TED2007
Paul Ewald: Can we domesticate germs?
保罗.埃瓦尔德问，我们能驯化病菌么？
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进化生物学家保罗.埃瓦尔德把我们带入下水道来讨论病菌。为什么病菌种的多数是有害的？我们如何才能把有害的病菌变为无害的？为了寻找答案，他考察了一个令人作呕而又有吸引力的实例：痢疾。
Paul Ewald - Evolutionary biologist
After years of studying illness from the germs' point of view, microbiologist Paul Ewald believes that Big Pharma is wrong about some very big issues. What's right? The leader in evolutionary medicine posits radical new approaches. Full bio
After years of studying illness from the germs' point of view, microbiologist Paul Ewald believes that Big Pharma is wrong about some very big issues. What's right? The leader in evolutionary medicine posits radical new approaches. Full bio
Double-click the English transcript below to play the video.
00:18
What I'd like to do is just drag us all down into the gutter,
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我想做的仅仅是将大家拽下排水沟，
00:21
and actually all the way down into the sewer
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并且实际上，一路下到下水道里
00:23
because I want to talk about diarrhea.
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因为我想谈谈痢疾。
00:25
And in particular, I want to talk about
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而且特别是，我想谈谈
00:29
the design of diarrhea.
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痢疾的设计。
00:31
And when evolutionary biologists talk about design,
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当进化生物学家谈起设计的时候
00:33
they really mean design by natural selection.
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他们实际上表示的自然选择的设计。
00:37
And that brings me to the title of the talk,
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这就引出了我这次演讲的题目，
00:39
"Using Evolution to Design Disease Organisms Intelligently."
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“通过进化来巧妙地设计病菌”。
00:43
And I also have a little bit of a sort of smartass subtitle to this.
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并且我也有一个稍显聪明一些的副标题。
00:47
But I'm not just doing this to be cute.
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但我这么说不是为了引人注目。
00:49
I really think that this subtitle explains
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我确实认为这个副标题说明了
00:52
what somebody like me, who's sort of a Darwin wannabe,
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像我这样的达尔文的崇拜者，
00:55
how they actually look at one's role in
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他们事实上是如何看待一个人在
00:58
sort of coming into this field of health sciences and medicine.
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健康科学和医学领域中的角色。
01:02
It's really not a very friendly field for evolutionary biologists.
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对进化生物学家们来说这真不是个友好的领域。
01:05
You actually see a great potential,
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你确实看到了巨大的潜力，
01:07
but you see a lot of people who are sort of defending their turf,
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但你也会看到许多人固步自封，
01:10
and may actually be very resistant, when one tries
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实际上这些人在他人试图
01:14
to introduce ideas.
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提出新观点时也许会非常的抗拒。
01:16
So, all of the talk today is going to deal with two general questions.
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因此，今天所有的讨论都是为了解决两个普通的问题。
01:21
One is that, why are some disease organisms more harmful?
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一个是，为什么一些病菌更有害，
01:24
And a very closely related question, which is,
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而一个与之关系非常密切的问题是，
01:26
how can we take control of this situation once we understand
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一旦我们有了第一个问题的答案，
01:30
the answer to the first question?
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我们如何才能控制这种情况？
01:31
How can we make the harmful organisms more mild?
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我们如何才能使这些有害病菌的危害变得更轻微些？
01:34
And I'm going to be talking, to begin with, as I said,
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而我将要谈论的，正如我所说，首先从
01:36
about diarrheal disease organisms.
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痢疾病菌开始。
01:38
And the focus when I'm talking about the diarrheal organisms,
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并且，当我谈论痢疾病菌时，
01:41
as well as the focus when I'm talking about any organisms
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同样，当我谈论任何
01:44
that cause acute infectious disease,
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导致急性传染病的病菌时，
01:46
is to think about the problem from a germ's point of view,
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重点是从细菌的角度来思考这类问题。
01:49
germ's-eye view.
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细菌的视角。
01:51
And in particular, to think about a fundamental idea
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尤其是考虑一个基本的观点，
01:55
which I think makes sense out of a tremendous amount of variation
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我认为在有害的病菌中出现
01:58
in the harmfulness of disease organisms.
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大量的变异是合理的。
02:01
And that idea is that from the germ's-eye point of view,
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这一观点是从细菌的角度来看的，
02:05
disease organisms have to get from one host to another,
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病菌不得不从一个宿主迁移到另一个宿主，
02:08
and often they have to rely on the well-being of the host
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并且它们通常不得不依赖于健康的宿主
02:12
to move them to another host.
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把它们迁移到另一个宿主上。
02:14
But not always.
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但并不总是这样。
02:16
Sometimes, you get disease organisms
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有时你染上的病菌
02:18
that don't rely on host mobility at all for transmission.
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根本不依赖于宿主的移动性来传播。
02:20
And when you have that, then evolutionary theory tells us
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而当你染上他们后，进化论告诉我们
02:23
that natural selection will favor the more exploitative,
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自然选择会倾向于更会取巧的，
02:27
more predator-like organisms.
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更有侵略性的细菌。
02:29
So, natural selection will favor organisms
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所以，自然选择会倾向于
02:31
that are more likely to cause damage.
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更能造成破坏的细菌。
02:33
If instead transmission to another host requires host mobility,
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如果传播至另一宿主依靠原宿主的移动性，
02:37
then we expect that the winners of the competition
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那么我们可以预料竞争的胜利者
02:40
will be the milder organisms.
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将是那些温和的细菌。
02:42
So, if the pathogen doesn't need the host to be healthy and active,
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不过，如果病菌不需要宿主保持健康和活力
02:45
and actual selection favors pathogens
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而且实际上自然选择倾向于选择
02:48
that take advantage of those hosts,
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从宿主获利的细菌，
02:50
the winners in the competition are those that exploit the hosts
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竞争的胜利者就是那些为了繁殖成功
02:52
for their own reproductive success.
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而剥削宿主的病菌。
02:54
But if the host needs to be mobile in order to transmit the pathogen,
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但是，如果需要宿主移动来传播病菌，
02:59
then it's the benign ones that tend to be the winners.
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那么那些温和的病菌往往会成为胜利者。
03:01
So, I'm going to begin by applying this idea to diarrheal diseases.
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所以，我将从把这些观点应用于痢疾病菌作为（我的演讲的）开始。
03:05
Diarrheal disease organisms get transmitted in basically three ways.
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痢疾病菌有三种基本的传播途径。
03:08
They can be transmitted from person-to-person contact,
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它们能够通过人与人间的接触传播，
03:11
person-to-food-then-to-person contact,
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当某人吃了被污染的食物时，
03:13
when somebody eats contaminated food,
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会发生从人到食物再到人的传播。
03:15
or they can be transmitted through the water.
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或者它们能通过水进行传播。
03:17
And when they're transmitted through the water,
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当他们通过水传播时，
03:19
unlike the first two modes of transmission,
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不像前两种传播方式，
03:21
these pathogens don't rely on a healthy host for transmission.
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这些病菌并不依赖于健康的宿主进行传播。
03:25
A person can be sick in bed and still infect tens, even hundreds
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一个卧病在床的人仍能传染数以十计，甚至数以百计的
03:27
of other individuals.
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其他人。
03:29
To sort of illustrate that, this diagram emphasizes that
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为了说明这些，这个图表表明，
03:32
if you've got a sick person in bed,
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如果有一个卧床的病人，
03:34
somebody's going to be taking out the contaminated materials.
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总得有人来处理那些被污染的物品。
03:37
They're going to wash those contaminated materials,
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他们将清洗这些被污染的物品，
03:38
and then the water may move into sources of drinking water.
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然后用于清洗的水可能会流至饮用的水源。
03:42
People will come in to those places where you've got
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人们将到这些水源处取用
03:45
contaminated drinking water,
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这些被污染的饮用水，
03:46
bring things back to the family,
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带着他们回到家中，
03:47
may drink right at that point.
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他们也许在那儿就会喝一些水。
03:48
The whole point is that a person who can't move
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重点是，一个不能移动的人
03:51
can still infect many other individuals.
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仍会传染其他许多人。
03:53
And so, the theory tells us that
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因此，这理论告诉我们
03:56
when diarrheal disease organisms are transported by water,
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当痢疾病菌通过水进行传播时，
04:01
we expect them to be more predator-like, more harmful.
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我们认为它们会变得更有侵略性，更加有害。
04:03
And you can test these ideas.
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你可以测试一下这些观点。
04:05
So, one way you can test is just look at all diarrheal bacteria,
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测试它的一个方法就是，仅仅等着看这些痢疾病菌
04:07
and see whether or not the ones that tend to be
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看看它们是不是更倾向于
04:09
more transmitted by water, tend to be more harmful.
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通过水进行传播，更加的有害。
04:11
And the answer is -- yep, they are.
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答案是 —— 是的，的确是的。
04:13
Now I put those names in there just for the bacteria buffs,
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现在我把这些名字放在这儿，仅仅为了细菌迷们，
04:16
but the main point here is that --
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但是要点是--
04:19
(Laughter)
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（笑声）
04:20
there's a lot of them here, I can tell --
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这儿有许多（细菌迷），我得说--
04:21
the main point here is that those data points
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要点是，这些数据点
04:25
all show a very strong, positive association between
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显示了在两件事之间有很强的正向联系：
04:27
the degree to which a disease organism is transmitted by water,
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那就是这些病菌对水传播的依赖性，
04:31
and how harmful they are,
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和它们（对人）的危害，
04:32
how much death they cause per untreated infection.
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也就是在未治疗的情况下感染它们导致死亡的人数。
04:35
So this suggests we're on the right track.
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因此这表明我们的思路是正确的。
04:37
But this, to me, suggests that we really need
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但是，对我而言，这表明我们的确需要
04:42
to ask some additional questions.
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问一些附加的问题。
04:43
Remember the second question that I raised at the outset was,
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回想一下我在开始提出的问题中的第二个问题，
04:46
how can we use this knowledge
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我们怎样才能利用这些知识
04:48
to make disease organisms evolve to be mild?
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来使得病菌进化的更加温和？
04:51
Now, this suggests that if you could just block waterborne transmission,
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现在这表明，如果你能阻止水媒传播,
04:53
you could cause disease organisms to shift from
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那么就能使病菌从
04:56
the right-hand side of that graph to the left-hand side of the graph.
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从这图表的右边转移到左边。
04:59
But it doesn't tell you how long.
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但是图中并没有表明这需要多久。
05:01
I mean, if this would require thousands of years,
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我是说，如果这需要数千年的话，
05:03
then it's worthless in terms of controlling of these pathogens.
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就控制这些病菌而言就没有意义了。
05:05
But if it could occur in just a few years,
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但如果这能在仅仅几年中就奏效
05:07
then it might be a very important way to control
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那么它也许就是一个非常重要的控制途径，
05:11
some of the nasty problems that we haven't been able to control.
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来控制那些我们没有控制住的严重的问题。
05:14
In other words, this suggests that we could
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换句话说，这表明我们能够
05:16
domesticate these organisms.
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驯化这些病菌。
05:18
We could make them evolve to be not so harmful to us.
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我们能让它们进化的对我们不是那么有害。
05:21
And so, as I was thinking about this, I focused on this organism,
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而且，如我所回想起的我所关注的一种病菌，
05:24
which is the El Tor biotype of the organism called Vibrio cholerae.
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一种被称为霍乱弧菌的埃尔托生物型细菌。
05:28
And that is the species of organism that is responsible
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这种类型的细菌
05:32
for causing cholera.
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导致了霍乱。
05:34
And the reason I thought this is a really great organism to look at
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而我认为这种病菌是个好例子的原因，
05:36
is that we understand why it's so harmful.
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是因为我们理解了为什么它如此有害。
05:39
It's harmful because it produces a toxin,
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它有害的原因是它产生一种毒素，
05:42
and that toxin is released when the organism
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并且，当这些病菌在肠道中时
05:44
gets into our intestinal tract.
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会释放这些毒素。
05:45
It causes fluid to flow from the cells that line our intestine
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这导致了体液从肠细胞流至
05:49
into the lumen, the internal chamber of our intestine,
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肠腔内--肠内部的空间，
05:52
and then that fluid goes the only way it can, which is out the other end.
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然后这些液体去了他们唯一能去的地方，排出体外。
05:55
And it flushes out thousands of different other competitors
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这一过程冲走了数以千计的那些可能会使弧菌生存困难的
05:58
that would otherwise make life difficult for the Vibrios.
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各种其他竞争者。
06:01
So what happens, if you've got an organism,
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所以，如果你感染了一个病菌，会发生什么
06:03
it produces a lot of toxin.
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它会产生许多毒素。
06:04
After a few days of infection you end up having --
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感染后的几天的最终结果--
06:07
the fecal material really isn't so disgusting as we might imagine.
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排泄物实际上并不像我们想象的那么恶心。
06:09
It's sort of cloudy water.
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它是一种浑浊的液体。
06:11
And if you took a drop of that water,
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如果你去一滴这样的液体
06:13
you might find a million diarrheal organisms.
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你也许能找到一百万只痢疾病菌。
06:16
If the organism produced a lot of toxin,
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如果病菌产生了很多毒素，
06:18
you might find 10 million, or 100 million.
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你也许会找到一千万或是一亿只。
06:20
If it didn't produce a lot of this toxin,
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如果它们没有产生很多毒素
06:22
then you might find a smaller number.
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那么你也许会找到较少数量的病菌。
06:24
So the task is to try to figure out
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所以，我们的任务是试着发现
06:28
how to determine whether or not you could get an organism like this
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如何来确定我们是否能通过阻止水媒传播
06:32
to evolve towards mildness by blocking waterborne transmission,
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使得这样的病菌朝着更温和的方向进化。
06:35
thereby allowing the organism only to be transmitted
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也就是只允许病菌通过
06:37
by person-to-person contact,
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人与人之间的接触传播，
06:40
or person-food-person contact --
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或者人-食物-人的接触传播。
06:41
both of which would really require that people be
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这两种方式实际上都需要人们
06:43
mobile and fairly healthy for transmission.
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能移动和有适当的健康来进行传播。
06:45
Now, I can think of some possible experiments.
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现在，我可以考虑一些可能的实验。
06:48
One would be to take a lot of different strains of this organism --
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一个实验需要许多不同株这类病菌--
06:51
some that produce a lot of toxins, some that produce a little --
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一些会产生许多毒素，一些产生很少毒素--
06:53
and take those strains and spew them out in different countries.
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然后把这些株放至不同的国家。
06:58
Some countries that might have clean water supplies,
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一些国家有清洁的水源供应，
07:01
so that you can't get waterborne transmission:
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因此不能进行水媒传播，
07:02
you expect the organism to evolve to mildness there.
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在那儿，病菌可能会进化的更加温和。
07:05
Other countries, in which you've got a lot of waterborne transmission,
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在另一些国家会有很多水媒传播，
07:08
there you expect these organisms to evolve
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这些病菌会朝着
07:10
towards a high level of harmfulness, right?
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更有害的方向进化，对么？
07:14
There's a little ethical problem in this experiment.
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这个实验会有些道德问题。
07:16
I was hoping to hear a few gasps at least.
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我（原本）以为至少会听到一些人抽冷气。
07:19
That makes me worry a little bit.
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（你们这么容易就接受了这个实验计划，）这倒让我有点担心。
07:21
(Laughter)
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（笑声）
07:22
But anyhow, the laughter makes me feel a little bit better.
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但无论如何，笑声让我感觉更好了点。
07:25
And this ethical problem's a big problem.
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但是这个道德问题是个大问题。
07:28
Just to emphasize this, this is what we're really talking about.
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只是为了强调，这是我们所谓的（道德问题）。
07:31
Here's a girl who's almost dead.
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这是个差点死去的女孩。
07:33
She got rehydration therapy, she perked up,
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她进行了补水治疗，她重新活泼起来，
07:35
within a few days she was looking like a completely different person.
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在几天内她看起来像完全另外一个人。
07:38
So, we don't want to run an experiment like that.
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所以我们并不想进行这样的一个实验。
07:40
But interestingly, just that thing happened in 1991.
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但是有趣地是，这些事在1991年发生了。
07:44
In 1991, this cholera organism got into Lima, Peru,
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1991年，在秘鲁的利马爆发了霍乱，
07:48
and within two months it had spread to the neighboring areas.
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在两个月内病毒就传播至邻国。
07:51
Now, I don't know how that happened,
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我现在都不知道这是如何发生的，
07:54
and I didn't have anything to do with it, I promise you.
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而且我也与此无关，我保证。
07:58
I don't think anybody knows,
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我不认为有人知道（这是怎么发生的），
08:00
but I'm not averse to, once that's happened,
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但是我并不反对，一旦一切已经发生，
08:03
to see whether or not the prediction that we would make,
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看看我们做的预测，
08:05
that I did make before, actually holds up.
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我之前做的预测，是不是对的。
08:08
Did the organism evolve to mildness in a place like Chile,
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病菌会在像智利那样
08:11
which has some of the most well protected water supplies
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有拉美保护得最好的水源供应的地方
08:14
in Latin America?
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进化的更温和么？
08:15
And did it evolve to be more harmful in a place like Ecuador,
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它会在那些水源保护的最差的地方，比如厄瓜多尔，
08:19
which has some of the least well protected?
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进化的更有害么？
08:21
And Peru's got something sort of in between.
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而秘鲁的水源供应保护在这两种情况之间，处于中等保护程度。
08:23
And so, with funding from the Bosack-Kruger Foundation,
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因此，由波扎克-克鲁格基金会提供资金支持，
08:27
I got a lot of strains from these different countries
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我从不同国家得到了许多菌株
08:30
and we measured their toxin production in the lab.
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并且，我们在实验室中仔细测量了毒素的生产。
08:33
And we found that in Chile -- within two months of the invasion of Peru
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我们发现在智利--在病毒入侵秘鲁后的两个月内
08:37
you had strains entering Chile --
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就会在智利发现菌株。
08:39
and when you look at those strains,
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当留心观察这些菌株，
08:41
in the very far left-hand side of this graph,
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在这幅图的很靠左侧的地方，
08:43
you see a lot of variation in the toxin production.
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你会看到毒素生产中的许多变异。
08:46
Each dot corresponds to an islet from a different person --
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每个点对应着来自不同人的一个样本。
08:49
a lot of variation on which natural selection can act.
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自然选择会导致许多的变异。
08:51
But the interesting point is, if you look over the 1990s,
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但是有趣的地方时，如果你仔细看看90年代，
08:54
within a few years the organisms evolved to be more mild.
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仅仅几年病菌就进化的更温和。
08:58
They evolved to produce less toxin.
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它们进化的会产生更少毒素。
09:00
And to just give you a sense of how important this might be,
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为了让你们对这有多重要有个感觉，
09:02
if we look in 1995, we find that there's only one case of cholera,
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注意一下1995年起，在智利平均每两年
09:07
on average, reported from Chile every two years.
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我们只发现一例霍乱。
09:09
So, it's controlled.
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这说明它被控制住了。
09:11
That's how much we have in America,
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这就是我们在美洲所了解到的。
09:13
cholera that's acquired endemically,
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霍乱是地方性的。
09:15
and we don't think we've got a problem here.
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而我们不认为这儿有问题。
09:17
They didn't -- they solved the problem in Chile.
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没有--在智利他们解决了这个问题。
09:19
But, before we get too confident, we'd better look at some of those other countries,
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但在我们变得过于自信之前，我们最好看看其他一些国家的情况。
09:22
and make sure that this organism doesn't just always evolve toward mildness.
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并确认这一病菌并不总是朝着更温和的方向进化。
09:25
Well, in Peru it didn't.
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好吧，在秘鲁它不是的。
09:27
And in Ecuador -- remember, this is the place where it has
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而且在厄瓜多尔--别忘了这是
09:30
the highest potential waterborne transmission --
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最可能通过水媒进行传播的地方--
09:32
it looked like it got more harmful.
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看起来，它变得更加有害了。
09:33
In every case there's a lot of variation,
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在每个病例中都有许多的变异，
09:35
but something about the environment the people are living in,
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但这与那儿的人们所居住的环境有关，
09:38
and I think the only realistic explanation is that it's
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而且我认为水媒传播程度
09:41
the degree of waterborne transmission,
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是唯一正确的解释。
09:43
favored the harmful strains in one place, and mild strains in another.
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在一个地方对有害的菌株有利，而另一个地方则对温和的菌株有利。
09:47
So, this is very encouraging,
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这非常让人振奋，
09:49
it suggests that something that we might want to do anyhow,
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这个结果表明我们应该，其实无论如何我们都应该，
09:51
if we had enough money, could actually give us a much bigger bang for the buck.
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如果我们有足够的资金，我们可以取得更大的进展，
09:54
It would make these organisms evolve to mildness,
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我们可以使得这些病菌进化的更温和，
09:56
so that even though people might be getting infected,
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以便人们即使感染了病毒，
09:58
they'd be infected with mild strains.
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他们也是被温和的菌株所感染。
10:00
It wouldn't be causing severe disease.
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这不会导致严重的疾病。
10:02
But there's another really interesting aspect of this,
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但这有另一个真实而有趣的方面，
10:04
and this is that if you could control the evolution of virulence,
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就是说如果你能控制致病力的进化，
10:07
evolution of harmfulness,
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危害性的进化，
10:09
then you should be able to control antibiotic resistance.
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然后你就有能力控制抗生素抗药性了。
10:11
And the idea is very simple.
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这个想法很简单。
10:12
If you've got a harmful organism,
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如果你有一个有害的病菌，
10:14
a high proportion of the people are going to be symptomatic,
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高比例的人会出现症状，
10:16
a high proportion of the people are going to be going to get antibiotics.
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高比例的人会有抗体。
10:18
You've got a lot of pressure favoring antibiotic resistance,
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在对抗生素的抗药性的促进上有很大的压力。
10:21
so you get increased virulence leading to
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因此增强的毒性导致了
10:23
the evolution of increased antibiotic resistance.
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（病菌对）抗生素的抗药性增强的进化。
10:25
And once you get increased antibiotic resistance,
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并且，一旦（病菌）对抗生素的抗药性增强，
10:28
the antibiotics aren't knocking out the harmful strains anymore.
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那么抗生素就不在能消灭有害的菌株了。
10:30
So, you've got a higher level of virulence.
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因此，你得到了更高级别的毒性。
10:32
So, you get this vicious cycle.
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这是个危险的循环。
10:34
The goal is to turn this around.
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我们的目标是使这种情况得到扭转。
10:36
If you could cause an evolutionary decrease in virulence
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如果你能通过清洁水源供应来促进
10:38
by cleaning up the water supply,
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毒性进化的衰减。
10:40
you should be able to get an evolutionary decrease
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那你就应该能使它们对抗生素的抗药性
10:42
in antibiotic resistance.
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的进化衰减。
10:44
So, we can go to the same countries and look and see.
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因此我们能去同样的国家，看一看。
10:46
Did Chile avoid the problem of antibiotic resistance,
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智利避免了抗生素的抗药性的问题么？
10:49
whereas did Ecuador actually have the beginnings of the problem?
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而厄瓜多尔实际上只是处于这一问题的初始阶段？
10:52
If we look in the beginning of the 1990s,
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如果我们看看九十年代初，
10:54
we see, again, a lot of variation.
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我们会又一次看到许多的变异。
10:56
In this case, on the Y-axis, we've just got a measure of antibiotic sensitivity --
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在这种情况下，在Y轴上我们会得到一个对抗生素敏感性的衡量。
11:00
and I won't go into that.
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我不准备详谈这些。
11:02
But we've got a lot of variation in antibiotic sensitivity in Chile,
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但在智利，我们发现了许多抗生素敏感性的变异。
11:05
Peru and Ecuador, and no trend across the years.
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秘鲁和厄瓜多尔，没有跨越数年的趋势。
11:07
But if we look at the end of the 1990s, just half a decade later,
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但如果我们看看90年代末，仅仅五年后，
11:11
we see that in Ecuador they started having a resistance problem.
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我们看到在厄瓜多尔，开始有抗药性的问题了。
11:14
Antibiotic sensitivity was going down.
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抗生素的敏感性在下降。
11:16
And in Chile, you still had antibiotic sensitivity.
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而在智利仍有抗生素敏感性。
11:19
So, it looks like Chile dodged two bullets.
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因此，看起来智利避免了两个问题。
11:21
They got the organism to evolve to mildness,
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他们使病菌进化的更温和，
11:23
and they got no development of antibiotic resistance.
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而且他们没有让病菌的抗药性进一步恶化。
11:26
Now, these ideas should apply across the board,
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现在这些观点应该被全面的应用。
11:29
as long as you can figure out why some organisms evolved to virulence.
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只要你能弄明白为什么一些病菌进化的更具毒性。
11:32
And I want to give you just one more example,
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我想仅仅再给出一个例子，
11:34
because we've talked a little bit about malaria.
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因为我们已经谈论了一下痢疾。
11:36
And the example I want to deal with is,
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而我想要给出的例子是，
11:38
or the idea I want to deal with, the question is,
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或者说我想提出的想法，问题是，
11:42
what can we do to try to get the malarial organism to evolve to mildness?
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为了使痢疾病菌进化的更加温和，我们能做什么？
11:45
Now, malaria's transmitted by a mosquito,
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现在，痢疾通过蚊子进行传播，
11:47
and normally if you're infected with malaria, and you're feeling sick,
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通常，如果你感染了痢疾，你会觉得不舒服，
11:51
it makes it even easier for the mosquito to bite you.
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这使得蚊子更容易叮你。
11:53
And you can show, just by looking at data from literature,
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而且，仅仅通过查看文献中的数据，你就会发现
11:56
that vector-borne diseases are more harmful
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通过虫媒传播的疾病比那些
11:58
than non-vector-borne diseases.
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通过非虫媒传播的疾病更加有害。
12:01
But I think there's a really fascinating example
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但我想有个真实的迷人的例子，
12:04
of what one can do experimentally to try to actually demonstrate this.
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人们可以做实验来尝试实际的去论证这些。
12:08
In the case of waterborne transmission,
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就水媒传播而言，
12:10
we'd like to clean up the water supplies,
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我们想通过清理水源供应，
12:12
see whether or not we can get those organisms to evolve towards mildness.
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来看看是否能使得这些病菌朝着温和的方向进化。
12:15
In the case of malaria, what we'd like to do is mosquito-proof houses.
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就痢疾而言，我们想做的是建造防蚊的房屋。
12:20
And the logic's a little more subtle here.
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这儿的逻辑有点更微妙了。
12:22
If you mosquito-proof houses,
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如果在防蚊的房屋里，
12:24
when people get sick, they're sitting in bed --
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当人们生病了，坐在床上时，
12:26
or in mosquito-proof hospitals, they're sitting in a hospital bed --
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或者在防蚊的医院中，人们坐在医院的床上时，
12:28
and the mosquitoes can't get to them.
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蚊子没法去叮咬他们。
12:30
So, if you're a harmful variant
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因此如果你是一个有害的病菌，
12:32
in a place where you've got mosquito-proof housing, then you're a loser.
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结果不得不待在一个防蚊的房子里，你就输了。
12:36
The only pathogens that get transmitted
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那些唯一能传播的病原体
12:39
are the ones that are infecting people that feel healthy enough
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是通过那些感染了却觉得自己很健康的人进行传播的，
12:41
to walk outside and get mosquito bites.
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他们走到外面，被蚊子叮咬了。
12:44
So, if you were to mosquito proof houses,
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那么，如果你在防蚊的房屋里，
12:46
you should be able to get these organisms to evolve to mildness.
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你就能够使得这些病菌进化的更温和。
12:48
And there's a really wonderful experiment that was done
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实际上我们已经作了一个非常棒的实验，
12:51
that suggests that we really should go ahead and do this.
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这实验说明我们应该来使用防蚊的房屋和医院。
12:54
And that experiment was done in Northern Alabama.
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这个实验室在北阿拉巴马进行的。
12:57
Just to give you a little perspective on this,
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仅仅给你一个关于这一实验的小观点，
12:59
I've given you a star at the intellectual center of the United States,
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我告诉你一个位于肯塔基的路易斯维尔的
13:03
which is right there in Louisville, Kentucky.
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美国知识产权中心的明星。
13:07
And this really cool experiment was done
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这个非常酷的实验是由田纳西流域管理局作的，
13:09
about 200 miles south of there, in Northern Alabama,
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实验地点是从这个中心向南大约200英里的地方，
13:12
by the Tennessee Valley Authority.
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就在北阿拉巴马。
13:13
They had dammed up the Tennessee River.
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他们阻塞了田纳西河。
13:16
They'd caused the water to back up,
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他们把水蓄积起来，
13:18
they needed electric, hydroelectric power.
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他们需要电力，水电。
13:21
And when you get stagnant water, you get mosquitoes.
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而当有一片死水的时候，就会出现蚊子。
13:23
They found in the late '30s -- 10 years after they'd made these dams --
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他们发现在最近30年代后期--在建造了这些大坝后的十年内--
13:27
that the people in Northern Alabama were infected with malaria,
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北阿拉巴马的人们感染了疟疾。
13:33
about a third to half of them were infected with malaria.
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大约三分之一到一半的人感染了疟疾。
13:36
This shows you the positions of some of these dams.
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这里显示了这些水库的位置。
13:39
OK, so the Tennessee Valley Authority was in a little bit of a bind.
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那好，田纳西流域管理局受到一点点限制。
13:43
There wasn't DDT, there wasn't chloroquines: what do they do?
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在那儿不能用滴滴涕，不能用氯喹，那么人们该怎么办？
13:47
Well, they decided to mosquito proof every house in Northern Alabama.
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好吧，他们决定让北阿拉巴马的每所房屋都能够防蚊。
13:50
So they did. They divided Northern Alabama into 11 zones,
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他们这么做了。他们把北阿拉巴马分成了11个区域，
13:53
and within three years, about 100 dollars per house,
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并且在三年内，每所房子花费大约100美元，
13:55
they mosquito proofed every house.
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他们对每所房子都进行了防蚊处理。
13:57
And these are the data.
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这儿是一些数据。
13:59
Every row across here represents one of those 11 zones.
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每个横跨这里的一行表示11个区域的其中之一。
14:03
And the asterisks represent the time at which
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这些星号表示防蚊措施实施
14:05
the mosquito proofing was complete.
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完成的时间。
14:07
And so what you can see is that
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那么你可以看到，
14:09
just the mosquito-proofed housing, and nothing else,
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仅仅是进行了房屋的防蚊处理，没有做别的，
14:12
caused the eradication of malaria.
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就根除了疟疾。
14:14
And this was, incidentally, published in 1949,
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而且这在1949年，偶然地发表在
14:16
in the leading textbook of malaria, called "Boyd's Malariology."
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关于疟疾最重要的名为"博伊德的痢疾学"的教科书中。
14:19
But almost no malaria experts even know it exists.
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但是几乎没有痢疾方面的专家知道它的存在。
14:22
This is important,
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这很重要，
14:24
because it tells us that if you have moderate biting densities,
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因为它告诉我们，如果在中等的叮咬密度下，
14:26
you can eradicate malaria by mosquito proofing houses.
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你用防蚊的房屋就能消除疟疾。
14:28
Now, I would suggest that you could do this in a lot of places.
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现在，我建议可以在许多地方这么做。
14:31
Like, you know, just as you get into the malaria zone,
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比如，你知道，正如你进入疟疾区，
14:35
sub-Saharan Africa.
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非洲的撒哈拉以南。
14:37
But as you move to really intense biting rate areas, like Nigeria,
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但是如果你去有十分强烈的叮咬率的区域，比如尼日利亚，
14:40
you're certainly not going to eradicate.
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你肯定不能根除它。
14:42
But that's when you should be favoring evolution towards mildness.
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但是你可以帮助它们变得更加温和。
14:46
So to me, it's an experiment that's waiting to happen,
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因此对我而言，这是个等待发生的实验，
14:49
and if it confirms the prediction, then
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而如果它确认了预测的结果，那么
14:51
we should have a very powerful tool.
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我们就会有了一个非常强有利的工具。
14:53
In a way, much more powerful than the kind of tools we're looking at,
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在某种程度上，它是比我们现在用的工具有力得多。
14:56
because most of what's being done today is
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因为如今我们能做的就是
14:58
to rely on things like anti-malarial drugs.
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依赖于像抗疟疾药似的东西。
15:00
And we know that, although it's great to make those
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而我们知道，虽然这能让这些抗疟疾药
15:03
anti-malarial drugs available at really low cost and high frequency,
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以实在的低价和高频率供应。
15:08
we know that when you make them highly available
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我们知道，当你不断用药时，
15:11
you're going to get resistance to those drugs.
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它们将对这些药产生抗药性。
15:13
And so it's a short-term solution.
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所以这是个短期的解决方案。
15:15
This is a long-term solution.
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这是个长期的解决方案。
15:17
What I'm suggesting here is that we could get evolution
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我的建议是，我们能让进化
15:19
working in the direction we want it to go,
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朝着我们希望的方向进行。
15:21
rather than always having to battle evolution as a problem
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而不总是与进化做斗争。
15:24
that stymies our efforts to control the pathogen,
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这是个问题因为它妨碍了我们对控制病原体做出的努力，
15:27
for example with anti-malarial drugs.
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例如抗疟疾药。
15:29
So, this table I've given just to emphasize
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因此，我给出的这张表仅仅是为了强调，
15:32
that I've only talked about two examples.
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我只是谈了两个例子。
15:35
But as I said earlier, this kind of logic applies across the board
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但如我之前所说，这类的逻辑应用贯穿整个
15:38
for infectious diseases, and it ought to.
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传染病领域，应该这样。
15:40
Because when we're dealing with infectious diseases, we're dealing with living systems.
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由于当我们应对传染病时，我们是在应对生命系统。
15:44
We're dealing with living systems;
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我们在应对生命系统，
15:46
we're dealing with systems that evolve.
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我们在应对一个可以进化的系统。
15:48
And so if you do something with those systems,
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而如果你对这样的系统做了些什么，
15:50
they're going to evolve one way or another.
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它们将朝着这个或那个方向进化。
15:52
And all I'm saying is that we need to figure out how they'll evolve,
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而所有我要说的是，我们需要弄明白它们如何进化，
15:55
so that -- we need to adjust our interventions
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以便于我们调整我们的干预措施，
15:57
to get the most bang for the intervention buck,
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来获得最大收益的干预措施，
16:00
so that we can get these organisms to evolve in the direction we want them to go.
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以便于我们能使这些病菌朝着我们期望的方向进化。
16:03
So, I don't really have time to talk about those things,
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所以，我真的没有时间来讨论这些事，
16:05
but I did want to put them up there,
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但我确实想要把它们放在这儿。
16:07
just to give you a sense that there really are solutions
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仅仅为了给你们一个感觉，我们确实有办法
16:10
to controlling the evolution of harmfulness
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来控制
16:13
of some of the nasty pathogens that we're confronted with.
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一些我们所面对的有害的病菌的进化。
16:19
And this links up with a lot of the other ideas that have been talked about.
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并且，这把许多之前讨论过的观点联系了起来。
16:23
So, for example, earlier today there was discussion of,
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那么，例如，今天早些时候的讨论，
16:28
how do you really lower sexual transmission of HIV?
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如何真正降低艾滋病毒的性传播？
16:34
What this emphasizes is that we need to figure out how it will work.
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需要强调的是我们需要清楚它是如何造成危害的。
16:37
Will it maybe get lowered if we alter the economy of the area?
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如果我们改变了这一区域的经济状况，它可能会降低么？
16:40
It may get lowered if we intervene in ways that
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它可能会降低，如果我们的干预措施
16:42
encourage people to stay more faithful to partners, and so on.
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鼓励人们对他们的伴侣更忠诚，等等。
16:46
But the key thing is to figure out how to lower it,
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但关键是明白如何降低它。
16:48
because if we lower it, we'll get an evolutionary change in the virus.
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因为如果我们降低它的话，我们将改变病毒的进化。
16:51
And the data really do support this:
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并且有数据的确实支持的，
16:53
that you actually do get the virus evolving towards mildness.
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如果你确实是让病毒朝着更加温和的方向进化。
16:56
And that will just add to the effectiveness of our control efforts.
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并且这将增加我们的控制投入的效率。
17:01
So the other thing I really like about this,
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因此，另一个我确实喜欢的部分是，
17:03
besides the fact that it brings a whole new dimension
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除了它会为疾病控制研究带来
17:05
into the study of control of disease,
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一个全新的领域之外，
17:09
is that often the kinds of interventions that you want,
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通常各种你想要的干预措施，
17:12
that it indicates should be done,
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这些应该做的干预措施，
17:14
are the kinds of interventions that people want anyhow.
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就是人们无论如何都想要的那些干预措施。
17:16
But people just haven't been able to justify the cost.
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但人们只是不能判断出所需付出的代价。
17:19
So, this is the kind of thing I'm talking about.
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因此，我所谈论的这类事情，
17:22
If we know that we're going to get extra bang for the buck from providing clean water,
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如果我们知道我们将会从提供清洁的水源中获得额外的好处，
17:25
then I think that we can say,
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那么我想，我们会说，
17:27
let's push the effort into that aspect of the control,
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让我们努力推进这方面的控制，
17:31
so that we can actually solve the problem,
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以便我们能真正的解决这个问题，
17:34
even though, if you just look at the frequency of infection,
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即使这样，如果你仅仅是看看这些感染的频率，
17:37
you would suggest that you can't solve the problem well enough
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你可能会觉得这个问题无法仅仅通过清理水源供应
17:41
just by cleaning up water supply.
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就可以很好的解决。
17:43
Anyhow, I'll end that there, and thank you very much.
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总之，我的演讲到此结束，非常感谢。
17:45
(Applause)
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（掌声）
ABOUT THE SPEAKER
Paul Ewald - Evolutionary biologistAfter years of studying illness from the germs' point of view, microbiologist Paul Ewald believes that Big Pharma is wrong about some very big issues. What's right? The leader in evolutionary medicine posits radical new approaches.
Why you should listen
Paul Ewald has a problem with modern medicine: It ignores the fact that many diseases of unknown origin can be linked to slow-growing infections caused by viruses, bacteria and other microorganisms.
Ewald -- whose theory stems from both a formal education in biological sciences, ecology, and evolution, and a personal bout with diarrhea in the 1970s -- aims to change this thinking. To that end, he has written popular news articles, academic papers, and two books (Evolution of Infectious Disease and Plague Time) that explain and expand his idea. Ewald is regarded as the leading expert in the emerging field of evolutionary medicine. He directs the evolutionary medicine program in the Biology department at the University of Louisville, Kentucky, and lectures worldwide.
Among other honors, Ewald was the first recipient of the Smithsonian Institution's George E. Burch Fellowship in Theoretic Medicine and Affiliated Sciences, which was established to foster pioneering work in health sciences.
Paul Ewald | Speaker | TED.com