People have been scared of rabies for thousands of years,
几千年来人们一直害怕得狂犬病
many times depicting their fear
多次用恶狗的画作和雕塑
in drawings and carvings of menacing dogs.
来描述他们的恐惧
But rabies is scary for more reasons than just a painful bite.
但狂犬病之所以吓人 不仅仅是咬伤很疼
Because once the virus is inside us,
因为一旦感染狂犬病毒
it not only destroys our body, but damages our mind,
它不但摧毁身体 还毁害思想
and it can happen fast,
狂犬病毒发作迅速
or lay dormant for years before fatally attacking.
或在致命攻击前 能蛰伏数年
So how exactly do we get from a dog bite
那我们究竟是如何从被狗咬伤
to a complete behavioral change to death?
到行为完全改变 然后到死亡的呢?
The virus that causes rabies is spread through saliva,
狂犬病毒通过唾液传播
so the most common way to contract rabies
感染狂犬病的最常见途径
is through an animal bite,
是通过动物咬伤
most likely from a dog, bat, raccoon, skunk or fox.
很可能是狗 蝙蝠 浣熊 臭鼬或者狐狸的咬伤
There have been a few, rare cases of transmission through infected organ donors,
也有很少的案例是通过器官捐赠者感染
and even rarer instance of a lab accident,
甚至更罕见的由实验室事故导致的感染
but for the most part
但大多数的感染
it comes down to a bite from a rabid animal.
归结于狂犬病动物的咬伤
So even though it’s a virus that can infect and kill humans,
即使狂犬病毒能感染 杀死人类
it’s studied considerably in veterinary labs.
但仍是由兽医实验室进行研究
OK. I am Dr. Susan Moore.
大家好 我是Susan Moore医生
I’m the laboratory director of the rabies laboratory at Kansas State University,
堪萨斯州立大学 狂犬病实验室负责人
part of the veterinary diagnostic lab within the vet school here.
而部分的兽医诊断实验室 则位于兽医学院
We are the largest rabies serology laboratory in the world.
我们有世界上最大的 狂犬病血清学实验室
So the rabies virus is in the family lyssa virus,
狂犬病毒属于狂犬病毒属家族
lyssa means rage really.
它使感染人群变得易怒
So that kind of tells you what this group of viruses are capable of.
而这正是这批病毒的可怕之处
And what they’re capable of
同时狂犬病毒
is causing a very quick and painful death
通过进入大脑
caused by the virus making its way into your brain.
能使人快速 痛苦地死去
It’s a neurotropic virus.
狂犬病毒是嗜神经性病毒
So that means it’s preferentially going to infect neural tissue
这意味着它会先感染神经组织
or neural cells.
或神经细胞
So when it gets injected into the skin or the muscle,
当狂犬病毒注入皮肤或肌肉时
it’s not going to replicate all that well
它不会复制得特别好
but all it needs to do is replicate enough that
而它需要做的是复制足够多的病毒
it can get to that neuromuscular junction
然后到达神经肌肉的连接处
where that it can go from the muscle cells
再从此处 离开肌肉细胞
into the central nervous system.
进入中枢神经系统
Now, at this point
目前 此时此刻
you’d think your immune system would kick in,
你以为你的免疫系统会起作用
recognize this dangerous intruder and destroy it.
会识别危险入侵者并消灭它
But, your immune system doesn’t see it.
但你的免疫系统并没看到它
This is thought to be
这是你的想当然
because the virus replicates slowly in the muscle tissue,
因为病毒在肌肉组织中复制的很慢
slow enough not to cause any alarm.
慢到不会引起任何警报
This gives it a chance to reach the nervous system,
这给了它到达神经系统的机会
where it hitches a ride up to the brain
在这里它可以扩散到大脑
and slips through the blood brain barrier.
还能悄悄穿过血脑屏障
It’s behind this shield where the rabies virus can flourish
而在血脑屏障后面 狂犬病毒能大量繁殖
while still being able to hide from our immune system,
同时它还能躲避我们的免疫系统
because the blood brain barrier evolved to
因为血脑屏障的进化是为了
keep dangerous or harmful things out.
阻止危险或有害物进入
But sometimes that includes immune cells.
但有时血脑屏障会阻挡免疫细胞
In fact, if T cells do get past the blood brain barrier,
事实上 如果T细胞真通过了血脑屏障
the rabies virus has evasion techniques
狂犬病毒也有隐藏术
where it actually kills the T cells that are coming in.
它会杀死进入的T细胞 然后再藏在里面
As the virus replicates in the brain,
当病毒在大脑中复制时
it starts to mess with the brain’s cellular proteins,
它开始扰乱脑细胞蛋白质
causing neural dysfunction.
导致神经系统紊乱
This is where certain symptoms of rabies start
据此来判定 感染已完全开始
and how you can tell the infection has fully set in.
并且狂犬病某些症状 开始显现
Once the infection has fully set in,
一旦感染全面开始
it will start traveling back out through the nerves
狂犬病毒会通过神经
into innervated organs, hair follicles.
回到有神经支配的器官 毛囊
But again, particularly through to the salivary glands.
但同样 特别是会通过唾液腺
So that it could be transmitted out.
可以把病毒传播出去
These neurological symptoms also help the virus transfer to a new host.
这些神经症状也有助于病毒 转移到新宿主
Hypersalivation ensures there is enough rabies-infected saliva
病毒最佳的传输位置是嘴
in the optimal transmission location, your mouth.
所以唾液分泌过多会导致感染狂犬病
And hydrophobia, or trouble swallowing, ensures that it stays there.
恐水或吞咽困难 是让病毒能寄居在宿主
In animals, the aggression can result in an attack
动物的侵略性使其攻击
on another animal or a human.
别的动物或者人类
Put all three of those together
三个因素的共同作用
and you have a very effective way to ensure rabies is passed on.
会有效地确保狂犬病毒的传播
Saliva is the way that rabies is transmitted.
唾液是传播狂犬病的一种途径
The way the virus is adapted, it is not in blood.
适合病毒的生存环境 不是血液
It’s not in body fluids.
也不是体液
So it has to find a way to be transmitted effectively,
所以它必须找到一种有效的传播途径
right to perpetuate its existence.
来长久生存
Now, this neurological damage caused by the infection
目前 这种感染产生的神经损伤
is the thing that finally tips off the immune system.
是最终来提醒免疫系统的
However, this point it’s too late.
但到那时 就太迟了
Even though your immune system is finally going after the virus,
尽管免疫系统最终会攻击病毒
it has already spread throughout the body.
但它已经扩散到全身
After that you have to remember this period is pretty short.
之后 你要记得这个时期很短
There’s just a couple days
仅有几天而已
because then it’ll progress into a coma
因为随后会发展为昏迷
and then death which is usually due to some kind of organ failure.
然后是通常某种器官衰竭 导致的死亡
But a bite from a rabid animal
但被狂犬病动物咬一口
doesn’t always mean certain death.
并不意味着一定会死
People who have been exposed to the rabies virus
接触过狂犬病毒的人
can get a series of shots that can boost immune system
通过接种一些增强免疫力的疫苗
and fight off the virus,
来对抗病毒
you just need to get to it before it reaches the brain.
只需要阻止病毒到达大脑
So surviving rabies is all about
狂犬病毒的存活完全取决于
timing and the location where you get bit.
咬伤的时间和部位
Where you get bit, it plays a big role.
而伤口部位扮演着重要的角色
So since the virus has to travel through the nerve system,
既然病毒必须通过神经系统传播
the closer, and get to the brain,
那么伤口离大脑越近
the closer that bite is to the brain,
病毒就离大脑越近
the better for the virus.
从而对病毒越有益
Bats are a danger for that reason that
蝙蝠危险的原因在于
it’s going to be biting probably around your head or your hands.
它可能会咬你的头或者手
But also you don’t notice a bat bite
但你也没注意到蝙蝠的咬伤
because the teeth are so small and they are so small.
因为它们的牙齿太小 而它们本身也很小
Maybe you have a bat on your shoulder
或许 你的肩膀上有只蝙蝠
and you don’t know it.
但你并不知道
You just looked on your shoulder, didn’t you?
你刚才看了看自己肩膀 对吗？