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题目:Bird flu and the deteriorating environment 52RFB!Z[
范文 l IdY\_@$ v
Earlier this year, bird flu panic was in full swing: The French R9dC$Y]\M
feared for their foie gras, the Swiss locked their chickens indoors, Px qRb
and Americans enlisted prison inmates in Alaska to help spot | .8lS3C
infected wild birds. fi/[(RBG
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The H5N1 virus - previously confined to Southeast Asia - was \&|zD"*
striking birds in places as diverse as Germany, Egypt, and Nigeria, yP&SA+
and a flu pandemic seemed inevitable. >
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Then the virus went quiet. Except for a steady stream of human cases |l*# pN&L
in Indonesia, the current flu epicenter, the past year's worries n Wrkn m
about a catastrophic global outbreak largely disappeared. Wa/&H$d\u@
What happened? +`@)87O
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Part of the explanation may be seasonal. Bird flu tends to be most gEejLyOag
active in the colder months, as the virus survives longer at low Pk9 4O
temperatures. 6b-j
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"Many of us are holding our breath to see what happens in the #
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winter," said Dr. Malik Peiris, a microbiology professor at Hong x B%Felz
Kong University. "H5N1 spread very rapidly last year," Peiris said. #i#4h< R
"So the question is, was that a one-off incident?" h4j{44MT
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Some experts suspect poultry vaccination has, paradoxically, {"c S:u
complicated detection. Vaccination reduces the amount of virus Jgf73IX[
circulating, but low levels of the virus may still be causing ,]OL[m
outbreaks - without the obvious signs of dying birds. t-xw= &!w
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"It's now harder to spot what's happening with the flu in animals %&c+} m
and humans," said Dr. Angus Nicoll, influenza director at the ) o)k~6uT
European Centres for Disease Control and Prevention. )czuJ5
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While the pandemic has not materialized, experts say it's too early ;P` z
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to relax. mN_KAl n
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, |.A#
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coordinator of the World Health Organization's global influenza B( ]=I@L=W
program. But although the virus could mutate into a pandemic strain, [")3c)OH|
Fukuda points out that it might go the other direction instead, wnf'-dw]
becoming less dangerous for humans. P= e3f(M2
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H5N1 has primarily stalked Asia. This year, however, it crossed the *x^W`i
continental divide, infecting people in Turkey, Iraq, Egypt, 7XE |5G
Djibouti, and Azerbaijan. g~5$X{
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But despite the deaths of 154 people, and hundreds of millions of GqFDN],Wp
birds worldwide dying or being slaughtered, the virus still has not a$ f$CjQ
learned how to infect humans easily. R %QgOz3`
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Flu viruses constantly evolve, so the mere appearance of mutations ;\N{z6
is not enough to raise alarm. The key is to identify which mutations W'Wr8~{h
are the most worrisome. 5ua`5Hb;
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"We don't really know how many changes this virus has got to make to S#IlWU
adapt to humans, if it can at all," said Dr. Richard Webby, a bird z(sfX}%
flu expert at St. Jude Children's Research Hospital in Tennessee. alQMPQVin
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The most obvious sign that a pandemic may be under way will almost c/fU0 cA@
certainly come from the field: a sudden spike in cases suggesting 0w'%10"&U+
human-to-human transmission. The last pandemic struck in 1968 - when w8!S;~x KI
bird flu combined with a human strain and went on to kill 1 million D4e*Wwk
people worldwide. 0Pi D<*EA
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In May, on Sumatra island in Indonesia, a cluster of eight cases was ZT* RD2,
identified, six of whom died. The World Health Organization m+y5Q&;f
immediately dispatched a team to investigate. oPSucz&s
The U.N. agency was concerned enough by the reports to put #t.)4$
pharmaceuticals company Roche Holding AG on standby in case its 7(RtPL pZ
global antiviral stockpile, promised to WHO for any operation to El
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quash an emerging pandemic, needed to be rushed to Indonesia. Up:<NHJT
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Luckily, the Sumatra cluster was confined to a single family. Though qmNg Ez%
human-to-human transmission occurred - as it has in a handful of [)K? e!c8
other cases - the virus did not adapt enough to become easily x|>N
infectious. ZE+VLV v
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This highlighted many of the problems that continue to plague public r_8[}|7;
health officials, namely, patchy surveillance systems and limited T(Q(7
virus information. gP&G63^
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Even in China, where H5N1 has circulated the longest, surveillance >ZAb9=/M)F
is not ideal. [1OX: O|
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"Monitoring the 14 billion birds in China, especially when most of 2vb {PQ
them are in back yards, is an enormous challenge," said Dr. Henk qa>Z?/w
Bekedam, WHO's top official in China. Of the 21 human cases China r&$r=f<
has logged so far, 20 were in areas without reported H5N1 outbreaks *{_WM}G
in birds. ]+C;C
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"We need to start looking harder for where the virus is hiding," X\\c=[#8-
Bekedam said. 28/At
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To better understand the virus' activity, it would help to have more Bo )N<S_=^
virus samples from every H5N1-affected country. But public health Z@Tb3N/[
authorities are at the mercy of governments and academics. _'CYS3-P3
Scientists may hoard viruses while waiting for academic papers to be Ptj,9bf<\
published first. And developing countries may be wary of sharing &:]ej6 V'[
virus samples if the vaccines that might be developed from them WT lR>|Zdn
might ultimately be unaffordable. !YM;5vte+
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That leaves public health officials with an incomplete viral #b^x! lR
picture.
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"It shouldn't just be WHO as a lonely voice in the desert, calling 0$saDmED
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu <KBzZ
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expert with the Food and Agriculture Organization in Vietnam. All |._9;T-Yde
countries, need to understand that sharing will help them better MfJs?N0
prepare for a flu pandemic, he said. 8 !{;yz
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Though scientists are bracing themselves for increased bird flu CrTGC%w{=
activity in the winter, there are no predictions about where it bVLuv`A/
might appear next. The WHO's Fukuda said it would not be a surprise 'N7 AVj
to see it appear in new countries.
