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题目:Bird flu and the deteriorating environment ,S, R6#3G
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Earlier this year, bird flu panic was in full swing: The French 1JI7P?\B
feared for their foie gras, the Swiss locked their chickens indoors, ZQ_~
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and Americans enlisted prison inmates in Alaska to help spot x^pHP|<3`
infected wild birds. ]tbl1=|
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The H5N1 virus - previously confined to Southeast Asia - was z KG]7
striking birds in places as diverse as Germany, Egypt, and Nigeria, mT1Q7ta*P
and a flu pandemic seemed inevitable. o 7 &q
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Then the virus went quiet. Except for a steady stream of human cases T=pKen /
in Indonesia, the current flu epicenter, the past year's worries zn\$6'"
about a catastrophic global outbreak largely disappeared. 6" . v6
What happened? EixAm G
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Part of the explanation may be seasonal. Bird flu tends to be most x&FBh !5H
active in the colder months, as the virus survives longer at low KVpQ,x&q~
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"Many of us are holding our breath to see what happens in the T@N)BfkB
winter," said Dr. Malik Peiris, a microbiology professor at Hong #j"N5e}U
Kong University. "H5N1 spread very rapidly last year," Peiris said. DEKO] i
"So the question is, was that a one-off incident?" DEpn>
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Some experts suspect poultry vaccination has, paradoxically, +r_ _> V,
complicated detection. Vaccination reduces the amount of virus K%>3ev=y.s
circulating, but low levels of the virus may still be causing brt` oR
outbreaks - without the obvious signs of dying birds. TbhsOf!
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"It's now harder to spot what's happening with the flu in animals #TY[\$ BHs
and humans," said Dr. Angus Nicoll, influenza director at the CLY>M`%?+p
European Centres for Disease Control and Prevention. ~px)Jd
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While the pandemic has not materialized, experts say it's too early CjlA"_!%E
to relax. AG<TY<nqL
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, GF awmN
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coordinator of the World Health Organization's global influenza (e6KSRh2fF
program. But although the virus could mutate into a pandemic strain, Cr$8\{2OA7
Fukuda points out that it might go the other direction instead, e' t1.%w
becoming less dangerous for humans. Z?tw#n[T
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H5N1 has primarily stalked Asia. This year, however, it crossed the D<XRu4^;
continental divide, infecting people in Turkey, Iraq, Egypt, 9q
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Djibouti, and Azerbaijan.
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But despite the deaths of 154 people, and hundreds of millions of rpO>l
birds worldwide dying or being slaughtered, the virus still has not jneos~ 'n8
learned how to infect humans easily. e. ksN
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Flu viruses constantly evolve, so the mere appearance of mutations ^5d9n<_xnQ
is not enough to raise alarm. The key is to identify which mutations `SSUQ#@
are the most worrisome. GLIP;)h1
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"We don't really know how many changes this virus has got to make to A i lfeHG
adapt to humans, if it can at all," said Dr. Richard Webby, a bird 8cyC\Rs
flu expert at St. Jude Children's Research Hospital in Tennessee. !u=,b fyH
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The most obvious sign that a pandemic may be under way will almost trC+Etc
certainly come from the field: a sudden spike in cases suggesting gELb(Y\ak
human-to-human transmission. The last pandemic struck in 1968 - when rCa2$#Z
bird flu combined with a human strain and went on to kill 1 million Bpw <{U
people worldwide. _z
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In May, on Sumatra island in Indonesia, a cluster of eight cases was DfQD !}=
identified, six of whom died. The World Health Organization cWA$O*A
immediately dispatched a team to investigate. 2i3& 3oz]O
The U.N. agency was concerned enough by the reports to put {? dW-
pharmaceuticals company Roche Holding AG on standby in case its sB,>4*Zd
global antiviral stockpile, promised to WHO for any operation to ].eY]o}=
quash an emerging pandemic, needed to be rushed to Indonesia. br 9`77J8
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Luckily, the Sumatra cluster was confined to a single family. Though ~t~5 ctJ@
human-to-human transmission occurred - as it has in a handful of 'Na/AcRdg
other cases - the virus did not adapt enough to become easily !cWnQRIt_F
infectious. q|A
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This highlighted many of the problems that continue to plague public Um$a9S8b&
health officials, namely, patchy surveillance systems and limited S}hg*mWn{$
virus information. XTZI !
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Even in China, where H5N1 has circulated the longest, surveillance PUN.n
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is not ideal. ^g
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"Monitoring the 14 billion birds in China, especially when most of kPVP+}cA
them are in back yards, is an enormous challenge," said Dr. Henk y{eZ rX|
Bekedam, WHO's top official in China. Of the 21 human cases China +"] 'h~W
has logged so far, 20 were in areas without reported H5N1 outbreaks ^w<:UE2a!
in birds. a91Q*X%
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"We need to start looking harder for where the virus is hiding," iDO~G($C
Bekedam said. 5m+:GiI
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To better understand the virus' activity, it would help to have more #oYX0wv l
virus samples from every H5N1-affected country. But public health ``kKi3TWJ
authorities are at the mercy of governments and academics. %;9e h'
Scientists may hoard viruses while waiting for academic papers to be l1o dkNf|
published first. And developing countries may be wary of sharing uF T\a=
virus samples if the vaccines that might be developed from them Iw"?%k\U
might ultimately be unaffordable. 2 597#O
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That leaves public health officials with an incomplete viral |y%pP/;&!
picture. "0L@cOy
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"It shouldn't just be WHO as a lonely voice in the desert, calling ,)L.^<
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu q0y ?$XS
expert with the Food and Agriculture Organization in Vietnam. All j7-#">Y
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countries, need to understand that sharing will help them better 4r(rWlM
prepare for a flu pandemic, he said. fWm;cDM
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Though scientists are bracing themselves for increased bird flu v;K\#uc_
activity in the winter, there are no predictions about where it "E 2
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might appear next. The WHO's Fukuda said it would not be a surprise <{-DYRiN
to see it appear in new countries.
