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题目:Bird flu and the deteriorating environment !I91kJt7
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Earlier this year, bird flu panic was in full swing: The French l%yQ{loTh
feared for their foie gras, the Swiss locked their chickens indoors, 5 pHv5e
and Americans enlisted prison inmates in Alaska to help spot j``Ku@/x0
infected wild birds. u
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The H5N1 virus - previously confined to Southeast Asia - was k%s,(2)30
striking birds in places as diverse as Germany, Egypt, and Nigeria, ;~`/rh
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and a flu pandemic seemed inevitable. /WX&UAG
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Then the virus went quiet. Except for a steady stream of human cases 3 "Qg"\
in Indonesia, the current flu epicenter, the past year's worries %\!0*(8
about a catastrophic global outbreak largely disappeared.
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What happened? X @)'E9g5:
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Part of the explanation may be seasonal. Bird flu tends to be most vP%:\u:{
active in the colder months, as the virus survives longer at low uY3# ,
temperatures.
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"Many of us are holding our breath to see what happens in the <0jM07\<
winter," said Dr. Malik Peiris, a microbiology professor at Hong ;^)4u
Kong University. "H5N1 spread very rapidly last year," Peiris said. "
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"So the question is, was that a one-off incident?" ~BnmAv$m[
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Some experts suspect poultry vaccination has, paradoxically, {OS[0LB
complicated detection. Vaccination reduces the amount of virus {L M Q
circulating, but low levels of the virus may still be causing }me`(zp
outbreaks - without the obvious signs of dying birds. N Zwi3
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"It's now harder to spot what's happening with the flu in animals DKl\N~{F
and humans," said Dr. Angus Nicoll, influenza director at the w.=rea~
European Centres for Disease Control and Prevention. C2DAsSw
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While the pandemic has not materialized, experts say it's too early oS_YQOoD
to relax. #V Z
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, (Q.I DDlr
coordinator of the World Health Organization's global influenza W4nhPH(
program. But although the virus could mutate into a pandemic strain, #aKUD
Fukuda points out that it might go the other direction instead, \e%%ik,<
becoming less dangerous for humans. j`MK\*qmz
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H5N1 has primarily stalked Asia. This year, however, it crossed the F-D$ Y?m
continental divide, infecting people in Turkey, Iraq, Egypt, >#Bu [nD%
Djibouti, and Azerbaijan. LvL2[xh%&
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But despite the deaths of 154 people, and hundreds of millions of f{{J_""?&
birds worldwide dying or being slaughtered, the virus still has not 1I 8<6pi-
learned how to infect humans easily. k#8E9/ t@
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Flu viruses constantly evolve, so the mere appearance of mutations V2 '5doo
is not enough to raise alarm. The key is to identify which mutations
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are the most worrisome. I(Vg
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"We don't really know how many changes this virus has got to make to [?2,(X0yh1
adapt to humans, if it can at all," said Dr. Richard Webby, a bird Na+h+wD.D
flu expert at St. Jude Children's Research Hospital in Tennessee. $1k@O@F(4
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The most obvious sign that a pandemic may be under way will almost Lw<.QMN%f
certainly come from the field: a sudden spike in cases suggesting *thm )M n
human-to-human transmission. The last pandemic struck in 1968 - when a o@CPB6N
bird flu combined with a human strain and went on to kill 1 million 3L{)Y`P
people worldwide. sR)jZpmC(
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In May, on Sumatra island in Indonesia, a cluster of eight cases was h]j>
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identified, six of whom died. The World Health Organization (?"z!dg c
immediately dispatched a team to investigate. Au:R]7
The U.N. agency was concerned enough by the reports to put D?4bp'0 3
pharmaceuticals company Roche Holding AG on standby in case its Ms-)S7tMz
global antiviral stockpile, promised to WHO for any operation to #WAX&< m
quash an emerging pandemic, needed to be rushed to Indonesia. .=9d3uWJ/
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Luckily, the Sumatra cluster was confined to a single family. Though buhbUmQ2
human-to-human transmission occurred - as it has in a handful of J
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other cases - the virus did not adapt enough to become easily kr-5O 0tmf
infectious. %N0m $*
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This highlighted many of the problems that continue to plague public pX1Us+%
health officials, namely, patchy surveillance systems and limited )mjGHq 2
virus information. t=fP ^bJ
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Even in China, where H5N1 has circulated the longest, surveillance ,T;D33XV
is not ideal. (*AJ6BQWa
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"Monitoring the 14 billion birds in China, especially when most of ]EG8+K6
them are in back yards, is an enormous challenge," said Dr. Henk q$Ms 7 ` a
Bekedam, WHO's top official in China. Of the 21 human cases China kO$n0y5e
has logged so far, 20 were in areas without reported H5N1 outbreaks N 7YCg
in birds. <qEBF`XP =
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"We need to start looking harder for where the virus is hiding," 7xYz9r)w`
Bekedam said. c c/nzB
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To better understand the virus' activity, it would help to have more c;zk
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virus samples from every H5N1-affected country. But public health Ex
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authorities are at the mercy of governments and academics. 15yiDI
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Scientists may hoard viruses while waiting for academic papers to be D0z[h(m
published first. And developing countries may be wary of sharing ,s2C)bb-
virus samples if the vaccines that might be developed from them @]p {%" $
might ultimately be unaffordable. sf:IA%.4t
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That leaves public health officials with an incomplete viral {-f%g-@L6|
picture. oXN(S:ZF
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"It shouldn't just be WHO as a lonely voice in the desert, calling WWo"De@
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu :R>RCR2 g)
expert with the Food and Agriculture Organization in Vietnam. All Mc!LC
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countries, need to understand that sharing will help them better bOp %
prepare for a flu pandemic, he said. {TdxsE >
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Though scientists are bracing themselves for increased bird flu a'. 7)f[g}
activity in the winter, there are no predictions about where it S\Le;,5Z
might appear next. The WHO's Fukuda said it would not be a surprise lnLy"f"zV
to see it appear in new countries.
