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题目:Bird flu and the deteriorating environment e Sf
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Earlier this year, bird flu panic was in full swing: The French {?m;D Y v
feared for their foie gras, the Swiss locked their chickens indoors, YgiwtZ5FY
and Americans enlisted prison inmates in Alaska to help spot s.+2[R1HF
infected wild birds. ;V ]EF
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The H5N1 virus - previously confined to Southeast Asia - was 1><\3+8
striking birds in places as diverse as Germany, Egypt, and Nigeria, !PUbaF-.6
and a flu pandemic seemed inevitable. L'=2Uk#.D
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Then the virus went quiet. Except for a steady stream of human cases 0HK0 3&
in Indonesia, the current flu epicenter, the past year's worries e&Z}struE
about a catastrophic global outbreak largely disappeared. E< nXkqD
What happened? 49n .Gc
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Part of the explanation may be seasonal. Bird flu tends to be most Ao)hb4ex
active in the colder months, as the virus survives longer at low h+F@apUS
temperatures. cAJK
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"Many of us are holding our breath to see what happens in the rm2"pfs
winter," said Dr. Malik Peiris, a microbiology professor at Hong [Z6]$$!#2
Kong University. "H5N1 spread very rapidly last year," Peiris said. GXB4&Q!C
"So the question is, was that a one-off incident?" Q(h,P+
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Some experts suspect poultry vaccination has, paradoxically, n
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complicated detection. Vaccination reduces the amount of virus =BJ/ZM
circulating, but low levels of the virus may still be causing i.2O~30ST
outbreaks - without the obvious signs of dying birds. s` F v!
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"It's now harder to spot what's happening with the flu in animals ep<A
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and humans," said Dr. Angus Nicoll, influenza director at the +kTAOf M
European Centres for Disease Control and Prevention. m>2b %GTh
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While the pandemic has not materialized, experts say it's too early m3XL;1y:a
to relax. OqUEj 0 X
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, f|Kd{ $VO
coordinator of the World Health Organization's global influenza I=&5m g=m
program. But although the virus could mutate into a pandemic strain, #C|:] moe
Fukuda points out that it might go the other direction instead, @va{&i`%A7
becoming less dangerous for humans. 0TU~Q
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H5N1 has primarily stalked Asia. This year, however, it crossed the K,tmh1
continental divide, infecting people in Turkey, Iraq, Egypt, ;+K:^*oJ
Djibouti, and Azerbaijan. V S2p"0$3D
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But despite the deaths of 154 people, and hundreds of millions of _6THyj$f
birds worldwide dying or being slaughtered, the virus still has not 1iaNb[:QX
learned how to infect humans easily. oju/%ieh
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Flu viruses constantly evolve, so the mere appearance of mutations tr7FV1p
is not enough to raise alarm. The key is to identify which mutations 8<3J!X+
are the most worrisome. {.
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"We don't really know how many changes this virus has got to make to .{H
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adapt to humans, if it can at all," said Dr. Richard Webby, a bird T 2Cdw\
flu expert at St. Jude Children's Research Hospital in Tennessee. bj(U?$
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The most obvious sign that a pandemic may be under way will almost ?nrd$,
certainly come from the field: a sudden spike in cases suggesting E&
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human-to-human transmission. The last pandemic struck in 1968 - when _]1dm)%
bird flu combined with a human strain and went on to kill 1 million zF< *h ~
people worldwide. 3nd02:
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In May, on Sumatra island in Indonesia, a cluster of eight cases was $rs7D}VNc
identified, six of whom died. The World Health Organization `>rdn*B
immediately dispatched a team to investigate. PmvTCfsg
The U.N. agency was concerned enough by the reports to put [:a;|t
pharmaceuticals company Roche Holding AG on standby in case its ~Ht[kO
global antiviral stockpile, promised to WHO for any operation to zdyS"H}
quash an emerging pandemic, needed to be rushed to Indonesia. ?Z(
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Luckily, the Sumatra cluster was confined to a single family. Though P_hwa1~d
human-to-human transmission occurred - as it has in a handful of 7R<<}dA]
other cases - the virus did not adapt enough to become easily \PU|<Ru.
infectious. Il'+^u_ <
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This highlighted many of the problems that continue to plague public ~c! XQJ
health officials, namely, patchy surveillance systems and limited U;;vNzcn
virus information. nXb;&n%
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Even in China, where H5N1 has circulated the longest, surveillance s~]Ri:7~
is not ideal. oO$a4|&,
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"Monitoring the 14 billion birds in China, especially when most of vNd 4Fn)H
them are in back yards, is an enormous challenge," said Dr. Henk fseHuL=~
Bekedam, WHO's top official in China. Of the 21 human cases China }c| Xr^
has logged so far, 20 were in areas without reported H5N1 outbreaks d;:+Xd
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"We need to start looking harder for where the virus is hiding," 4punJg~1
Bekedam said. JDD(e_dw
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To better understand the virus' activity, it would help to have more {#zJx(2yG
virus samples from every H5N1-affected country. But public health 72& xEx
authorities are at the mercy of governments and academics. F,P, dc
Scientists may hoard viruses while waiting for academic papers to be . AW Re1?
published first. And developing countries may be wary of sharing }a'8lwF%I
virus samples if the vaccines that might be developed from them / "~CWNa
might ultimately be unaffordable.
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That leaves public health officials with an incomplete viral !H Y +6!hk
picture. 7 H.2]X
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"It shouldn't just be WHO as a lonely voice in the desert, calling [wjA8d.
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu AHIk 7[w
expert with the Food and Agriculture Organization in Vietnam. All bv4lgRE6Y
countries, need to understand that sharing will help them better =sG C
prepare for a flu pandemic, he said. m.&z:`x[
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Though scientists are bracing themselves for increased bird flu bs
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activity in the winter, there are no predictions about where it [_^K }\ /+
might appear next. The WHO's Fukuda said it would not be a surprise @@# ^G8+l
to see it appear in new countries.
