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题目:Bird flu and the deteriorating environment k/c Q Jz
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Earlier this year, bird flu panic was in full swing: The French N _Yop
feared for their foie gras, the Swiss locked their chickens indoors, v 6Tz7
and Americans enlisted prison inmates in Alaska to help spot Kh}#At^C8e
infected wild birds. "4|D"|w
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The H5N1 virus - previously confined to Southeast Asia - was dFK/
striking birds in places as diverse as Germany, Egypt, and Nigeria, 3
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and a flu pandemic seemed inevitable. )mS
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Then the virus went quiet. Except for a steady stream of human cases i_Ab0vy e
in Indonesia, the current flu epicenter, the past year's worries ):3
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about a catastrophic global outbreak largely disappeared. z`y!C3w<
What happened? *v_+a:
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Part of the explanation may be seasonal. Bird flu tends to be most S2'./!3yv
active in the colder months, as the virus survives longer at low s sUWr=mD
temperatures. '
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"Many of us are holding our breath to see what happens in the |>Qj ]
winter," said Dr. Malik Peiris, a microbiology professor at Hong 3dTz$s/[
Kong University. "H5N1 spread very rapidly last year," Peiris said. DY/xBwIF
"So the question is, was that a one-off incident?" [W;iR_7T5
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Some experts suspect poultry vaccination has, paradoxically, 7j| ^ZuI+
complicated detection. Vaccination reduces the amount of virus %F_)!M;x
circulating, but low levels of the virus may still be causing T{<riJ`O
outbreaks - without the obvious signs of dying birds. V{+'(<SV
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"It's now harder to spot what's happening with the flu in animals +}[M&D
and humans," said Dr. Angus Nicoll, influenza director at the &c>%E%!"
European Centres for Disease Control and Prevention. %/iD@2r
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While the pandemic has not materialized, experts say it's too early /vO8s??
to relax. A: ! _ &
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, AQ+MjS,
coordinator of the World Health Organization's global influenza wr>[Eo@%\
program. But although the virus could mutate into a pandemic strain, cip5 -Z@8
Fukuda points out that it might go the other direction instead, W'lejOiw
becoming less dangerous for humans. 89n\$7Ff9
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H5N1 has primarily stalked Asia. This year, however, it crossed the Hw2 9V //
continental divide, infecting people in Turkey, Iraq, Egypt, V9`
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Djibouti, and Azerbaijan. AwnQ5-IR\
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But despite the deaths of 154 people, and hundreds of millions of }Um,wY[tK
birds worldwide dying or being slaughtered, the virus still has not A; _Zw[
learned how to infect humans easily. cvOCBg38BH
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Flu viruses constantly evolve, so the mere appearance of mutations OTe h8h
is not enough to raise alarm. The key is to identify which mutations nMM:Tr
are the most worrisome. (}B3df
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"We don't really know how many changes this virus has got to make to m3#rU%Wj
adapt to humans, if it can at all," said Dr. Richard Webby, a bird iH a:6
flu expert at St. Jude Children's Research Hospital in Tennessee. !}lCwV
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The most obvious sign that a pandemic may be under way will almost o[^nmHrM2
certainly come from the field: a sudden spike in cases suggesting )&6ZgRq
human-to-human transmission. The last pandemic struck in 1968 - when !
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bird flu combined with a human strain and went on to kill 1 million { k}$L|w
people worldwide. G !)
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In May, on Sumatra island in Indonesia, a cluster of eight cases was K>2M*bGc p
identified, six of whom died. The World Health Organization b^ :frjaE3
immediately dispatched a team to investigate. k3+LP7| *
The U.N. agency was concerned enough by the reports to put v\lKY*@f
pharmaceuticals company Roche Holding AG on standby in case its *qZBq&7tb
global antiviral stockpile, promised to WHO for any operation to [a_ 'pAH
quash an emerging pandemic, needed to be rushed to Indonesia. =4[
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Luckily, the Sumatra cluster was confined to a single family. Though 8kLHQ0pmu
human-to-human transmission occurred - as it has in a handful of V]Rt[l]
other cases - the virus did not adapt enough to become easily kGmz1S}2
infectious. p %R+ c
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This highlighted many of the problems that continue to plague public []jbzVwS2
health officials, namely, patchy surveillance systems and limited Z aYUf
virus information. k4PXH
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Even in China, where H5N1 has circulated the longest, surveillance b
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is not ideal. -TMg9M4
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"Monitoring the 14 billion birds in China, especially when most of O\SH;y,N
them are in back yards, is an enormous challenge," said Dr. Henk @'A0Lq+#
Bekedam, WHO's top official in China. Of the 21 human cases China )Ma/] eZ^I
has logged so far, 20 were in areas without reported H5N1 outbreaks O!il TMr
in birds. ejia4(Cd
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"We need to start looking harder for where the virus is hiding," ik](k"1{
Bekedam said. g[*" LOw
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To better understand the virus' activity, it would help to have more $h}5cl
virus samples from every H5N1-affected country. But public health VsJKxa4
authorities are at the mercy of governments and academics. |e<$
Scientists may hoard viruses while waiting for academic papers to be @?jtB
published first. And developing countries may be wary of sharing .C.b5x!
virus samples if the vaccines that might be developed from them qRR%aJ/
might ultimately be unaffordable. .Cf! 5[0E
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That leaves public health officials with an incomplete viral
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picture. Z- t&AH
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"It shouldn't just be WHO as a lonely voice in the desert, calling 6{{<+
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for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu
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expert with the Food and Agriculture Organization in Vietnam. All UCXRF
countries, need to understand that sharing will help them better Dw.I<fns^B
prepare for a flu pandemic, he said. rW090Py
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Though scientists are bracing themselves for increased bird flu (@qPyM6~}
activity in the winter, there are no predictions about where it GXIzAB(
might appear next. The WHO's Fukuda said it would not be a surprise Alo L+eN@
to see it appear in new countries.
