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题目:Bird flu and the deteriorating environment Y`@:L' j
范文 l >;Er[Rywr
Earlier this year, bird flu panic was in full swing: The French >"qnuv G
feared for their foie gras, the Swiss locked their chickens indoors, *QAcp` ;*
and Americans enlisted prison inmates in Alaska to help spot
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infected wild birds. %u"3&kOV
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The H5N1 virus - previously confined to Southeast Asia - was 3DH}
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striking birds in places as diverse as Germany, Egypt, and Nigeria, _hgu:
and a flu pandemic seemed inevitable. h$`P|#V&
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Then the virus went quiet. Except for a steady stream of human cases W0GDn
in Indonesia, the current flu epicenter, the past year's worries Q/EH vb]
about a catastrophic global outbreak largely disappeared. m44Ab6gpsb
What happened? P@ Oq'y[
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Part of the explanation may be seasonal. Bird flu tends to be most E<u6 js,
active in the colder months, as the virus survives longer at low `Pa z
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"Many of us are holding our breath to see what happens in the NRU&GCVwu
winter," said Dr. Malik Peiris, a microbiology professor at Hong cE3g7(a
Kong University. "H5N1 spread very rapidly last year," Peiris said. L4bx [
"So the question is, was that a one-off incident?" i7hWBd4wK
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Some experts suspect poultry vaccination has, paradoxically, Z(F`M;1>xI
complicated detection. Vaccination reduces the amount of virus @L Qe[`
circulating, but low levels of the virus may still be causing 6_`9
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outbreaks - without the obvious signs of dying birds. C"`,?K(U
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"It's now harder to spot what's happening with the flu in animals l42 3+vo
and humans," said Dr. Angus Nicoll, influenza director at the ~?l>QP|o
European Centres for Disease Control and Prevention. ''Lf6S`4X~
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While the pandemic has not materialized, experts say it's too early "UUzLa_
to relax. 9|y?jb5im
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, 5
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coordinator of the World Health Organization's global influenza {<f |h)r
program. But although the virus could mutate into a pandemic strain, * qM)[XO
Fukuda points out that it might go the other direction instead, ZdcG6IG+
becoming less dangerous for humans. }:6$5/?
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H5N1 has primarily stalked Asia. This year, however, it crossed the }q-* L s
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continental divide, infecting people in Turkey, Iraq, Egypt, t@hE}R
Djibouti, and Azerbaijan. Cp[{| U-?G
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But despite the deaths of 154 people, and hundreds of millions of H_ecb;|m P
birds worldwide dying or being slaughtered, the virus still has not st91r V$y?
learned how to infect humans easily. aaa6R|>0
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Flu viruses constantly evolve, so the mere appearance of mutations S .i CkX
is not enough to raise alarm. The key is to identify which mutations [PR Qa[_
are the most worrisome. i
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"We don't really know how many changes this virus has got to make to ^seb8o7
adapt to humans, if it can at all," said Dr. Richard Webby, a bird Ms
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flu expert at St. Jude Children's Research Hospital in Tennessee. ;s$bVGHr
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The most obvious sign that a pandemic may be under way will almost iS/fa Xe5
certainly come from the field: a sudden spike in cases suggesting cV|u ]ce%1
human-to-human transmission. The last pandemic struck in 1968 - when ,) u7P Ms
bird flu combined with a human strain and went on to kill 1 million Uo D@ix&0
people worldwide. Uu}a! V
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In May, on Sumatra island in Indonesia, a cluster of eight cases was T?!D?YV
identified, six of whom died. The World Health Organization PF6w'T 5
immediately dispatched a team to investigate. MPS{MGVjbJ
The U.N. agency was concerned enough by the reports to put 0q4E^}iR
pharmaceuticals company Roche Holding AG on standby in case its \R}`S`fIw`
global antiviral stockpile, promised to WHO for any operation to 1kDr;.m%
quash an emerging pandemic, needed to be rushed to Indonesia. /a
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Luckily, the Sumatra cluster was confined to a single family. Though ]CL9N
human-to-human transmission occurred - as it has in a handful of )^D:VY9 2
other cases - the virus did not adapt enough to become easily jdEqa$CX G
infectious. ~ "IjT'W
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This highlighted many of the problems that continue to plague public 0/g 0=dW=
health officials, namely, patchy surveillance systems and limited :t'*fHi ~
virus information. @An "ClDa
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Even in China, where H5N1 has circulated the longest, surveillance oph QdJM
is not ideal. |IgH0
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"Monitoring the 14 billion birds in China, especially when most of ~"t33U6
them are in back yards, is an enormous challenge," said Dr. Henk (: TZ~"VY
Bekedam, WHO's top official in China. Of the 21 human cases China }2 X"
has logged so far, 20 were in areas without reported H5N1 outbreaks >&`S$1 o
in birds. p2\mPFxEP
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"We need to start looking harder for where the virus is hiding," tt%lDr1
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Bekedam said. EAE \'9T&g
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To better understand the virus' activity, it would help to have more tsqkV7?
virus samples from every H5N1-affected country. But public health 2y"|l
authorities are at the mercy of governments and academics. $
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Scientists may hoard viruses while waiting for academic papers to be W
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published first. And developing countries may be wary of sharing \A ?B{*
virus samples if the vaccines that might be developed from them j1sZRl)D
might ultimately be unaffordable. u5LrZ
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That leaves public health officials with an incomplete viral i!U,q
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picture. q7!$-
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"It shouldn't just be WHO as a lonely voice in the desert, calling a 7_ &;
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu bV~z}V&
expert with the Food and Agriculture Organization in Vietnam. All B,f4<
countries, need to understand that sharing will help them better l^ Q -KUI
prepare for a flu pandemic, he said.
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Though scientists are bracing themselves for increased bird flu tzKIi_2
activity in the winter, there are no predictions about where it K< ;I*cA
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might appear next. The WHO's Fukuda said it would not be a surprise |v[0(
to see it appear in new countries.
