請雙擊下方英文字幕播放視頻。
譯者: Adrienne Lin
審譯者: Zhu Jie
00:26
So I want to talk to you today about AIDS in sub-Saharan Africa.
0
26000
3000
我今天要講的是撒哈拉以南非洲的愛滋病情形
00:29
And this is a pretty well-educated audience,
1
29000
2000
各位教育程度都很高
00:31
so I imagine you all know something about AIDS.
2
31000
3000
所以大家應該都知道愛滋病
00:34
You probably know that roughly 25 million people in Africa
3
34000
2000
在非洲有2500萬人
00:36
are infected with the virus, that AIDS is a disease of poverty,
4
36000
4000
感染愛滋病病毒,而且它也是窮人的疾病
00:40
and that if we can bring Africa out of poverty, we would decrease AIDS as well.
5
40000
4000
如果能幫助非洲脫離貧窮,那愛滋病也會減少
00:44
If you know something more, you probably know that Uganda, to date,
6
44000
3000
還有,烏干達現在是撒哈拉以南非洲地區
00:47
is the only country in sub-Saharan Africa
7
47000
2000
唯一成功對抗這流行病
00:49
that has had success in combating the epidemic.
8
49000
3000
的國家
00:52
Using a campaign that encouraged people to abstain, be faithful, and use condoms --
9
52000
4000
他們宣導ABC運動:戒絕、忠貞、保險套
00:56
the ABC campaign -- they decreased their prevalence in the 1990s
10
56000
4000
成功在1990年,減低愛滋傳播率
01:00
from about 15 percent to 6 percent over just a few years.
11
60000
4000
幾年間,從15%降到6%
01:04
If you follow policy, you probably know that a few years ago
12
64000
3000
如果你關心政策,你應該知道幾年前
01:07
the president pledged 15 billion dollars to fight the epidemic over five years,
13
67000
4000
總統投入15億美元,對抗愛滋病
01:11
and a lot of that money is going to go to programs that try to replicate Uganda
14
71000
3000
大部分的資金,都投入類似烏干達的計畫
01:14
and use behavior change to encourage people and decrease the epidemic.
15
74000
6000
利用行為改變,來鼓勵人們,以減低傳染
01:20
So today I'm going to talk about some things
16
80000
2000
所以我今天要談一些
01:22
that you might not know about the epidemic,
17
82000
2000
關於愛滋,你們所不知道的事
01:24
and I'm actually also going to challenge
18
84000
2000
再來我要挑戰一些
01:26
some of these things that you think that you do know.
19
86000
2000
你們已知的事
01:28
To do that I'm going to talk about my research
20
88000
3000
我先談我身為經濟學家
01:31
as an economist on the epidemic.
21
91000
2000
對於愛滋病所做的研究
01:33
And I'm not really going to talk much about the economy.
22
93000
2000
我不會談太多經濟的東西
01:35
I'm not going to tell you about exports and prices.
23
95000
3000
也不會講進出口價格
01:38
But I'm going to use tools and ideas that are familiar to economists
24
98000
4000
但我要用一些經濟學家常用的方法
01:42
to think about a problem that's more traditionally
25
102000
2000
來解釋流行病學、公共衛生
01:44
part of public health and epidemiology.
26
104000
2000
衍生出的問題
01:46
And I think in that sense, this fits really nicely with this lateral thinking idea.
27
106000
4000
這樣很符合橫向思維的概念
01:50
Here I'm really using the tools of one academic discipline
28
110000
3000
運用一種學術領域的工具
01:53
to think about problems of another.
29
113000
2000
來解決其他領域的問題
01:55
So we think, first and foremost, AIDS is a policy issue.
30
115000
3000
首先,愛滋病跟政策有關
01:58
And probably for most people in this room, that's how you think about it.
31
118000
3000
可能在座大部分的人,也是這麼認為
02:01
But this talk is going to be about understanding facts about the epidemic.
32
121000
4000
但我要講的是,關於理解疫情傳播的事實
02:05
It's going to be about thinking about how it evolves, and how people respond to it.
33
125000
3000
關於思考它的形成原因,人們的反應
02:08
I think it may seem like I'm ignoring the policy stuff,
34
128000
3000
看來我可能會忽略政策之類的東西
02:11
which is really the most important,
35
131000
2000
雖然政策是最重要的
02:13
but I'm hoping that at the end of this talk you will conclude
36
133000
2000
但演講結束你會明白
02:15
that we actually cannot develop effective policy
37
135000
2000
除非了解疾病的傳播
02:17
unless we really understand how the epidemic works.
38
137000
3000
我們是無法訂定有效政策的
02:20
And the first thing that I want to talk about,
39
140000
2000
我想講的第一點
02:22
the first thing I think we need to understand is:
40
142000
2000
我們必須理解的第一點是
02:24
how do people respond to the epidemic?
41
144000
2000
人們對於愛滋病的反應是什麼?
02:26
So AIDS is a sexually transmitted infection, and it kills you.
42
146000
4000
愛滋病是性傳播疾病,會致死
02:30
So this means that in a place with a lot of AIDS,
43
150000
2000
所以愛滋病盛行的地方
02:32
there's a really significant cost of sex.
44
152000
2000
性行為的代價也高
02:34
If you're an uninfected man living in Botswana, where the HIV rate is 30 percent,
45
154000
4000
波紮那的病毒感染率30%,如果你是個健康的男人
02:38
if you have one more partner this year -- a long-term partner, girlfriend, mistress --
46
158000
4000
你今年多了一個性伴侶-長期的、女友、情婦也好
02:42
your chance of dying in 10 years increases by three percentage points.
47
162000
4000
你十年內死亡率會提高三個百分點
02:46
That is a huge effect.
48
166000
2000
這是很驚人的
02:48
And so I think that we really feel like then people should have less sex.
49
168000
3000
所以我們會覺得,人們真的要減少性行為
02:51
And in fact among gay men in the US
50
171000
2000
事實上,美國的同性戀中
02:53
we did see that kind of change in the 1980s.
51
173000
2000
在1980年代,我們確實看到這種改變
02:55
So if we look in this particularly high-risk sample, they're being asked,
52
175000
4000
仔細觀察高危險群,當他們被問到:
02:59
"Did you have more than one unprotected sexual partner in the last two months?"
53
179000
3000
「過去的兩個月內,你是否有一個以上,未採取保護措施的性伴侶?」
03:02
Over a period from '84 to '88, that share drops from about 85 percent to 55 percent.
54
182000
6000
數據顯示,從84到88年,比例從85%下降到55%
03:08
It's a huge change in a very short period of time.
55
188000
2000
這麼短時間內,這是很大的改變
03:10
We didn't see anything like that in Africa.
56
190000
2000
在非洲我們從未看到這樣的改變
03:12
So we don't have quite as good data, but you can see here
57
192000
3000
我們沒有足夠的數據,但你可以看到
03:15
the share of single men having pre-marital sex,
58
195000
2000
這是單身男人婚前性行為
03:17
or married men having extra-marital sex,
59
197000
2000
或已婚男人的婚外性行為的數據比例
03:19
and how that changes from the early '90s to late '90s,
60
199000
3000
從90年代初期到末期的改變
03:22
and late '90s to early 2000s. The epidemic is getting worse.
61
202000
3000
以及90年末到2000年初期的改變,疫情變嚴重了
03:25
People are learning more things about it.
62
205000
2000
人們對疾病的瞭解更多
03:27
We see almost no change in sexual behavior.
63
207000
2000
但性行為上卻幾乎沒有變化
03:29
These are just tiny decreases -- two percentage points -- not significant.
64
209000
4000
只有降低極少的2%而已
03:33
This seems puzzling. But I'm going to argue that you shouldn't be surprised by this,
65
213000
4000
看來很怪,但你不應該對此感到吃驚
03:37
and that to understand this you need to think about health
66
217000
3000
想要理解原因,你要用經濟學家的思維
03:40
the way than an economist does -- as an investment.
67
220000
3000
來思考健康議題,用投資的概念
03:43
So if you're a software engineer and you're trying to think about
68
223000
3000
如果你是個軟體設計師,當你在想
03:46
whether to add some new functionality to your program,
69
226000
3000
是否要在你的設計裡,加一些新的功能時
03:49
it's important to think about how much it costs.
70
229000
2000
成本是必須考慮的
03:51
It's also important to think about what the benefit is.
71
231000
2000
收益也是必須考慮的
03:53
And one part of that benefit is how much longer
72
233000
2000
考慮收益的其中一個方法就是
03:55
you think this program is going to be active.
73
235000
2000
你的軟體離推出還有多久
03:57
If version 10 is coming out next week,
74
237000
2000
如果第十版下週推出
03:59
there's no point in adding more functionality into version nine.
75
239000
3000
那就沒必要更新第九版
04:02
But your health decisions are the same.
76
242000
2000
而健康也是如此
04:04
Every time you have a carrot instead of a cookie,
77
244000
2000
每次放棄餅乾而去吃胡蘿蔔時
04:06
every time you go to the gym instead of going to the movies,
78
246000
3000
每次去健身房而不是看電影時
04:09
that's a costly investment in your health.
79
249000
2000
就是你對健康極大的投資
04:11
But how much you want to invest is going to depend
80
251000
2000
但你要投資多少
04:13
on how much longer you expect to live in the future,
81
253000
2000
跟你能活多久有關
04:15
even if you don't make those investments.
82
255000
2000
有沒有投資都一樣
04:17
AIDS is the same kind of thing. It's costly to avoid AIDS.
83
257000
3000
愛滋病也是如此,防疫愛滋也是昂貴的
04:20
People really like to have sex.
84
260000
3000
大家都喜歡做愛
04:23
But, you know, it has a benefit in terms of future longevity.
85
263000
6000
以未來長壽來講,它確實有好處
04:29
But life expectancy in Africa, even without AIDS, is really, really low:
86
269000
4000
但在非洲,即使沒有愛滋病,平均壽命還是很低
04:33
40 or 50 years in a lot of places.
87
273000
3000
大部分地方是40到50歲
04:36
I think it's possible, if we think about that intuition, and think about that fact,
88
276000
4000
這樣可以馬上理解
04:40
that maybe that explains some of this low behavior change.
89
280000
3000
低行為改變的原因了
04:43
But we really need to test that.
90
283000
2000
但仍需要證實
04:45
And a great way to test that is to look across areas in Africa and see:
91
285000
3000
證實的方法就是,看非洲地區
04:48
do people with more life expectancy change their sexual behavior more?
92
288000
4000
平均壽命高的地方,性行為是否有較大的改變?
04:52
And the way that I'm going to do that is,
93
292000
2000
我的作法是
04:54
I'm going to look across areas with different levels of malaria.
94
294000
3000
調查不同程度的瘧疾地區
04:57
So malaria is a disease that kills you.
95
297000
3000
瘧疾也是會致命的疾病
05:00
It's a disease that kills a lot of adults in Africa, in addition to a lot of children.
96
300000
3000
在非洲,無數的大人、小孩因此死亡
05:03
And so people who live in areas with a lot of malaria
97
303000
3000
所以住在瘧疾病率高地區的人
05:06
are going to have lower life expectancy than people who live in areas with limited malaria.
98
306000
4000
平均壽命低於瘧疾不嚴重地區的人
05:10
So one way to test to see whether we can explain
99
310000
2000
所以我們研究
05:12
some of this behavior change by differences in life expectancy
100
312000
3000
壽命是否會影響行為改變的方法
05:15
is to look and see is there more behavior change
101
315000
3000
就是觀察瘧疾病率低的地區
05:18
in areas where there's less malaria.
102
318000
2000
是否有較大的行為改變
05:20
So that's what this figure shows you.
103
320000
2000
這是我們的數據
05:22
This shows you -- in areas with low malaria, medium malaria, high malaria --
104
322000
4000
分別是低、中、高程度瘧疾病率的地區
05:26
what happens to the number of sexual partners as you increase HIV prevalence.
105
326000
4000
當愛滋病毒傳播增加時,性伴侶的數量情形
05:30
If you look at the blue line,
106
330000
2000
看這條藍線
05:32
the areas with low levels of malaria, you can see in those areas,
107
332000
3000
在這些瘧疾較少的地區
05:35
actually, the number of sexual partners is decreasing a lot
108
335000
3000
當愛滋病毒傳播率提高時
05:38
as HIV prevalence goes up.
109
338000
2000
性伴侶數量是大量減少的
05:40
Areas with medium levels of malaria it decreases some --
110
340000
2000
中程度瘧疾地區
05:42
it doesn't decrease as much. And areas with high levels of malaria --
111
342000
3000
雖然也有減少但不明顯,高程度瘧疾地區
05:45
actually, it's increasing a little bit, although that's not significant.
112
345000
5000
反而增加,雖然數目不大
05:50
This is not just through malaria.
113
350000
2000
還不只是瘧疾
05:52
Young women who live in areas with high maternal mortality
114
352000
3000
高產婦死亡率地區的年輕婦女
05:55
change their behavior less in response to HIV
115
355000
3000
為了防止愛滋病毒所做的行為改變
05:58
than young women who live in areas with low maternal mortality.
116
358000
3000
比低產婦死亡率地區的年輕婦女還少
06:01
There's another risk, and they respond less to this existing risk.
117
361000
4000
因為有其他風險,所以他們對於已知風險的反應不大
06:06
So by itself, I think this tells a lot about how people behave.
118
366000
3000
這解釋了許多人類的行為
06:09
It tells us something about why we see limited behavior change in Africa.
119
369000
3000
像是為什麼非洲的行為改變有限
06:12
But it also tells us something about policy.
120
372000
2000
但還有政策的成效
06:14
Even if you only cared about AIDS in Africa,
121
374000
3000
即使你只關心在非洲的愛滋病情況
06:17
it might still be a good idea to invest in malaria,
122
377000
3000
一起投資改善瘧疾、
06:20
in combating poor indoor air quality,
123
380000
2000
室內的空氣品質、
06:22
in improving maternal mortality rates.
124
382000
2000
降低產婦死亡率也是很重要的
06:24
Because if you improve those things,
125
384000
2000
因為改變了這些
06:26
then people are going to have an incentive to avoid AIDS on their own.
126
386000
4000
人們就會自覺性的防治愛滋病
06:30
But it also tells us something about one of these facts that we talked about before.
127
390000
4000
這也證實我們先前所提的
06:34
Education campaigns, like the one that the president is focusing on in his funding,
128
394000
4000
總統一直投入資金的教育活動
06:38
may not be enough, at least not alone.
129
398000
2000
是不夠的
06:40
If people have no incentive to avoid AIDS on their own,
130
400000
2000
如果他們沒有防治愛滋病的自覺
06:42
even if they know everything about the disease,
131
402000
2000
就算他們了解這疾病
06:44
they still may not change their behavior.
132
404000
2000
還是不會改變他們的行為
06:46
So the other thing that I think we learn here is that AIDS is not going to fix itself.
133
406000
3000
我們知道愛滋不會自癒
06:49
People aren't changing their behavior enough
134
409000
2000
就算人們改變行為
06:51
to decrease the growth in the epidemic.
135
411000
3000
傳染率降幅也不大
06:54
So we're going to need to think about policy
136
414000
2000
我們要重新考慮政策
06:56
and what kind of policies might be effective.
137
416000
2000
找出更有效的政策
06:58
And a great way to learn about policy is to look at what worked in the past.
138
418000
3000
了解政策的方法,可以從過去的情形來看
07:01
The reason that we know that the ABC campaign
139
421000
2000
我們知道,ABC運動
07:03
was effective in Uganda is we have good data on prevalence over time.
140
423000
3000
在烏干達這麼有效的原因,是因為當時有數據
07:06
In Uganda we see the prevalence went down.
141
426000
2000
可以看出傳染率下降
07:08
We know they had this campaign. That's how we learn about what works.
142
428000
3000
我們知道是ABC運動的關係,所以做出此結論
07:11
It's not the only place we had any interventions.
143
431000
2000
但不只有烏干達有活動
07:13
Other places have tried things, so why don't we look at those places
144
433000
4000
其他地方也有政策,那我們怎麼
07:17
and see what happened to their prevalence?
145
437000
3000
不看看那些地方的情形呢?
07:20
Unfortunately, there's almost no good data
146
440000
2000
不幸的,我們並沒有2003年
07:22
on HIV prevalence in the general population in Africa until about 2003.
147
442000
5000
非洲普遍人口的愛滋病毒感染情形
07:27
So if I asked you, "Why don't you go and find me
148
447000
2000
所以如果要找布基那法索國
07:29
the prevalence in Burkina Faso in 1991?"
149
449000
3000
1991年傳染率數據
07:32
You get on Google, you Google, and you find,
150
452000
3000
用Google查一下,你會發現
07:35
actually the only people tested in Burkina Faso in 1991
151
455000
3000
1991年布基那法索國受測者
07:38
are STD patients and pregnant women,
152
458000
2000
都是性病患者和懷孕婦女
07:40
which is not a terribly representative group of people.
153
460000
2000
這群受測對象還可以
07:42
Then if you poked a little more, you looked a little more at what was going on,
154
462000
3000
但如果深入調查,你會發現
07:45
you'd find that actually that was a pretty good year,
155
465000
3000
當年的結果是不錯的
07:48
because in some years the only people tested are IV drug users.
156
468000
3000
其他年的受測對象都是靜脈藥癮者
07:51
But even worse -- some years it's only IV drug users,
157
471000
2000
更糟的是,有些年是測靜脈藥癮者
07:53
some years it's only pregnant women.
158
473000
2000
有些年只有測懷孕婦女
07:55
We have no way to figure out what happened over time.
159
475000
2000
根本無法得知當時情形
07:57
We have no consistent testing.
160
477000
2000
也沒有持續抽樣檢察
07:59
Now in the last few years, we actually have done some good testing.
161
479000
5000
但幾年後,我們確實做了一些抽檢
08:04
In Kenya, in Zambia, and a bunch of countries,
162
484000
3000
在肯亞、尚比亞和一些國家
08:07
there's been testing in random samples of the population.
163
487000
3000
都有一些隨機抽樣
08:10
But this leaves us with a big gap in our knowledge.
164
490000
3000
但數據上還是留了很大一片空白
08:13
So I can tell you what the prevalence was in Kenya in 2003,
165
493000
3000
我能告訴你,肯亞2003年的感染情況
08:16
but I can't tell you anything about 1993 or 1983.
166
496000
3000
但我無法提供1993年或1983年的情況
08:19
So this is a problem for policy. It was a problem for my research.
167
499000
4000
這是政策的問題,也是我研究遇到的問題
08:23
And I started thinking about how else might we figure out
168
503000
4000
所以我開始想其他可能的辦法
08:27
what the prevalence of HIV was in Africa in the past.
169
507000
2000
以獲得非洲過去的愛滋病毒傳染率數據
08:29
And I think that the answer is, we can look at mortality data,
170
509000
4000
我想到的方法是,利用死亡率數據
08:33
and we can use mortality data to figure out what the prevalence was in the past.
171
513000
4000
來算出過去的愛滋病毒傳染率
08:37
To do this, we're going to have to rely on the fact
172
517000
2000
所以我們只能用愛滋病
08:39
that AIDS is a very specific kind of disease.
173
519000
2000
有個獨特性-
08:41
It kills people in the prime of their lives.
174
521000
2000
會在人類黃金時期致死-這點
08:43
Not a lot of other diseases have that profile. And you can see here --
175
523000
3000
其他疾病都沒有這個特點,所以可以看到:
08:46
this is a graph of death rates by age in Botswana and Egypt.
176
526000
4000
這是波紮那和埃及的死亡率,以年齡劃分
08:50
Botswana is a place with a lot of AIDS,
177
530000
2000
波紮那是愛滋盛行的地區
08:52
Egypt is a place without a lot of AIDS.
178
532000
2000
埃及是愛滋不盛行的地區
08:54
And you see they have pretty similar death rates among young kids and old people.
179
534000
3000
他們的兒童、老人死亡率相似
08:57
That suggests it's pretty similar levels of development.
180
537000
3000
表示他們有相似的發展水準
09:00
But in this middle region, between 20 and 45,
181
540000
3000
但在20到45歲間的死亡率
09:03
the death rates in Botswana are much, much, much higher than in Egypt.
182
543000
4000
波紮那死亡率高出埃及很多
09:07
But since there are very few other diseases that kill people,
183
547000
4000
但其他會致死的並不多
09:11
we can really attribute that mortality to HIV.
184
551000
3000
我們能將死亡率歸因為愛滋
09:14
But because people who died this year of AIDS got it a few years ago,
185
554000
4000
但愛滋感染到死亡的期間很長
09:18
we can use this data on mortality to figure out what HIV prevalence was in the past.
186
558000
5000
我們就用死亡率推回幾年前愛滋傳染率
09:23
So it turns out, if you use this technique,
187
563000
2000
所以,用這方法
09:25
actually your estimates of prevalence are very close
188
565000
2000
我們能估算,受測結果
09:27
to what we get from testing random samples in the population,
189
567000
3000
與估計的愛滋傳染率是很接近的
09:30
but they're very, very different than what UNAIDS tells us the prevalences are.
190
570000
5000
但卻與聯合國愛滋病規劃署(UNAIDS)提供的數據大不相同
09:35
So this is a graph of prevalence estimated by UNAIDS,
191
575000
3000
這是UNAIDS的傳染率統計
09:38
and prevalence based on the mortality data
192
578000
2000
以及1990年後期非洲九國
09:40
for the years in the late 1990s in nine countries in Africa.
193
580000
4000
的死亡率數據
09:44
You can see, almost without exception,
194
584000
2000
可以看出,幾乎沒有例外
09:46
the UNAIDS estimates are much higher than the mortality-based estimates.
195
586000
4000
UNAIDS的估計高出死亡率估計許多
09:50
UNAIDS tell us that the HIV rate in Zambia is 20 percent,
196
590000
4000
UNAIDS說尚比亞愛滋傳播率20%
09:54
and mortality estimates suggest it's only about 5 percent.
197
594000
4000
但死亡率估計只有5%
09:58
And these are not trivial differences in mortality rates.
198
598000
3000
這種差距是很大的
10:01
So this is another way to see this.
199
601000
2000
從另一方向來看
10:03
You can see that for the prevalence to be as high as UNAIDS says,
200
603000
2000
如果傳播率有UNAIDS說的這麼高
10:05
we have to really see 60 deaths per 10,000
201
605000
2000
那死亡率應為1萬名中有60人死亡
10:07
rather than 20 deaths per 10,000 in this age group.
202
607000
4000
而不是1萬名有20人死亡的比例
10:11
I'm going to talk a little bit in a minute
203
611000
2000
我想用一分鐘稍微來談
10:13
about how we can use this kind of information to learn something
204
613000
3000
我們要怎麼用這種知識
10:16
that's going to help us think about the world.
205
616000
2000
來解決現有的問題
10:18
But this also tells us that one of these facts
206
618000
2000
我也會談到,演講開始時
10:20
that I mentioned in the beginning may not be quite right.
207
620000
3000
提到的某一點,其實是錯誤的
10:23
If you think that 25 million people are infected,
208
623000
2000
如果250萬人感染,
10:25
if you think that the UNAIDS numbers are much too high,
209
625000
3000
或者UNAIDS估計太高,
10:28
maybe that's more like 10 or 15 million.
210
628000
2000
那說... 100-150萬好了
10:30
It doesn't mean that AIDS isn't a problem. It's a gigantic problem.
211
630000
4000
這樣估計不表示愛滋不是問題,愛滋很嚴重
10:34
But it does suggest that that number might be a little big.
212
634000
4000
但這表示數字有點灌水了
10:38
What I really want to do, is I want to use this new data
213
638000
2000
我希望做的是,利用這新數據
10:40
to try to figure out what makes the HIV epidemic grow faster or slower.
214
640000
4000
來解答愛滋病毒傳播快慢的原因
10:44
And I said in the beginning, I wasn't going to tell you about exports.
215
644000
3000
如我一開始說的,我不談進出口
10:47
When I started working on these projects,
216
647000
2000
但我做了一些計畫
10:49
I was not thinking at all about economics,
217
649000
2000
雖然不是以經濟為出發點
10:51
but eventually it kind of sucks you back in.
218
651000
3000
但最後總會回到經濟來
10:54
So I am going to talk about exports and prices.
219
654000
3000
我要說的是進出口價格
10:57
And I want to talk about the relationship between economic activity,
220
657000
3000
各國的經濟活動、出口量以及
11:00
in particular export volume, and HIV infections.
221
660000
4000
愛滋病毒感染的關係
11:04
So obviously, as an economist, I'm deeply familiar
222
664000
4000
身為經濟學家,我明白
11:08
with the fact that development, that openness to trade,
223
668000
2000
對於發展中國家來說
11:10
is really good for developing countries.
224
670000
2000
出口發展、自由是很重要的
11:12
It's good for improving people's lives.
225
672000
3000
可以促進生活品質
11:15
But openness and inter-connectedness, it comes with a cost
226
675000
2000
但以疾病角度來說
11:17
when we think about disease. I don't think this should be a surprise.
227
677000
3000
這種自由與交流是有代價的
11:20
On Wednesday, I learned from Laurie Garrett
228
680000
2000
星期三,蓋瑞特(全球衛生研究員)說
11:22
that I'm definitely going to get the bird flu,
229
682000
2000
我一定會得禽流感
11:24
and I wouldn't be at all worried about that
230
684000
3000
但要是我們和亞洲沒有接觸
11:27
if we never had any contact with Asia.
231
687000
3000
根本不必擔心
11:30
And HIV is actually particularly closely linked to transit.
232
690000
4000
而愛滋病毒與運輸是緊密相連的
11:34
The epidemic was introduced to the US
233
694000
2000
愛滋當時傳到美國
11:36
by actually one male steward on an airline flight,
234
696000
4000
其實是因為飛機上一名男空服員
11:40
who got the disease in Africa and brought it back.
235
700000
2000
從非洲將病毒帶回來
11:42
And that was the genesis of the entire epidemic in the US.
236
702000
3000
也是美國愛滋病的開端
11:45
In Africa, epidemiologists have noted for a long time
237
705000
4000
在非洲,病理學家很早之前就發現
11:49
that truck drivers and migrants are more likely to be infected than other people.
238
709000
4000
移民者、卡車司機的感染率高於其他人
11:53
Areas with a lot of economic activity --
239
713000
2000
如果該地有很多經濟活動、
11:55
with a lot of roads, with a lot of urbanization --
240
715000
3000
很多道路、非常都市化
11:58
those areas have higher prevalence than others.
241
718000
2000
那麼傳染率則較普及
12:00
But that actually doesn't mean at all
242
720000
2000
但也不代表
12:02
that if we gave people more exports, more trade, that that would increase prevalence.
243
722000
4000
如果有更多交易、出口,就會增加感染率
12:06
By using this new data, using this information about prevalence over time,
244
726000
4000
利用這個傳染率的數據
12:10
we can actually test that. And so it seems to be --
245
730000
4000
我們可以測試看看
12:14
fortunately, I think -- it seems to be the case
246
734000
2000
結果證明是對的
12:16
that these things are positively related.
247
736000
2000
這些東西是相互關聯的
12:18
More exports means more AIDS. And that effect is really big.
248
738000
4000
越多出口、越多愛滋,影響極大
12:22
So the data that I have suggests that if you double export volume,
249
742000
4000
數據顯示,如果出口數加一倍
12:26
it will lead to a quadrupling of new HIV infections.
250
746000
5000
愛滋感染率會增加四倍
12:31
So this has important implications both for forecasting and for policy.
251
751000
3000
因此在預測、政策上都要將此納入考量
12:34
From a forecasting perspective, if we know where trade is likely to change,
252
754000
4000
從預測的角度來看,如果我們知道交易會改變
12:38
for example, because of the African Growth and Opportunities Act
253
758000
3000
例如,因為「非洲成長及機會法案」
12:41
or other policies that encourage trade,
254
761000
2000
或其他鼓勵交易的法案
12:43
we can actually think about which areas are likely to be heavily infected with HIV.
255
763000
5000
我們可以知道這些地方感染率會提高
12:48
And we can go and we can try to have pre-emptive preventive measures there.
256
768000
6000
那就可以先發製人,做出因應措施
12:54
Likewise, as we're developing policies to try to encourage exports,
257
774000
3000
相同的,現在許多政策都鼓勵出口
12:57
if we know there's this externality --
258
777000
2000
如果我們知道會有外部效應-
12:59
this extra thing that's going to happen as we increase exports --
259
779000
2000
增加出口連帶其他事情的發生
13:01
we can think about what the right kinds of policies are.
260
781000
3000
即可想出正確的因應政策
13:04
But it also tells us something about one of these things that we think that we know.
261
784000
3000
有些事我們早已清楚
13:07
Even though it is the case that poverty is linked to AIDS,
262
787000
3000
即使我們知道愛滋與貧窮習習相關
13:10
in the sense that Africa is poor and they have a lot of AIDS,
263
790000
3000
非洲窮、愛滋多
13:13
it's not necessarily the case that improving poverty -- at least in the short run,
264
793000
4000
短期來說,不表示改善經濟
13:17
that improving exports and improving development --
265
797000
2000
改善出口、改善當地發展
13:19
it's not necessarily the case that that's going to lead
266
799000
2000
就能有效的
13:21
to a decline in HIV prevalence.
267
801000
2000
降低愛滋病毒盛行率
13:24
So throughout this talk I've mentioned a few times
268
804000
2000
剛剛我重複提了
13:26
the special case of Uganda, and the fact that
269
806000
2000
烏干達成功的案例
13:28
it's the only country in sub-Saharan Africa with successful prevention.
270
808000
4000
它是撒哈拉以南非洲唯一成功預防傳染的國家
13:32
It's been widely heralded.
271
812000
2000
結果大家都開心
13:34
It's been replicated in Kenya, and Tanzania, and South Africa and many other places.
272
814000
6000
相同政策也在肯亞、坦尚尼亞、南非等國實施
13:40
But now I want to actually also question that.
273
820000
4000
但我懷疑它的成效
13:44
Because it is true that there was a decline in prevalence
274
824000
3000
因為1990年代,烏干達愛滋傳播率降低
13:47
in Uganda in the 1990s. It's true that they had an education campaign.
275
827000
4000
一半是因為有教育性的活動
13:51
But there was actually something else that happened in Uganda in this period.
276
831000
6000
但事實上,烏干達當時發生了一件事
13:57
There was a big decline in coffee prices.
277
837000
2000
就是咖啡價格降低
13:59
Coffee is Uganda's major export.
278
839000
2000
烏干達主要出口是咖啡
14:01
Their exports went down a lot in the early 1990s -- and actually that decline lines up
279
841000
5000
1990年代早期,出口是下降的,可以看出
14:06
really, really closely with this decline in new HIV infections.
280
846000
4000
下降幅度與愛滋病毒感染幅度極為相同
14:10
So you can see that both of these series --
281
850000
3000
可以從圖上明顯看出
14:13
the black line is export value, the red line is new HIV infections --
282
853000
3000
黑線是出口數,紅線是愛滋病毒感染率
14:16
you can see they're both increasing.
283
856000
2000
兩個都增加
14:18
Starting about 1987 they're both going down a lot.
284
858000
2000
從1987年開始,大幅下滑
14:20
And then actually they track each other
285
860000
2000
最後幾年
14:22
a little bit on the increase later in the decade.
286
862000
2000
兩個數據又同時上升
14:24
So if you combine the intuition in this figure
287
864000
2000
所以用你的直覺以及
14:26
with some of the data that I talked about before,
288
866000
3000
利用我剛剛的數據可以看出
14:29
it suggests that somewhere between 25 percent and 50 percent
289
869000
4000
烏干達傳染率的下降
14:33
of the decline in prevalence in Uganda
290
873000
2000
有25%到50%
14:35
actually would have happened even without any education campaign.
291
875000
4000
就算沒有教育活動也會減少
14:39
But that's enormously important for policy.
292
879000
2000
這對於後來政策制定很重要
14:41
We're spending so much money to try to replicate this campaign.
293
881000
2000
我們花了這麼多錢投入ABC運動
14:43
And if it was only 50 percent as effective as we think that it was,
294
883000
3000
但只有我們預期一半的效果
14:46
then there are all sorts of other things
295
886000
2000
所以或許我們應該
14:48
maybe we should be spending our money on instead.
296
888000
2000
想想更多錢應該怎麼花的方法
14:50
Trying to change transmission rates by treating other sexually transmitted diseases.
297
890000
4000
像是治療其他性傳染疾病還控制傳染率
14:54
Trying to change them by engaging in male circumcision.
298
894000
2000
像是鼓勵男性割包皮
14:56
There are tons of other things that we should think about doing.
299
896000
2000
還有更多的事可以做
14:58
And maybe this tells us that we should be thinking more about those things.
300
898000
4000
我想說的是,希望大家能想些其他能做的事
15:02
I hope that in the last 16 minutes I've told you something that you didn't know about AIDS,
301
902000
5000
我希望剛剛16分鐘內,我分享了你們所不知道的事
15:07
and I hope that I've gotten you questioning a little bit
302
907000
2000
我希望各位能深入思考
15:09
some of the things that you did know.
303
909000
2000
那些你們已知的事
15:11
And I hope that I've convinced you maybe
304
911000
2000
我希望我成功說服你們
15:13
that it's important to understand things about the epidemic
305
913000
2000
思考政策時
15:15
in order to think about policy.
306
915000
2000
了解疾病是很重要的
15:18
But more than anything, you know, I'm an academic.
307
918000
2000
但是,我是一個學者
15:20
And when I leave here, I'm going to go back
308
920000
2000
當演講結束,我會回到
15:22
and sit in my tiny office, and my computer, and my data.
309
922000
3000
我的小辦公室,對著我的電腦、數據
15:25
And the thing that's most exciting about that
310
925000
2000
而我最興奮的事
15:27
is every time I think about research, there are more questions.
311
927000
3000
我每次想到研究,我就會有更多的問題
15:30
There are more things that I think that I want to do.
312
930000
2000
我想做的還有很多
15:32
And what's really, really great about being here
313
932000
2000
能來這裡真的很棒
15:34
is I'm sure that the questions that you guys have
314
934000
2000
我相信你們所思考的問題
15:36
are very, very different than the questions that I think up myself.
315
936000
3000
都和我所想出的問題截然不同
15:39
And I can't wait to hear about what they are.
316
939000
2000
而我非常期待你們想出的問題
15:41
So thank you very much.
317
941000
2000
謝謝大家
New videos
Original video on YouTube.com
關於本網站
本網站將向您介紹對學習英語有用的 YouTube 視頻。 您將看到來自世界各地的一流教師教授的英語課程。 雙擊每個視頻頁面上顯示的英文字幕,從那裡播放視頻。 字幕與視頻播放同步滾動。 如果您有任何意見或要求,請使用此聯繫表與我們聯繫。