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题目:Bird flu and the deteriorating environment +]
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Earlier this year, bird flu panic was in full swing: The French LgaJp_d>9*
feared for their foie gras, the Swiss locked their chickens indoors, qq/Cn4f N8
and Americans enlisted prison inmates in Alaska to help spot s. ~SV"
infected wild birds. NUU}8a(K
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The H5N1 virus - previously confined to Southeast Asia - was lC2xl( #!
striking birds in places as diverse as Germany, Egypt, and Nigeria, OlK2<
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and a flu pandemic seemed inevitable. 2.[qcs3zl
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Then the virus went quiet. Except for a steady stream of human cases "~
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in Indonesia, the current flu epicenter, the past year's worries _
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about a catastrophic global outbreak largely disappeared. =_86{ wl k
What happened? 5Q88OxH
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Part of the explanation may be seasonal. Bird flu tends to be most N3?d?+A$
active in the colder months, as the virus survives longer at low v Zxy9Wmc
temperatures. cBA[ D~s
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"Many of us are holding our breath to see what happens in the 7[)(;-
winter," said Dr. Malik Peiris, a microbiology professor at Hong DkI
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Kong University. "H5N1 spread very rapidly last year," Peiris said. r3kI'I|bq
"So the question is, was that a one-off incident?" 6i4j(P
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Some experts suspect poultry vaccination has, paradoxically, )\(pDn$W
complicated detection. Vaccination reduces the amount of virus twn@~$
circulating, but low levels of the virus may still be causing 9Dl \S F[
outbreaks - without the obvious signs of dying birds. QKO(8D 6+
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"It's now harder to spot what's happening with the flu in animals cG?266{g
and humans," said Dr. Angus Nicoll, influenza director at the 6yb<4 @LOb
European Centres for Disease Control and Prevention. !S:@x.n@iR
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While the pandemic has not materialized, experts say it's too early ^wlep1D
to relax. a|NU)mgEI
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, d1-p];&
coordinator of the World Health Organization's global influenza | QA8"&r
program. But although the virus could mutate into a pandemic strain, ?KN_J
Fukuda points out that it might go the other direction instead, zYL^e @
becoming less dangerous for humans. `Nn?G
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H5N1 has primarily stalked Asia. This year, however, it crossed the U ~m.I
continental divide, infecting people in Turkey, Iraq, Egypt, =S,<yQJ
Djibouti, and Azerbaijan. EMG*8HRI>r
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But despite the deaths of 154 people, and hundreds of millions of \Hd B
birds worldwide dying or being slaughtered, the virus still has not Vd4osBu{fY
learned how to infect humans easily. ;[9Is\
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Flu viruses constantly evolve, so the mere appearance of mutations mQd?Tyvn
is not enough to raise alarm. The key is to identify which mutations _=5ZB_I
are the most worrisome. SO/]d70HG
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"We don't really know how many changes this virus has got to make to Z&,}Fgl!F
adapt to humans, if it can at all," said Dr. Richard Webby, a bird [2V/v
flu expert at St. Jude Children's Research Hospital in Tennessee. b`zf&Mn
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The most obvious sign that a pandemic may be under way will almost #9 OP.4
certainly come from the field: a sudden spike in cases suggesting m12 B :f
human-to-human transmission. The last pandemic struck in 1968 - when |U
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bird flu combined with a human strain and went on to kill 1 million `x)bw
people worldwide.
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In May, on Sumatra island in Indonesia, a cluster of eight cases was ;4$C$ r!t
identified, six of whom died. The World Health Organization Bq_P?Q+\
immediately dispatched a team to investigate. i&)C,
The U.N. agency was concerned enough by the reports to put R"`{E,yj
pharmaceuticals company Roche Holding AG on standby in case its om?CF l
global antiviral stockpile, promised to WHO for any operation to 0z7mre^Q
quash an emerging pandemic, needed to be rushed to Indonesia. <z 2mNq
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Luckily, the Sumatra cluster was confined to a single family. Though WG} CPkj
human-to-human transmission occurred - as it has in a handful of E^a `IA
other cases - the virus did not adapt enough to become easily CL : M>(
infectious. H^;S}<pxW
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This highlighted many of the problems that continue to plague public &xroms"S=
health officials, namely, patchy surveillance systems and limited Ks2%F&\cE
virus information. E :=KH\2f
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Even in China, where H5N1 has circulated the longest, surveillance h!a v)nhM
is not ideal. Ej09RO"pB
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"Monitoring the 14 billion birds in China, especially when most of fhIj+/{_O
them are in back yards, is an enormous challenge," said Dr. Henk $1zeY6 O
Bekedam, WHO's top official in China. Of the 21 human cases China m
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has logged so far, 20 were in areas without reported H5N1 outbreaks oEoJa:h
in birds. w <>6>w@GZ
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"We need to start looking harder for where the virus is hiding," Po11EZa$a
Bekedam said. 7h9[-d6
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To better understand the virus' activity, it would help to have more %_R| @cyD
virus samples from every H5N1-affected country. But public health 3p
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authorities are at the mercy of governments and academics. yb{{ z @
Scientists may hoard viruses while waiting for academic papers to be k-cIb@+"
published first. And developing countries may be wary of sharing x$?7)F&z
virus samples if the vaccines that might be developed from them G q:4rG|
might ultimately be unaffordable. ]RX tC*
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That leaves public health officials with an incomplete viral ? WQ
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picture. i=X*
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"It shouldn't just be WHO as a lonely voice in the desert, calling r5!x,{E6
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu SXo[[ao
expert with the Food and Agriculture Organization in Vietnam. All c."bTq4tJ
countries, need to understand that sharing will help them better Pm#x?1rAj
prepare for a flu pandemic, he said. AJ?}Hel[0
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Though scientists are bracing themselves for increased bird flu Ld}(*-1i
activity in the winter, there are no predictions about where it j*H;a ? Y
might appear next. The WHO's Fukuda said it would not be a surprise BsK|:MM]
to see it appear in new countries.
