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题目:Bird flu and the deteriorating environment ^7:UC\_
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Earlier this year, bird flu panic was in full swing: The French vZqW,GDfXo
feared for their foie gras, the Swiss locked their chickens indoors, :pvVm>
and Americans enlisted prison inmates in Alaska to help spot gla'urb[i|
infected wild birds. G}dq
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The H5N1 virus - previously confined to Southeast Asia - was (
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striking birds in places as diverse as Germany, Egypt, and Nigeria, -_
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and a flu pandemic seemed inevitable. {yxLL-5c
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Then the virus went quiet. Except for a steady stream of human cases kFfNDM#D
in Indonesia, the current flu epicenter, the past year's worries x_(K%0+Ca
about a catastrophic global outbreak largely disappeared. ?'tFTh
What happened? vXak5iq>X
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Part of the explanation may be seasonal. Bird flu tends to be most _Q b ].~
active in the colder months, as the virus survives longer at low ZV-Y q !|t
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"Many of us are holding our breath to see what happens in the {JfL7%
winter," said Dr. Malik Peiris, a microbiology professor at Hong YTfi g{a
Kong University. "H5N1 spread very rapidly last year," Peiris said. *M$$%G(4
"So the question is, was that a one-off incident?" 9SU/ 86|N
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Some experts suspect poultry vaccination has, paradoxically, 3Z}KRsp3
complicated detection. Vaccination reduces the amount of virus _|CO nm
circulating, but low levels of the virus may still be causing Ou|kb61zg
outbreaks - without the obvious signs of dying birds. r;"Qu
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"It's now harder to spot what's happening with the flu in animals h~Z:YY)4
and humans," said Dr. Angus Nicoll, influenza director at the fV!~SX6S
European Centres for Disease Control and Prevention. QghL=
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While the pandemic has not materialized, experts say it's too early * YLp C^&
to relax. "~08<+
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, '*K%\]
coordinator of the World Health Organization's global influenza @3?dI@i(
program. But although the virus could mutate into a pandemic strain,
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Fukuda points out that it might go the other direction instead, -]:1zU
becoming less dangerous for humans. ]OC?g2&6
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H5N1 has primarily stalked Asia. This year, however, it crossed the <07~EP
continental divide, infecting people in Turkey, Iraq, Egypt, KP
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Djibouti, and Azerbaijan. #\6k_toZ
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But despite the deaths of 154 people, and hundreds of millions of yDi'@Z9R?
birds worldwide dying or being slaughtered, the virus still has not ~01t_Xp qc
learned how to infect humans easily. Ro#O{
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Flu viruses constantly evolve, so the mere appearance of mutations 7fW$jiw
is not enough to raise alarm. The key is to identify which mutations ] q|U0(q9
are the most worrisome. lh;;%@1DM
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"We don't really know how many changes this virus has got to make to ezhK[/E=
adapt to humans, if it can at all," said Dr. Richard Webby, a bird Qt=O iKZ
flu expert at St. Jude Children's Research Hospital in Tennessee. GOX2'N\h^
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The most obvious sign that a pandemic may be under way will almost -D
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certainly come from the field: a sudden spike in cases suggesting S\6.vw!'
human-to-human transmission. The last pandemic struck in 1968 - when )fbYP@9>a
bird flu combined with a human strain and went on to kill 1 million AN+S6 t
people worldwide. vk3C&!M<a
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In May, on Sumatra island in Indonesia, a cluster of eight cases was #$u7:p
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identified, six of whom died. The World Health Organization (q=),3/<pU
immediately dispatched a team to investigate. ^x}k1F3
The U.N. agency was concerned enough by the reports to put # 6 M3BF
pharmaceuticals company Roche Holding AG on standby in case its q) y<\cEO
global antiviral stockpile, promised to WHO for any operation to y2> AbrJ
quash an emerging pandemic, needed to be rushed to Indonesia. gL Wbd~
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Luckily, the Sumatra cluster was confined to a single family. Though GNM+sd y+
human-to-human transmission occurred - as it has in a handful of P u,JR
other cases - the virus did not adapt enough to become easily ?PU7xO;_
infectious. D 8)6yPwE
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This highlighted many of the problems that continue to plague public 70N Lv
health officials, namely, patchy surveillance systems and limited N$P\$
virus information. +s x$%N
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Even in China, where H5N1 has circulated the longest, surveillance r!/<%\S
is not ideal. <!derr-K
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"Monitoring the 14 billion birds in China, especially when most of W]M Fq5.
them are in back yards, is an enormous challenge," said Dr. Henk hWRr#03 0
Bekedam, WHO's top official in China. Of the 21 human cases China oGz5ZDa#
has logged so far, 20 were in areas without reported H5N1 outbreaks .hK:-q,
in birds. vg*~t3{ L
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"We need to start looking harder for where the virus is hiding," X1^ Q1?0
Bekedam said. sv+ 6#
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To better understand the virus' activity, it would help to have more :O]US)VSj
virus samples from every H5N1-affected country. But public health f;obK~b[
authorities are at the mercy of governments and academics. q;QE(}.g
Scientists may hoard viruses while waiting for academic papers to be QNGp+xUHJ9
published first. And developing countries may be wary of sharing 7
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virus samples if the vaccines that might be developed from them u4D rZ-v
might ultimately be unaffordable. ?$ M:
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That leaves public health officials with an incomplete viral YhL^kM@c
picture. -{N P3zy
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"It shouldn't just be WHO as a lonely voice in the desert, calling 5' n$aFqI
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu "&@{f:+
expert with the Food and Agriculture Organization in Vietnam. All =LK f.@]#
countries, need to understand that sharing will help them better T%w5%{dqJ
prepare for a flu pandemic, he said. OOnhT
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Though scientists are bracing themselves for increased bird flu # {@qC2!2/
activity in the winter, there are no predictions about where it z[0tM&pv
might appear next. The WHO's Fukuda said it would not be a surprise $ J!PSF8PL
to see it appear in new countries.
