's because the IPV isn't as effective at boosting the mucosal antibodies, so the
virus still reproduces in the gut, ensuring large numbers are still passed on through poop into water supplies.
But a couple years later, Sabin came out with an oral vaccine.
This Sabin vaccine was developed using live, weakened strains of poliovirus and helped
not only trigger humoral antibodies to protect from paralysis, but also mucosal antibodies,
which greatly reduces the amount of poliovirus passed on through poop.
So, it was a huge difference and people found that soon that after using that in populations,
giving every kid in the population the OPV, a couple times, you would actually drive the wild virus away.
This happened in Latin America and wild poliovirus was eventually eliminated from the
entire Americas, and then in Europe and Eastern Asia which essentially became wild poliovirus free.
But things sort of got slowed down a little bit in the 2000s, when we got down to like four countries.
And that was India, Pakistan, Afghanistan and Nigeria.
And we think that we are making progress toward finishing off polio in these last places.
India had their last case in 2011, we're hoping Nigeria had their last case in 2016.
And we're down to only two countries right now, Afghanistan and Pakistan.
If we get rid of the wild poliovirus there, it won't be anywhere else, there's nowhere else to be.
And so that will basically stop that as a cause of paralysis for kids everywhere.
提示:點選文章或是影片下面的字幕單字,可以直接快速翻譯喔!

載入中…

我們幾乎根除了小兒麻痺,但怎麼做到的? (How Have We Almost Eradicated Polio?)

172 分類 收藏
Jerry Liu 發佈於 2019 年 9 月 8 日    Jerry Liu 翻譯    Evangeline 審核
看更多推薦影片
  1. 1. 單字查詢

    在字幕上選取單字即可即時查詢單字喔!

  2. 2. 單句重複播放

    可重複聽取一句單句,加強聽力!

  3. 3. 使用快速鍵

    使用影片快速鍵,讓學習更有效率!

  4. 4. 關閉語言字幕

    進階版練習可關閉字幕純聽英文哦!

  5. 5. 內嵌播放器

    可以將英文字幕學習播放器內嵌到部落格等地方喔

  6. 6. 展開播放器

    可隱藏右方全文及字典欄位,觀看影片更舒適!

  1. 英文聽力測驗

    挑戰字幕英文聽力測驗!

  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔