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题目:Bird flu and the deteriorating environment as y:[r"
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Earlier this year, bird flu panic was in full swing: The French +R{~%ZTK
feared for their foie gras, the Swiss locked their chickens indoors, _pvt,pW
and Americans enlisted prison inmates in Alaska to help spot qAlX#]
infected wild birds. ^)| tf\4
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The H5N1 virus - previously confined to Southeast Asia - was N693eN!
striking birds in places as diverse as Germany, Egypt, and Nigeria, qM 3(OvCt
and a flu pandemic seemed inevitable. sdd%u~4,X
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Then the virus went quiet. Except for a steady stream of human cases c3<H272\
in Indonesia, the current flu epicenter, the past year's worries ).Iifu|ks
about a catastrophic global outbreak largely disappeared. 8 QI+ O`
What happened? o(D_ /]'8
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Part of the explanation may be seasonal. Bird flu tends to be most 8LuU
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active in the colder months, as the virus survives longer at low *8u<?~9F
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"Many of us are holding our breath to see what happens in the {8%KO1xB
winter," said Dr. Malik Peiris, a microbiology professor at Hong 8`I,KkWg
Kong University. "H5N1 spread very rapidly last year," Peiris said. &,,:pL[
"So the question is, was that a one-off incident?" U:PtRSdn!b
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Some experts suspect poultry vaccination has, paradoxically, wjOJ n]
complicated detection. Vaccination reduces the amount of virus nVP |{M
circulating, but low levels of the virus may still be causing Fd%JF#Hk
outbreaks - without the obvious signs of dying birds. H>-{.E1bG
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"It's now harder to spot what's happening with the flu in animals WK {F
and humans," said Dr. Angus Nicoll, influenza director at the br?pfs$U
European Centres for Disease Control and Prevention. 25W #mh,'
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While the pandemic has not materialized, experts say it's too early JM*!(\Y
to relax. Z:,`hW*A6
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, w,<n5dMv
coordinator of the World Health Organization's global influenza 6_;n bqY&
program. But although the virus could mutate into a pandemic strain, ~*tn|?%
Fukuda points out that it might go the other direction instead, !_iv~Q zv
becoming less dangerous for humans. &hM7y7
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H5N1 has primarily stalked Asia. This year, however, it crossed the *c (YlfeZ#
continental divide, infecting people in Turkey, Iraq, Egypt, *3fhVl=8^*
Djibouti, and Azerbaijan. j:HIcCp
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But despite the deaths of 154 people, and hundreds of millions of [z'jL' \4
birds worldwide dying or being slaughtered, the virus still has not n 3\~H9
learned how to infect humans easily. srS)"Jt
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Flu viruses constantly evolve, so the mere appearance of mutations 7GJcg7s*T
is not enough to raise alarm. The key is to identify which mutations xi)$t#K"
are the most worrisome. ?YF2Uc8z%2
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"We don't really know how many changes this virus has got to make to Ns\};j?TU*
adapt to humans, if it can at all," said Dr. Richard Webby, a bird tLP
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flu expert at St. Jude Children's Research Hospital in Tennessee. 8\+DSA
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The most obvious sign that a pandemic may be under way will almost
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certainly come from the field: a sudden spike in cases suggesting 5eM{>qr}
human-to-human transmission. The last pandemic struck in 1968 - when ]VS:5kOj`
bird flu combined with a human strain and went on to kill 1 million PE?ICou
people worldwide. y-~_ W 6\
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In May, on Sumatra island in Indonesia, a cluster of eight cases was Fx:4d$>;
identified, six of whom died. The World Health Organization Fv:x>qZr@
immediately dispatched a team to investigate. D/wJF[_
The U.N. agency was concerned enough by the reports to put G[{Av5g mx
pharmaceuticals company Roche Holding AG on standby in case its :G &:
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global antiviral stockpile, promised to WHO for any operation to =JxEM7r
quash an emerging pandemic, needed to be rushed to Indonesia. 7t/Y5Qf
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Luckily, the Sumatra cluster was confined to a single family. Though #oN}DP
human-to-human transmission occurred - as it has in a handful of }[(v(1j='~
other cases - the virus did not adapt enough to become easily /L./-92NH4
infectious. o[q|dhrANh
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This highlighted many of the problems that continue to plague public 0IBQ E
health officials, namely, patchy surveillance systems and limited (i1p6
virus information.
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Even in China, where H5N1 has circulated the longest, surveillance l8e)|MSh
is not ideal. n Q{~D5y,,
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"Monitoring the 14 billion birds in China, especially when most of i`?yi-R&
them are in back yards, is an enormous challenge," said Dr. Henk Iz>\qC}
Bekedam, WHO's top official in China. Of the 21 human cases China PH'n`D #
has logged so far, 20 were in areas without reported H5N1 outbreaks RLcC>Z
in birds. ,$RXN8x1
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"We need to start looking harder for where the virus is hiding," 2-@
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Bekedam said. } g: 'K
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To better understand the virus' activity, it would help to have more x'SIHV4M@Q
virus samples from every H5N1-affected country. But public health 5'%O]~
authorities are at the mercy of governments and academics. Dj 6^|R$z&
Scientists may hoard viruses while waiting for academic papers to be ' p F$6
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published first. And developing countries may be wary of sharing jc@=
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virus samples if the vaccines that might be developed from them 'z@]h
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might ultimately be unaffordable. rd "!&i
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That leaves public health officials with an incomplete viral 2
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picture. u LNOhgSUf
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"It shouldn't just be WHO as a lonely voice in the desert, calling dF|R`Pa2ML
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu e-.( O8
expert with the Food and Agriculture Organization in Vietnam. All K7/&~;ZwT
countries, need to understand that sharing will help them better ;Rm';IW$
prepare for a flu pandemic, he said. 8: uh0
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Though scientists are bracing themselves for increased bird flu [g{fz3
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activity in the winter, there are no predictions about where it $XKUw" %
might appear next. The WHO's Fukuda said it would not be a surprise D%=&euB
to see it appear in new countries.
