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题目:Bird flu and the deteriorating environment ;Su-Y!& %
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Earlier this year, bird flu panic was in full swing: The French ,!@ ML n
feared for their foie gras, the Swiss locked their chickens indoors, pv sa?z;rP
and Americans enlisted prison inmates in Alaska to help spot Y
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infected wild birds. sH;_U)ssH
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The H5N1 virus - previously confined to Southeast Asia - was T:Nk9t$W7@
striking birds in places as diverse as Germany, Egypt, and Nigeria, >@Ht*h{~
and a flu pandemic seemed inevitable. 5!fYTo|G>
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Then the virus went quiet. Except for a steady stream of human cases ls:oC},p*
in Indonesia, the current flu epicenter, the past year's worries e 9RY k:O
about a catastrophic global outbreak largely disappeared. e
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What happened? A2:}bb~H
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Part of the explanation may be seasonal. Bird flu tends to be most rf% lhBv
active in the colder months, as the virus survives longer at low J|f29 B-c
temperatures. > B@ c74
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"Many of us are holding our breath to see what happens in the r5S/lp+Y+N
winter," said Dr. Malik Peiris, a microbiology professor at Hong 15 Mt lb
Kong University. "H5N1 spread very rapidly last year," Peiris said. oH%[8!#
"So the question is, was that a one-off incident?" ~ W8X g)
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Some experts suspect poultry vaccination has, paradoxically, +|obU9M
complicated detection. Vaccination reduces the amount of virus 4-x<^
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circulating, but low levels of the virus may still be causing F6[F~^9D
outbreaks - without the obvious signs of dying birds. zFExYY d
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"It's now harder to spot what's happening with the flu in animals .5G` Y
and humans," said Dr. Angus Nicoll, influenza director at the F &czD;F
European Centres for Disease Control and Prevention. [cd1Mf:[Y
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While the pandemic has not materialized, experts say it's too early M.mn9k w`
to relax. W3
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, `-pw P
coordinator of the World Health Organization's global influenza #! R>`l(S
program. But although the virus could mutate into a pandemic strain, e`qrafa
Fukuda points out that it might go the other direction instead, CXuD%H]tx
becoming less dangerous for humans. c{/R?<
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H5N1 has primarily stalked Asia. This year, however, it crossed the d,(y$V+
continental divide, infecting people in Turkey, Iraq, Egypt, 1PwtzH .w
Djibouti, and Azerbaijan. ~rBFP)
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But despite the deaths of 154 people, and hundreds of millions of LBy`N _@
birds worldwide dying or being slaughtered, the virus still has not
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learned how to infect humans easily. 9<_hb1'
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Flu viruses constantly evolve, so the mere appearance of mutations MM32\}Y6
is not enough to raise alarm. The key is to identify which mutations QIk FX.^
are the most worrisome. pqO3(
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"We don't really know how many changes this virus has got to make to */K[ B(G
adapt to humans, if it can at all," said Dr. Richard Webby, a bird i<M s2^
flu expert at St. Jude Children's Research Hospital in Tennessee. I MD^(k 2
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The most obvious sign that a pandemic may be under way will almost @M\JzV4 A[
certainly come from the field: a sudden spike in cases suggesting J0IKI,X.
human-to-human transmission. The last pandemic struck in 1968 - when k H65k (
bird flu combined with a human strain and went on to kill 1 million wBpt
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people worldwide. \/1~5mQ+
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In May, on Sumatra island in Indonesia, a cluster of eight cases was h's[)
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identified, six of whom died. The World Health Organization rrU(>jA!
immediately dispatched a team to investigate. On);SN'
The U.N. agency was concerned enough by the reports to put "-S!^h/v
pharmaceuticals company Roche Holding AG on standby in case its yam'LF
global antiviral stockpile, promised to WHO for any operation to wrJQkven-
quash an emerging pandemic, needed to be rushed to Indonesia. Z6gwAvf<
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Luckily, the Sumatra cluster was confined to a single family. Though 3\ajnd|
human-to-human transmission occurred - as it has in a handful of MMa`}wSs
other cases - the virus did not adapt enough to become easily J L_(%._J
infectious. ]kNxytH\o
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This highlighted many of the problems that continue to plague public 7Z]?a
health officials, namely, patchy surveillance systems and limited BpA7
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virus information. IJ.H/l}h
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Even in China, where H5N1 has circulated the longest, surveillance tx;2C|S$oU
is not ideal. A["6dbvv
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"Monitoring the 14 billion birds in China, especially when most of 7]u_
them are in back yards, is an enormous challenge," said Dr. Henk yT% <
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Bekedam, WHO's top official in China. Of the 21 human cases China dT1UYG}>j
has logged so far, 20 were in areas without reported H5N1 outbreaks )`k+Oyvi<
in birds. Q >yj<DR
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"We need to start looking harder for where the virus is hiding," hDJ+Rk@
Bekedam said. i{:?Iw 'ay
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To better understand the virus' activity, it would help to have more 4myikeUR_
virus samples from every H5N1-affected country. But public health
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authorities are at the mercy of governments and academics. .h
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Scientists may hoard viruses while waiting for academic papers to be x6T$HN/2
published first. And developing countries may be wary of sharing LfnQcI$kO
virus samples if the vaccines that might be developed from them T}p|_)&y
might ultimately be unaffordable. %,N-M]Jf
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That leaves public health officials with an incomplete viral U GOe(JB
picture. ;(g"=9
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"It shouldn't just be WHO as a lonely voice in the desert, calling B
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for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu |c]L]PU
expert with the Food and Agriculture Organization in Vietnam. All y(Pv1=e
countries, need to understand that sharing will help them better
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prepare for a flu pandemic, he said. 48GaZ@v
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Though scientists are bracing themselves for increased bird flu gcM(K.n
activity in the winter, there are no predictions about where it )]}68}9
might appear next. The WHO's Fukuda said it would not be a surprise \iwUsv>SB
to see it appear in new countries.
