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题目:Bird flu and the deteriorating environment VKl~oFKXJ
范文 l Z3&XTsq
Earlier this year, bird flu panic was in full swing: The French P# M<CG9
feared for their foie gras, the Swiss locked their chickens indoors, %a%+!wX0x
and Americans enlisted prison inmates in Alaska to help spot So3,Z'z=
infected wild birds. Iwd"f
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The H5N1 virus - previously confined to Southeast Asia - was >B|ofwm*
striking birds in places as diverse as Germany, Egypt, and Nigeria, R$~JhcX*l'
and a flu pandemic seemed inevitable. B)LXxdkOn
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Then the virus went quiet. Except for a steady stream of human cases qCv}+d)
in Indonesia, the current flu epicenter, the past year's worries |2+c D R
about a catastrophic global outbreak largely disappeared. x %!OP\
What happened? a
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Part of the explanation may be seasonal. Bird flu tends to be most QQ2OZy> W
active in the colder months, as the virus survives longer at low }1E_G
temperatures. e3bAT .P
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"Many of us are holding our breath to see what happens in the a-o
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winter," said Dr. Malik Peiris, a microbiology professor at Hong S
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Kong University. "H5N1 spread very rapidly last year," Peiris said. QyBK*uNdV
"So the question is, was that a one-off incident?" o7Z#,>`2
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Some experts suspect poultry vaccination has, paradoxically, w Lg:YM"
complicated detection. Vaccination reduces the amount of virus %[31ZFYB
circulating, but low levels of the virus may still be causing ^~hhdwu3a
outbreaks - without the obvious signs of dying birds. :+X2>Lu$FA
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"It's now harder to spot what's happening with the flu in animals *~MiL 9m+?
and humans," said Dr. Angus Nicoll, influenza director at the Xj&~N;Ysb
European Centres for Disease Control and Prevention. B[k+#Y YY
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While the pandemic has not materialized, experts say it's too early GqF.T #|
to relax. |'>E};D
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, Yk*57&QI
coordinator of the World Health Organization's global influenza Y+5A2Z)f[
program. But although the virus could mutate into a pandemic strain, (Os
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Fukuda points out that it might go the other direction instead, @XSu?+s)
becoming less dangerous for humans. ^_"q`71Dk
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H5N1 has primarily stalked Asia. This year, however, it crossed the 0jx~_zq-j
continental divide, infecting people in Turkey, Iraq, Egypt, . I9] `Q
Djibouti, and Azerbaijan.
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But despite the deaths of 154 people, and hundreds of millions of nfPl#]ef*
birds worldwide dying or being slaughtered, the virus still has not ClVpb e w
learned how to infect humans easily. fbbl92p
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Flu viruses constantly evolve, so the mere appearance of mutations *,=+R$
is not enough to raise alarm. The key is to identify which mutations > rX R;4%
are the most worrisome. 5 WNRo[`7
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"We don't really know how many changes this virus has got to make to .mU.eLM
adapt to humans, if it can at all," said Dr. Richard Webby, a bird A2FU}Ym0=
flu expert at St. Jude Children's Research Hospital in Tennessee. GZ>% &^E
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The most obvious sign that a pandemic may be under way will almost Nk~ dfY<s
certainly come from the field: a sudden spike in cases suggesting +W3>Yg%)X
human-to-human transmission. The last pandemic struck in 1968 - when UE;) mZ=l|
bird flu combined with a human strain and went on to kill 1 million uNGxz*e
people worldwide. $Lbe 5d?\
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In May, on Sumatra island in Indonesia, a cluster of eight cases was Yt<PKs#E
identified, six of whom died. The World Health Organization p?NjxQLA
immediately dispatched a team to investigate. >^ar$T;Ys
The U.N. agency was concerned enough by the reports to put D;n%sRq(Z
pharmaceuticals company Roche Holding AG on standby in case its 1@dx (_
global antiviral stockpile, promised to WHO for any operation to 0qUap*fvC
quash an emerging pandemic, needed to be rushed to Indonesia. )t=u(:u]
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Luckily, the Sumatra cluster was confined to a single family. Though <~*Ol+/
human-to-human transmission occurred - as it has in a handful of B\& Ka <r
other cases - the virus did not adapt enough to become easily lM%fgy X
infectious. j'x{j %U
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This highlighted many of the problems that continue to plague public Z!e q /
health officials, namely, patchy surveillance systems and limited u.FDe2|[ )
virus information. A\.*+k/B
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Even in China, where H5N1 has circulated the longest, surveillance <~+
is not ideal. VrxH6 Y
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"Monitoring the 14 billion birds in China, especially when most of Zw{tuO7}K
them are in back yards, is an enormous challenge," said Dr. Henk & 2igX?60
Bekedam, WHO's top official in China. Of the 21 human cases China -"H4brj;G
has logged so far, 20 were in areas without reported H5N1 outbreaks XCriZ|s
in birds. Q>yt O'v
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"We need to start looking harder for where the virus is hiding," 1D6O=j\
Bekedam said. Ti'kn{
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To better understand the virus' activity, it would help to have more 0&@ pX~h:
virus samples from every H5N1-affected country. But public health AoeW<}MO
authorities are at the mercy of governments and academics. QovC
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Scientists may hoard viruses while waiting for academic papers to be k;7.qhe:
published first. And developing countries may be wary of sharing ):
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virus samples if the vaccines that might be developed from them eS:e#> (
might ultimately be unaffordable. BH a>2N
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That leaves public health officials with an incomplete viral GR
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picture. P.DWC'IBN
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"It shouldn't just be WHO as a lonely voice in the desert, calling ArK9E!`^
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu Xs@ ^D,
expert with the Food and Agriculture Organization in Vietnam. All &y\2:IyA
countries, need to understand that sharing will help them better yfQE8 v+
prepare for a flu pandemic, he said. *`T &Dlt'8
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Though scientists are bracing themselves for increased bird flu \-w s[
activity in the winter, there are no predictions about where it )W|jt/
might appear next. The WHO's Fukuda said it would not be a surprise 8 f5^@K\c
to see it appear in new countries.
