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题目:Bird flu and the deteriorating environment 0- )K_JV
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Earlier this year, bird flu panic was in full swing: The French c>B1cR
feared for their foie gras, the Swiss locked their chickens indoors, mLxgvp
and Americans enlisted prison inmates in Alaska to help spot ){5Nod{}a
infected wild birds. bx8](cT_
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The H5N1 virus - previously confined to Southeast Asia - was 'p&,'+x
striking birds in places as diverse as Germany, Egypt, and Nigeria, YB5"i9T2
and a flu pandemic seemed inevitable. bP&Q Fc
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Then the virus went quiet. Except for a steady stream of human cases :CyHo 6o9
in Indonesia, the current flu epicenter, the past year's worries ZD]1C ~)
about a catastrophic global outbreak largely disappeared. [ >O!~
What happened? +(3_V$|Dv
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Part of the explanation may be seasonal. Bird flu tends to be most hz
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active in the colder months, as the virus survives longer at low bO=|utpk
temperatures. - b(DPte
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"Many of us are holding our breath to see what happens in the E#B-JLMGl
winter," said Dr. Malik Peiris, a microbiology professor at Hong Hc)z:x;Sj
Kong University. "H5N1 spread very rapidly last year," Peiris said. ')y 2W1
"So the question is, was that a one-off incident?" 7
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Some experts suspect poultry vaccination has, paradoxically, 9zu;OK%
complicated detection. Vaccination reduces the amount of virus
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circulating, but low levels of the virus may still be causing 2r,
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outbreaks - without the obvious signs of dying birds. ->sxz/L
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"It's now harder to spot what's happening with the flu in animals 4b
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and humans," said Dr. Angus Nicoll, influenza director at the B*(]T|ff<
European Centres for Disease Control and Prevention. u^"
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While the pandemic has not materialized, experts say it's too early -*C
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to relax. bdg6B 7%Q
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, =&}@GsXdo
coordinator of the World Health Organization's global influenza AUnfhk@$
program. But although the virus could mutate into a pandemic strain, XUqorE
Fukuda points out that it might go the other direction instead, //R"ZE@d\
becoming less dangerous for humans. M3(N!xT
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H5N1 has primarily stalked Asia. This year, however, it crossed the ma.84~m
continental divide, infecting people in Turkey, Iraq, Egypt, m{\
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Djibouti, and Azerbaijan. *_(X$qfoW
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But despite the deaths of 154 people, and hundreds of millions of {w@qFE' b
birds worldwide dying or being slaughtered, the virus still has not F-_u/C]
learned how to infect humans easily. @) Qgy}*5
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Flu viruses constantly evolve, so the mere appearance of mutations 9]4Q@%
is not enough to raise alarm. The key is to identify which mutations 3SVGx< ,2
are the most worrisome. 5 \ mRH
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"We don't really know how many changes this virus has got to make to eV9U+]C `
adapt to humans, if it can at all," said Dr. Richard Webby, a bird [9m3@Yd'
flu expert at St. Jude Children's Research Hospital in Tennessee. O0 'iq^g
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The most obvious sign that a pandemic may be under way will almost 0=Z[6Q@ :
certainly come from the field: a sudden spike in cases suggesting ++cS^ Lo
human-to-human transmission. The last pandemic struck in 1968 - when -+R,="nRQ
bird flu combined with a human strain and went on to kill 1 million UP~28%>X
people worldwide. (MwRe?Ih
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In May, on Sumatra island in Indonesia, a cluster of eight cases was cgnNO&
identified, six of whom died. The World Health Organization R h>B#
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immediately dispatched a team to investigate. (b&g4$!x&5
The U.N. agency was concerned enough by the reports to put 7'0V b !(
pharmaceuticals company Roche Holding AG on standby in case its Ji4p6$ .j-
global antiviral stockpile, promised to WHO for any operation to TW|K.t@5#H
quash an emerging pandemic, needed to be rushed to Indonesia. 2+1ybOwb
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Luckily, the Sumatra cluster was confined to a single family. Though {6i|"5_j
human-to-human transmission occurred - as it has in a handful of D#;7S'C
other cases - the virus did not adapt enough to become easily X\^V{v^-
infectious. fBS a8D3}`
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This highlighted many of the problems that continue to plague public rH@Rh}#yp
health officials, namely, patchy surveillance systems and limited ' zyw-1
virus information. 8$( I! ;
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Even in China, where H5N1 has circulated the longest, surveillance %rwvY`\
is not ideal. H:fKv7XL
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"Monitoring the 14 billion birds in China, especially when most of HuhQ|~C+~
them are in back yards, is an enormous challenge," said Dr. Henk (W 1 $+X
Bekedam, WHO's top official in China. Of the 21 human cases China pH '_k k
has logged so far, 20 were in areas without reported H5N1 outbreaks nY'V, v [F
in birds. w~ Tg?RH:
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"We need to start looking harder for where the virus is hiding," ^rWg:f
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Bekedam said. 5`h$^l/
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To better understand the virus' activity, it would help to have more =?5)M_6)
virus samples from every H5N1-affected country. But public health O8]e(i
authorities are at the mercy of governments and academics. ,54z9F`
Scientists may hoard viruses while waiting for academic papers to be Gwd38
published first. And developing countries may be wary of sharing q/O2E<=w*c
virus samples if the vaccines that might be developed from them j=r1JV
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might ultimately be unaffordable. :=Olp;+_
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That leaves public health officials with an incomplete viral { 'b;lA]0
picture. b RAD_
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"It shouldn't just be WHO as a lonely voice in the desert, calling 7^dr[.Q[*
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu al
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expert with the Food and Agriculture Organization in Vietnam. All ] Q5:JV
countries, need to understand that sharing will help them better 3 FBL CD3
prepare for a flu pandemic, he said. ifD WN*k6
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Though scientists are bracing themselves for increased bird flu BA@E
activity in the winter, there are no predictions about where it Oe5rRQ$ O
might appear next. The WHO's Fukuda said it would not be a surprise K43 %9=sM
to see it appear in new countries.
