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题目:Bird flu and the deteriorating environment tklU
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Earlier this year, bird flu panic was in full swing: The French r&"}zyL
feared for their foie gras, the Swiss locked their chickens indoors, +3vK=d_Va
and Americans enlisted prison inmates in Alaska to help spot '9GHmtdO,
infected wild birds. ,*0>CBJvv
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The H5N1 virus - previously confined to Southeast Asia - was :<%K6?'@^
striking birds in places as diverse as Germany, Egypt, and Nigeria, \~xsBPX+x
and a flu pandemic seemed inevitable. Z !6\KV]
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Then the virus went quiet. Except for a steady stream of human cases !' ajpK
in Indonesia, the current flu epicenter, the past year's worries MLmc]nL=
about a catastrophic global outbreak largely disappeared. ".v9#|
What happened? M#} )
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Part of the explanation may be seasonal. Bird flu tends to be most Gyy:. ]>&
active in the colder months, as the virus survives longer at low s;}';#
temperatures. e @p` -;<
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"Many of us are holding our breath to see what happens in the s\o
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winter," said Dr. Malik Peiris, a microbiology professor at Hong Qo?"hgjlqm
Kong University. "H5N1 spread very rapidly last year," Peiris said. Pc? d@tm
"So the question is, was that a one-off incident?" (5-"5<-@R
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Some experts suspect poultry vaccination has, paradoxically, n 5S$Dl
complicated detection. Vaccination reduces the amount of virus ErB6fl
circulating, but low levels of the virus may still be causing +ls *0 4
outbreaks - without the obvious signs of dying birds. D8`,PXtV
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"It's now harder to spot what's happening with the flu in animals Z i7(lG
and humans," said Dr. Angus Nicoll, influenza director at the ,2H5CFX/
European Centres for Disease Control and Prevention. <6p{eGAQV
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While the pandemic has not materialized, experts say it's too early E'[pNU*"x-
to relax. }}grJh>tGg
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, X,O& X
coordinator of the World Health Organization's global influenza w' M0Rd]
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, [p4a\ Qg0
becoming less dangerous for humans. *i5&x /ds
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H5N1 has primarily stalked Asia. This year, however, it crossed the e
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continental divide, infecting people in Turkey, Iraq, Egypt, ;1{S"UY
Djibouti, and Azerbaijan.
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But despite the deaths of 154 people, and hundreds of millions of Ks7s2 vK^
birds worldwide dying or being slaughtered, the virus still has not +/Y )s5@<
learned how to infect humans easily. 8l!S<RA
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Flu viruses constantly evolve, so the mere appearance of mutations A. WJ#1i}E
is not enough to raise alarm. The key is to identify which mutations @gxO%@ @
are the most worrisome. i>)Whr'e8
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"We don't really know how many changes this virus has got to make to i7 p#%2
adapt to humans, if it can at all," said Dr. Richard Webby, a bird P.;B
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flu expert at St. Jude Children's Research Hospital in Tennessee. BvX!n"QIb
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The most obvious sign that a pandemic may be under way will almost ;PS [ VdV
certainly come from the field: a sudden spike in cases suggesting uu#ALB
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human-to-human transmission. The last pandemic struck in 1968 - when 7!MW`L/`
bird flu combined with a human strain and went on to kill 1 million 00b
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people worldwide. ( ''`Ce
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In May, on Sumatra island in Indonesia, a cluster of eight cases was EWqKd/
identified, six of whom died. The World Health Organization I9>1WT<Yy
immediately dispatched a team to investigate. Y=}b/[s6;
The U.N. agency was concerned enough by the reports to put /5yW vra
pharmaceuticals company Roche Holding AG on standby in case its M6 0(yTm
global antiviral stockpile, promised to WHO for any operation to 7sLs+ |<"
quash an emerging pandemic, needed to be rushed to Indonesia. o"UqI
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Luckily, the Sumatra cluster was confined to a single family. Though 7J>n;8{%?
human-to-human transmission occurred - as it has in a handful of 1YM04*H
other cases - the virus did not adapt enough to become easily /ebYk-c
infectious. u.!Pda
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This highlighted many of the problems that continue to plague public .` ,YUr$.
health officials, namely, patchy surveillance systems and limited Q*KEODR8\
virus information. >nl *aN
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Even in China, where H5N1 has circulated the longest, surveillance pQEHWq"Q
is not ideal. @+xkd(RfN
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"Monitoring the 14 billion birds in China, especially when most of LClPAbr
them are in back yards, is an enormous challenge," said Dr. Henk Xb;CY9 &
Bekedam, WHO's top official in China. Of the 21 human cases China /{qr~7k,oQ
has logged so far, 20 were in areas without reported H5N1 outbreaks JLg_oK6
in birds. tk,
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"We need to start looking harder for where the virus is hiding," Ye1P5+W(
Bekedam said. $9ON 3>
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To better understand the virus' activity, it would help to have more R8HA X
virus samples from every H5N1-affected country. But public health +F67g00 T|
authorities are at the mercy of governments and academics. v3aiX
Scientists may hoard viruses while waiting for academic papers to be `CHgTkv
published first. And developing countries may be wary of sharing x28B z*O
virus samples if the vaccines that might be developed from them 9prG@
might ultimately be unaffordable. o*dhks[
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That leaves public health officials with an incomplete viral 78NAcP~6c
picture. TJO|{Lxm
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"It shouldn't just be WHO as a lonely voice in the desert, calling !TG"AW
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu ZY][LU~l8
expert with the Food and Agriculture Organization in Vietnam. All w|$;$a7)
countries, need to understand that sharing will help them better {`1zVT p[<
prepare for a flu pandemic, he said. lUWjm%|
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Though scientists are bracing themselves for increased bird flu Ie+z"&0
activity in the winter, there are no predictions about where it bg 7b!t
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might appear next. The WHO's Fukuda said it would not be a surprise Xv'64Nc!;
to see it appear in new countries.
