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题目:Bird flu and the deteriorating environment 048kP Xm`
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Earlier this year, bird flu panic was in full swing: The French -F>jIgeC2v
feared for their foie gras, the Swiss locked their chickens indoors, : @&/kyGH
and Americans enlisted prison inmates in Alaska to help spot dqAw5[qMJ
infected wild birds. -{A<.a3P}=
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The H5N1 virus - previously confined to Southeast Asia - was C7?/%7{
striking birds in places as diverse as Germany, Egypt, and Nigeria, O
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and a flu pandemic seemed inevitable. mV m Gg
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Then the virus went quiet. Except for a steady stream of human cases B1Oq!k
in Indonesia, the current flu epicenter, the past year's worries BORA(,
about a catastrophic global outbreak largely disappeared. {: W$LWET
What happened? M: V_/@W.
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Part of the explanation may be seasonal. Bird flu tends to be most )CyS#j#=
active in the colder months, as the virus survives longer at low J-4:H
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"Many of us are holding our breath to see what happens in the 9C i-v/M]
winter," said Dr. Malik Peiris, a microbiology professor at Hong \C1nZk?3
Kong University. "H5N1 spread very rapidly last year," Peiris said. k+4#!.HX^
"So the question is, was that a one-off incident?" kNL\m[W8$
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Some experts suspect poultry vaccination has, paradoxically, . [ mR M
complicated detection. Vaccination reduces the amount of virus X 8`Sf>
circulating, but low levels of the virus may still be causing ?' je)F
outbreaks - without the obvious signs of dying birds. 3k?X-|O8AZ
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"It's now harder to spot what's happening with the flu in animals K4);HJ|=
and humans," said Dr. Angus Nicoll, influenza director at the c0fo7|
European Centres for Disease Control and Prevention. 8sCv]|cn
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While the pandemic has not materialized, experts say it's too early b_):MQ1{
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, < d_!mKw
coordinator of the World Health Organization's global influenza $tS}LN_!
program. But although the virus could mutate into a pandemic strain, !? gKqx'T$
Fukuda points out that it might go the other direction instead, 1'\/,Es
becoming less dangerous for humans. of v)SCjd
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H5N1 has primarily stalked Asia. This year, however, it crossed the O0y_Lm\
continental divide, infecting people in Turkey, Iraq, Egypt, 0K2`-mL
Djibouti, and Azerbaijan. xZv# Es%#
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But despite the deaths of 154 people, and hundreds of millions of #lW`{i
birds worldwide dying or being slaughtered, the virus still has not ^v`\x5"Vp
learned how to infect humans easily. uR r o?m<
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Flu viruses constantly evolve, so the mere appearance of mutations N* &1GT#9
is not enough to raise alarm. The key is to identify which mutations 9
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are the most worrisome. %1$,Vs<RH
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"We don't really know how many changes this virus has got to make to .h4 \Y A
adapt to humans, if it can at all," said Dr. Richard Webby, a bird KMjhZap
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flu expert at St. Jude Children's Research Hospital in Tennessee. <yFu*(Q
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The most obvious sign that a pandemic may be under way will almost -p XSSa;O9
certainly come from the field: a sudden spike in cases suggesting .UY^oR=b{
human-to-human transmission. The last pandemic struck in 1968 - when < ? 4V
bird flu combined with a human strain and went on to kill 1 million [^98fAlz6
people worldwide. o$l
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In May, on Sumatra island in Indonesia, a cluster of eight cases was K}MK<2vU
identified, six of whom died. The World Health Organization 1F&Trqq
immediately dispatched a team to investigate. 76h ,]xi
The U.N. agency was concerned enough by the reports to put >_"an~Ss
pharmaceuticals company Roche Holding AG on standby in case its D!-g&HBTC
global antiviral stockpile, promised to WHO for any operation to T !WT;A
quash an emerging pandemic, needed to be rushed to Indonesia. XXn67sF/
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Luckily, the Sumatra cluster was confined to a single family. Though 'XP7"
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human-to-human transmission occurred - as it has in a handful of 7/@TF/V
other cases - the virus did not adapt enough to become easily GqaCj^2f
infectious. =QiI :|eRA
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This highlighted many of the problems that continue to plague public 9u}Hmb
health officials, namely, patchy surveillance systems and limited hxd`OG<gF
virus information. EF }\brD1
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Even in China, where H5N1 has circulated the longest, surveillance YdC6k? tzS
is not ideal. -g Sa_8R
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"Monitoring the 14 billion birds in China, especially when most of V0.vQ/
them are in back yards, is an enormous challenge," said Dr. Henk Pz |>
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Bekedam, WHO's top official in China. Of the 21 human cases China cyv`B3}
has logged so far, 20 were in areas without reported H5N1 outbreaks 1&evG-#<:
in birds. j9 4=hJVKi
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"We need to start looking harder for where the virus is hiding," a85$K$b>
Bekedam said. #crQ1p) \
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To better understand the virus' activity, it would help to have more JG!m c7
virus samples from every H5N1-affected country. But public health i6tf2oqO7
authorities are at the mercy of governments and academics. kmsb hYM)
Scientists may hoard viruses while waiting for academic papers to be NI}yVV
published first. And developing countries may be wary of sharing )72+\C[*~r
virus samples if the vaccines that might be developed from them >:S?Mnv6
might ultimately be unaffordable. z Rl3KjET
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That leaves public health officials with an incomplete viral ox>^>wR*
picture.
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"It shouldn't just be WHO as a lonely voice in the desert, calling Lh"<XYY
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu 3n1;G8Nf
expert with the Food and Agriculture Organization in Vietnam. All ^ f
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countries, need to understand that sharing will help them better ARVf[BAJ-*
prepare for a flu pandemic, he said. /k6MzFoid
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Though scientists are bracing themselves for increased bird flu Ovt.!8
activity in the winter, there are no predictions about where it ygS;$2m%2
might appear next. The WHO's Fukuda said it would not be a surprise dA`IEQJL
to see it appear in new countries.
