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题目:Bird flu and the deteriorating environment Sd7jd ?#9'
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Earlier this year, bird flu panic was in full swing: The French ddHl&+G
feared for their foie gras, the Swiss locked their chickens indoors, o[Iu9.zJpy
and Americans enlisted prison inmates in Alaska to help spot ImXYI7PL
infected wild birds. 1%Xh[
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The H5N1 virus - previously confined to Southeast Asia - was [F-R*}&x
striking birds in places as diverse as Germany, Egypt, and Nigeria, wgl <JO
and a flu pandemic seemed inevitable. t G_4>-Y#w
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Then the virus went quiet. Except for a steady stream of human cases &Ok1j0~~
in Indonesia, the current flu epicenter, the past year's worries =?5)M_6)
about a catastrophic global outbreak largely disappeared. O8]e(i
What happened? ,54z9F`
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Part of the explanation may be seasonal. Bird flu tends to be most eL3 _L z
active in the colder months, as the virus survives longer at low H|% J"
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"Many of us are holding our breath to see what happens in the nI:M!j5s`
winter," said Dr. Malik Peiris, a microbiology professor at Hong vJ WBr:`L
Kong University. "H5N1 spread very rapidly last year," Peiris said. /7}pReUj
"So the question is, was that a one-off incident?"
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Some experts suspect poultry vaccination has, paradoxically, .psb# 4
complicated detection. Vaccination reduces the amount of virus Ht[$s4 0P
circulating, but low levels of the virus may still be causing '=dQ$fs
outbreaks - without the obvious signs of dying birds. 2e_ Di(us
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"It's now harder to spot what's happening with the flu in animals $d<NN2
and humans," said Dr. Angus Nicoll, influenza director at the $DHE%IN`
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While the pandemic has not materialized, experts say it's too early A@V$~&JCL5
to relax. {irc0gI
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"We have a visible risk in front of us," said Dr. Keiji Fukuda,
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coordinator of the World Health Organization's global influenza A 8-[EBkK
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, Y 9$jJ1V
becoming less dangerous for humans. \F|)w| v
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H5N1 has primarily stalked Asia. This year, however, it crossed the O AXA<
continental divide, infecting people in Turkey, Iraq, Egypt, ;\K]~
Djibouti, and Azerbaijan. ?I +{S
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But despite the deaths of 154 people, and hundreds of millions of ;@Zuet
birds worldwide dying or being slaughtered, the virus still has not 5]&s Xs
learned how to infect humans easily. {o~TbnC
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Flu viruses constantly evolve, so the mere appearance of mutations $gr>Y 2i
is not enough to raise alarm. The key is to identify which mutations 2M x\D
are the most worrisome. J _rrc;F
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"We don't really know how many changes this virus has got to make to 8&JB_%Gb
adapt to humans, if it can at all," said Dr. Richard Webby, a bird ? ^U? ua6
flu expert at St. Jude Children's Research Hospital in Tennessee. NtM>`5{?
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The most obvious sign that a pandemic may be under way will almost jL-2
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certainly come from the field: a sudden spike in cases suggesting
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human-to-human transmission. The last pandemic struck in 1968 - when t+v %%N_
bird flu combined with a human strain and went on to kill 1 million )Fx]
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people worldwide. 'vNju1sfk
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In May, on Sumatra island in Indonesia, a cluster of eight cases was q8P&r Mwy
identified, six of whom died. The World Health Organization x$q} lJv_
immediately dispatched a team to investigate. \Y!# Y#c
The U.N. agency was concerned enough by the reports to put 0si1:+t-[+
pharmaceuticals company Roche Holding AG on standby in case its *H!BThf
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global antiviral stockpile, promised to WHO for any operation to *QQeK# $s
quash an emerging pandemic, needed to be rushed to Indonesia. uXc;!*
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Luckily, the Sumatra cluster was confined to a single family. Though uE.BB#
human-to-human transmission occurred - as it has in a handful of #
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other cases - the virus did not adapt enough to become easily IL|Q-e}Ol
infectious. 1 !_p
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This highlighted many of the problems that continue to plague public Ry >y
health officials, namely, patchy surveillance systems and limited + ,Krq 3P
virus information. [2-n*a(q
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Even in China, where H5N1 has circulated the longest, surveillance f-
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is not ideal. {.2\}7.c
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"Monitoring the 14 billion birds in China, especially when most of TR3U<:
them are in back yards, is an enormous challenge," said Dr. Henk ":
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Bekedam, WHO's top official in China. Of the 21 human cases China 0Agse)
has logged so far, 20 were in areas without reported H5N1 outbreaks 2]vTedSOl
in birds. 6C2~0b
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"We need to start looking harder for where the virus is hiding," BP9#}{kE
Bekedam said. >$'z4TC\T
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To better understand the virus' activity, it would help to have more &B&8$X
virus samples from every H5N1-affected country. But public health 7(1`,Y
authorities are at the mercy of governments and academics. l
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Scientists may hoard viruses while waiting for academic papers to be Ms|c" ?se
published first. And developing countries may be wary of sharing Bh& pZcm|
virus samples if the vaccines that might be developed from them @?<[ //1
might ultimately be unaffordable. 7}VqXUwabx
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That leaves public health officials with an incomplete viral t}eyfflZ
picture. 6 ]x?2P%
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"It shouldn't just be WHO as a lonely voice in the desert, calling M m$\j*f/
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu &1Ndi<Y^
expert with the Food and Agriculture Organization in Vietnam. All o*H U^
countries, need to understand that sharing will help them better @F 5Af/
prepare for a flu pandemic, he said. j4owo#OB-
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Though scientists are bracing themselves for increased bird flu 5z_d$.CIc
activity in the winter, there are no predictions about where it Z8 v 8@Y
might appear next. The WHO's Fukuda said it would not be a surprise wS}c \!@<,
to see it appear in new countries.
