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题目:Bird flu and the deteriorating environment 1
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Earlier this year, bird flu panic was in full swing: The French Wg5<@=x!G
feared for their foie gras, the Swiss locked their chickens indoors, ?2(5 2?cJ
and Americans enlisted prison inmates in Alaska to help spot )k^y<lC2a
infected wild birds. |l-~,eRvi5
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The H5N1 virus - previously confined to Southeast Asia - was 2RbK##`vC
striking birds in places as diverse as Germany, Egypt, and Nigeria, Rs@>
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and a flu pandemic seemed inevitable. ""f'L,`{.
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Then the virus went quiet. Except for a steady stream of human cases + dG3/vV
in Indonesia, the current flu epicenter, the past year's worries _|Uv7>}J^
about a catastrophic global outbreak largely disappeared. P @Jo[J<
What happened? 0SV<Pl^
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Part of the explanation may be seasonal. Bird flu tends to be most d rQI@sPp
active in the colder months, as the virus survives longer at low Lcz`
temperatures. J))U YJ O
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"Many of us are holding our breath to see what happens in the )61X, z
winter," said Dr. Malik Peiris, a microbiology professor at Hong ^~1Z"kAnT
Kong University. "H5N1 spread very rapidly last year," Peiris said. 7>V*gV?v
"So the question is, was that a one-off incident?" p:;
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Some experts suspect poultry vaccination has, paradoxically, b5S4C2Ynq
complicated detection. Vaccination reduces the amount of virus ffQm"s:P
circulating, but low levels of the virus may still be causing $DlO<
outbreaks - without the obvious signs of dying birds. `F$lO2 #k
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"It's now harder to spot what's happening with the flu in animals ES\=M O5a7
and humans," said Dr. Angus Nicoll, influenza director at the @R_ON"h
European Centres for Disease Control and Prevention. +a" f)4\
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While the pandemic has not materialized, experts say it's too early 7NRm\%^q
to relax.
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, R2A#2{+H
coordinator of the World Health Organization's global influenza {TZV^gT4
program. But although the virus could mutate into a pandemic strain, s o7.
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Fukuda points out that it might go the other direction instead,
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becoming less dangerous for humans. ffMk.SqI
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H5N1 has primarily stalked Asia. This year, however, it crossed the NX5 $x/uz
continental divide, infecting people in Turkey, Iraq, Egypt, IgN^~ag`
Djibouti, and Azerbaijan. H*P[t yz$
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But despite the deaths of 154 people, and hundreds of millions of i<(~J4} b
birds worldwide dying or being slaughtered, the virus still has not c#f @v45
learned how to infect humans easily. CQPq5/@Y4
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Flu viruses constantly evolve, so the mere appearance of mutations <U c
is not enough to raise alarm. The key is to identify which mutations qLPuKIF
are the most worrisome. z+{xW7
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"We don't really know how many changes this virus has got to make to
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adapt to humans, if it can at all," said Dr. Richard Webby, a bird s\< @v7A
flu expert at St. Jude Children's Research Hospital in Tennessee. \XO'7bNu-
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The most obvious sign that a pandemic may be under way will almost MxH |yo[
certainly come from the field: a sudden spike in cases suggesting 0cDP:EzR;
human-to-human transmission. The last pandemic struck in 1968 - when 8rjD1<
bird flu combined with a human strain and went on to kill 1 million U^eos;:s8
people worldwide. ,"F0#5
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In May, on Sumatra island in Indonesia, a cluster of eight cases was G{{M' 1
identified, six of whom died. The World Health Organization p I~;3T:!
immediately dispatched a team to investigate. J"Fp),
The U.N. agency was concerned enough by the reports to put >_\[C?8
pharmaceuticals company Roche Holding AG on standby in case its MMUlA $*t
global antiviral stockpile, promised to WHO for any operation to nW}
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quash an emerging pandemic, needed to be rushed to Indonesia. pTB 7k3g
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Luckily, the Sumatra cluster was confined to a single family. Though $ 4}G
human-to-human transmission occurred - as it has in a handful of cR
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other cases - the virus did not adapt enough to become easily yn"4qC#Z
infectious. ksCF"o /@V
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This highlighted many of the problems that continue to plague public 74a@/'WbE
health officials, namely, patchy surveillance systems and limited 2Y<]X7Ch:
virus information. oH!O {pQK}
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Even in China, where H5N1 has circulated the longest, surveillance GKjtX?~1
is not ideal. aL`wz !
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"Monitoring the 14 billion birds in China, especially when most of I{r*Y9
them are in back yards, is an enormous challenge," said Dr. Henk ZHa>8x;Mjl
Bekedam, WHO's top official in China. Of the 21 human cases China M0~%[nX
has logged so far, 20 were in areas without reported H5N1 outbreaks &oq 0XV.M^
in birds. q 5L^>"
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"We need to start looking harder for where the virus is hiding," wpN3-D
Bekedam said. _ilitwRN3
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To better understand the virus' activity, it would help to have more `}KxzD
virus samples from every H5N1-affected country. But public health '" \'<>Be
authorities are at the mercy of governments and academics. 11YJ W-V
Scientists may hoard viruses while waiting for academic papers to be [U 8/nT
published first. And developing countries may be wary of sharing \~ z$'3H`
virus samples if the vaccines that might be developed from them _@!vF,Wcf
might ultimately be unaffordable. Su"Z3gm5Kw
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That leaves public health officials with an incomplete viral \20} /&
picture. A8{ xZsH
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"It shouldn't just be WHO as a lonely voice in the desert, calling %" 7UYLX
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu )!\6 " {
expert with the Food and Agriculture Organization in Vietnam. All v-d"dC`
countries, need to understand that sharing will help them better 3
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prepare for a flu pandemic, he said. _^#eO`4"
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Though scientists are bracing themselves for increased bird flu 1xd 6p
activity in the winter, there are no predictions about where it 1x;@ BV
might appear next. The WHO's Fukuda said it would not be a surprise EI6kBRMo
to see it appear in new countries.
