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Leprosy brings to mind images of biblical beggars, lonely leper colonies,
麻风这种病会让我们想起圣经中的乞丐，麻风病收容所，
and seems, for some, to have all but disappeared into the history books.
对一些人来说，这种病似乎已经完全消失在历史书里了。
But leprosy stills haunts many parts of the world
然而，事实上，麻风病现在仍困扰着许多地方，
and there’s an absurd amount that we don’t know about the disease.
而且，我们对这种病所知甚少。
Leprosy has been around since at least 2000 B.C.
麻风病的历史至少可以追溯到公元前2000年，
but, after all this time, we still don’t really know how the disease is transmitted.
但时至今日，我们仍然不知道这种疾病是如何传播的。
We don’t know where it starts in the body.
也不知道它在人体内是如何发展起来的。
Oh, and we can’t grow leprosy bacteria in a culture.
噢，我们也无法在培养皿中培养麻风病细菌。
But... maybe we should start with what we do know.
那…或许我们应该从我们已经知道的地方下手。
My name is Cressida Madigan.
我叫克雷西达·麦迪甘。
I'm an assistant professor at UC San Diego in the molecular biology section.
是加州大学圣地亚哥分校分子生物学专业的助理教授。
And I work on leprosy and other neurological infections
我研究的是麻风病及其他神经性感染疾病，
to try to understand how these infectious agents are damaging our nervous system during infection.
了解这些感染因子是如何在感染过程中破坏我们的神经系统的。
I love micro-bacteria which is the kind of bacteria that causes leprosy.
我很喜欢研究微细菌，这是一种会引起麻风病的细菌。
They're very unusual organisms.
这种微生物非常不同寻常。
And part of what makes leprosy bacteria, or mycobacterium leprae, so unusual
麻风病细菌或麻风分枝杆菌之所以这么不同寻常，部分原因在于
is that it is thought to only be able to replicate inside a living cell.
这种细菌被认为只能在活细胞内复制。
These bacteria can't be grown in the lab the way that we grow other bacteria.
所以我们无法像培养其他细菌一样在实验室里培养这种细菌。
We don't know why.
至于为什么不能，我们也不清楚。
We don't know if maybe we're just missing a key component of the recipe that it needs to grow.
不知道是因为缺少了这种细菌繁殖所需配方的某个关键成分。
Could also be that leprosy simply can not grow outside of an animal.
还是因为麻风病细菌根本就无法在动物体外生长。
So, scientists like Dr. Madigan study leprosy inside living animals like mice, armadillos, and zebrafish.
所以，麦迪甘博士等科学家都是在活体动物，比如老鼠、犰狳和斑马鱼身上研究这种细菌。
But this still makes the bacteria difficult to observe and run tests on,
然而，即便如此，观察和测试这种细菌依然十分困难，
especially since it occupies a unique part of the body - the nerves.
主要原因是它控制的是非常独特的身体部分——神经。
It’s the bacteria invading the nerves and the immune system’s response
最终引起这种疾病的主要症状的
that eventually causes the major symptoms of the disease.
就是细菌对神经的入侵以及免疫系统对此作出的反应。
So, while we aren’t really sure how the disease gets into the body or how it travels to the nerve cells,
虽然我们不确定这种疾病是如何进入人体以及它如何传播到神经细胞的，
we know it infects what are called Schwann cells,
但我们知道它会感染所谓的“雪旺细胞”，
which produce the protective myelin sheath that covers neuronal axons,
而雪旺细胞能够产生保护神经轴突的髓鞘，
helping to conduct electrical impulses along the nerves.
帮助神经传导脉冲。
So there's some evidence that when leprosy infects Schwann cells,
有证据表明麻风细菌感染雪旺细胞后，
it stops those cells from being able to make myelin which is this sort of insulating wrapping that surrounds the axons of our nerves.
会阻止这些细胞产生髓鞘，而髓鞘相当于包裹神经轴突的一种绝缘体。
Something about the infection causes the protective myelin to die.
感染会导致保护性髓鞘的死亡。
And this is because the bacteria is destroying the small, but mighty mitochondria in the nerve cells.
因为细菌破坏了神经细胞中但个头不大但作用很大的线粒体。
So mitochondria are sort of like the batteries within cells.
线粒体则有点像细胞内的电池。
They produce the energy for the cell so that it can function.
它们为细胞提供维持功能所需的能量。
So, as a cell, if you don't have mitochondria, you will essentially die at some point, right?
所以，作为一个细胞，如果你没有线粒体，你就会在某个时刻死去，对吧？
Over time, the nerve axons also become damaged by the immune system’s response to the bacteria,
随着时间的推移，免疫系统对细菌的反应也会损伤神经轴突，
which is why people with leprosy can lose feeling in their skin.
麻风病患者皮肤会失去知觉就是这个原因。
But the immune system isn’t activated immediately
但是免疫系统并不会立即被激活，
and that’s because leprosy bacteria is notorious for moving at a snail’s pace.
因为麻风病菌转移的速度出了名的慢。
While other bacteria like e. Coli can replicate in as short of a time as 20 minutes and disseminate quickly,
大肠杆菌等细菌20分钟就能完成复制然后迅速扩散，
leprosy bacteria replicates only once every two weeks or so.
麻风病细菌大约每两周才能完成一次复制。
So someone could be infected for years and not experience any symptoms because the bacteria isn’t setting off any alarms.
所以，有些人可能感染麻风病病菌已经很多年都没有表现出任何症状，因为细菌没有触发到任何免疫系统的警报。
This also makes the bacteria difficult to treat.
这种病也因此变得非常难治。
Many antibiotics work by targeting bacteria that are replicating.
许多抗生素都只能作用于正在复制的细菌。
So if you're a bacterium and you're not replicating,
所以，如果你是一个细菌，但你没有进行复制，
then you will be naturally resistant to several classes of antibiotics.
那好几种类型的抗生素都将奈何不了你。
To treat the disease, you’d have to take a cocktail of various antibiotics daily for up to two years
要治疗这种疾病，你必须每天服用含有多种抗生素的药物并且坚持服用两年，
to make sure the drugs hit the bacteria at the exact moment it’s trying to replicate.
才能确保药物在细菌试图复制的精确时刻命中细菌。
And you would need to take multiple antibiotics at one time
你还需要同时服用多种抗生素
to ensure that the bacteria doesn’t become resistant to the treatment.
确保细菌不会产生抗药性。
Which is not ideal.
这也不是理想的办法。
But the good news is, leprosy really isn’t that contagious compared to other diseases.
但好消息是，与其他疾病相比，麻风病的传染性并不强。
Part of the stigma of leprosy is that this disease is very contagious.
麻风病的污名之一就是这种疾病具有很强的传染性。
But that's actually not true.
然而，事实并非如此。
In fact, you need to be around someone with leprosy for a long time to catch the disease.
事实上，你需要和麻风病患者共处很长时间才能感染这种疾病。
It also helps that 95% of people are naturally immune to leprosy.
而且，95%的人天生就对麻风病免疫。
So in order to contract leprosy you have to be living with a family member
所以，你必须和已经被感染，已经得了这种病的家人生活在一起，
who has the disease, who is infectious and you have to have close intimate contact with that person for a period of years.
和他亲密接触好几年才能感染成功。
And while the symptoms are undesirable, leprosy doesn’t directly cause death.
虽然麻风病的症状比较辣眼睛，但还不至于要命。
In some patients, the symptoms take decades to manifest.
有些病人的症状几十年才显现出来。
So… like we said earlier about the leprosy bacteria.
所以，就像我们之前形容麻风病细菌时说过的那样。
They're very unusual organisms.
它们是非常不同寻常的微生物。
The Byzantines knew about leprosy.
拜占庭人对这种病就已经有所了解。
They knew that it was infectious.
他们知道这种病会传染。
And so to try to stop the spread of leprosy throughout the Byzantine Empire,
所以，为了阻止这种病在拜占庭帝国的传播，
the Byzantines would assign leprosy patients to leprosaria
拜占庭人把麻风病患者都安置到了麻风病院，
which were like very posh leper colonies essentially
差不多都是非常豪华的麻风病收容所，
and the leprosarias were actually really nice places for patients to live.
那些医院条件非常好。
They got free medical care, free food, housing and
有免费医疗，免费食宿等，
so life was so good within the leprosaria that people started trying to fake the symptoms of leprosy in order to be admitted.
也因为那些医院生活实在太安逸了，有些人便假装出现了麻风病的症状，企图借机混进去。
Oh, to be a leper in the Byzantine Era, am I right?
拜占庭时代的麻风病人也太幸运了吧，你们说是吧？
