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题目:Bird flu and the deteriorating environment R]*K:~DM
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Earlier this year, bird flu panic was in full swing: The French WVvv I9
feared for their foie gras, the Swiss locked their chickens indoors, :tv,]05t
and Americans enlisted prison inmates in Alaska to help spot &W6^sj*k5U
infected wild birds. "kgdbAZ
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The H5N1 virus - previously confined to Southeast Asia - was ]- QA'Lq
striking birds in places as diverse as Germany, Egypt, and Nigeria, QGmn#]w\\
and a flu pandemic seemed inevitable. 0b(N^$js'
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Then the virus went quiet. Except for a steady stream of human cases LTx,cP
in Indonesia, the current flu epicenter, the past year's worries `$ aZ0+
about a catastrophic global outbreak largely disappeared. Czu\RXJR
What happened? J!U}iD@occ
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Part of the explanation may be seasonal. Bird flu tends to be most gQ1;],_
active in the colder months, as the virus survives longer at low \&gB)czEO
temperatures. D]Xsvv
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"Many of us are holding our breath to see what happens in the >]5P
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winter," said Dr. Malik Peiris, a microbiology professor at Hong Sa;qW3dt3E
Kong University. "H5N1 spread very rapidly last year," Peiris said. OMg<V
"So the question is, was that a one-off incident?" ]^K 4i)\
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Some experts suspect poultry vaccination has, paradoxically, yFlm[K5YD
complicated detection. Vaccination reduces the amount of virus /,Re "!jh
circulating, but low levels of the virus may still be causing Bad:n o\W
outbreaks - without the obvious signs of dying birds. b |p)9&^r
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"It's now harder to spot what's happening with the flu in animals * U=s\
and humans," said Dr. Angus Nicoll, influenza director at the ocS5SB]8
European Centres for Disease Control and Prevention. &t:Gx<]
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While the pandemic has not materialized, experts say it's too early eu|;eP-+d
to relax. +8Ymw:D7a
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, vbe|hO""
coordinator of the World Health Organization's global influenza {vyv7L
program. But although the virus could mutate into a pandemic strain, z]`k#O%%)
Fukuda points out that it might go the other direction instead, Pax|x15
becoming less dangerous for humans. TOXfWEU3>
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H5N1 has primarily stalked Asia. This year, however, it crossed the J!pygn
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continental divide, infecting people in Turkey, Iraq, Egypt, ]B3=lc "
Djibouti, and Azerbaijan. T@&K- UQ
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But despite the deaths of 154 people, and hundreds of millions of -0{r>,&Mm
birds worldwide dying or being slaughtered, the virus still has not aYS!xh206
learned how to infect humans easily. v)t:|Q{I
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Flu viruses constantly evolve, so the mere appearance of mutations m\r@@!
is not enough to raise alarm. The key is to identify which mutations J1sv[$ 9
are the most worrisome. +&( M
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"We don't really know how many changes this virus has got to make to 6NM:DI\%
adapt to humans, if it can at all," said Dr. Richard Webby, a bird q?DTMK x
flu expert at St. Jude Children's Research Hospital in Tennessee. vK\%%H
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The most obvious sign that a pandemic may be under way will almost dDGgvi|[Mz
certainly come from the field: a sudden spike in cases suggesting 9c#+qH
human-to-human transmission. The last pandemic struck in 1968 - when W;L7SF g )
bird flu combined with a human strain and went on to kill 1 million F{Jw ^\
people worldwide. dx &'fe*?
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In May, on Sumatra island in Indonesia, a cluster of eight cases was w?wG(+X7
identified, six of whom died. The World Health Organization SmdjyK1~8
immediately dispatched a team to investigate. dzsmIV+
The U.N. agency was concerned enough by the reports to put D!NQ~'.a=2
pharmaceuticals company Roche Holding AG on standby in case its 6[LM_eP
global antiviral stockpile, promised to WHO for any operation to NI#:|}CYS
quash an emerging pandemic, needed to be rushed to Indonesia. =Ja] T~0A
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Luckily, the Sumatra cluster was confined to a single family. Though f3&[#%
human-to-human transmission occurred - as it has in a handful of iH@yCNE"
other cases - the virus did not adapt enough to become easily !?p%xj?
infectious. LuSLkLN
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This highlighted many of the problems that continue to plague public 2FF4W54 I
health officials, namely, patchy surveillance systems and limited <2|O:G
virus information. ;04Ldb1{|3
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Even in China, where H5N1 has circulated the longest, surveillance pUq1| )g
is not ideal. sz
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"Monitoring the 14 billion birds in China, especially when most of /VzI'^
them are in back yards, is an enormous challenge," said Dr. Henk j!4et;
Bekedam, WHO's top official in China. Of the 21 human cases China 2viM)+
has logged so far, 20 were in areas without reported H5N1 outbreaks n\5RAIg
in birds. bQP {|
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"We need to start looking harder for where the virus is hiding," h0-hT
Bekedam said. Z@&D ki
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To better understand the virus' activity, it would help to have more oiyzHx
virus samples from every H5N1-affected country. But public health 2 fS[J'-o
authorities are at the mercy of governments and academics. N:tY":Hi
Scientists may hoard viruses while waiting for academic papers to be %]6~Eq%s
published first. And developing countries may be wary of sharing D3^7y.u<)
virus samples if the vaccines that might be developed from them Q7C ;1aO
might ultimately be unaffordable. +|@rD/I6
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That leaves public health officials with an incomplete viral S h,&{z!
picture. C2xL1`
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"It shouldn't just be WHO as a lonely voice in the desert, calling HXYRH
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu 3g~^[&|i
expert with the Food and Agriculture Organization in Vietnam. All mBJe qG
countries, need to understand that sharing will help them better {^rs #, W
prepare for a flu pandemic, he said. D?,#aB"
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Though scientists are bracing themselves for increased bird flu @81Vc<dJ
activity in the winter, there are no predictions about where it #gaQaUjR
might appear next. The WHO's Fukuda said it would not be a surprise {}m PE d b
to see it appear in new countries.
