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题目:Bird flu and the deteriorating environment .$@R{>%U
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Earlier this year, bird flu panic was in full swing: The French v@# b}N0n
feared for their foie gras, the Swiss locked their chickens indoors, zSb PW 6U
and Americans enlisted prison inmates in Alaska to help spot Ali 9pvE
infected wild birds. KD^N)&k^Kp
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The H5N1 virus - previously confined to Southeast Asia - was <]G]W/eB'
striking birds in places as diverse as Germany, Egypt, and Nigeria, ``E/m<r:$
and a flu pandemic seemed inevitable. Mfv1Os:ST
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Then the virus went quiet. Except for a steady stream of human cases VE 8;sGaJ
in Indonesia, the current flu epicenter, the past year's worries P (S>=,Y&
about a catastrophic global outbreak largely disappeared. J:skJ.W x
What happened? "*})3['n
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Part of the explanation may be seasonal. Bird flu tends to be most rSrIEP,c'
active in the colder months, as the virus survives longer at low
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"Many of us are holding our breath to see what happens in the zhf.NCSt(
winter," said Dr. Malik Peiris, a microbiology professor at Hong gJM`[x`T
Kong University. "H5N1 spread very rapidly last year," Peiris said. rl0< Ls
"So the question is, was that a one-off incident?" 7k8 pZ
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Some experts suspect poultry vaccination has, paradoxically, :kGU,>BN
complicated detection. Vaccination reduces the amount of virus o *J3C>
circulating, but low levels of the virus may still be causing p}cw{
outbreaks - without the obvious signs of dying birds. NC38fiH_N
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"It's now harder to spot what's happening with the flu in animals ~
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and humans," said Dr. Angus Nicoll, influenza director at the z^<"x |:
European Centres for Disease Control and Prevention. RU\
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While the pandemic has not materialized, experts say it's too early R2
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to relax. 9 yfJVg
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, E@b(1@
coordinator of the World Health Organization's global influenza VTH>
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program. But although the virus could mutate into a pandemic strain, sQ\8>[]
Fukuda points out that it might go the other direction instead, =y!$/(H
becoming less dangerous for humans. ?[ lV -
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H5N1 has primarily stalked Asia. This year, however, it crossed the @!1x7%]G
continental divide, infecting people in Turkey, Iraq, Egypt, a8UwhjFO
Djibouti, and Azerbaijan. 9c("x%nLpB
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But despite the deaths of 154 people, and hundreds of millions of Kh_Lp$'0uM
birds worldwide dying or being slaughtered, the virus still has not RtM8yar+sn
learned how to infect humans easily. *vwbgJG! *
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Flu viruses constantly evolve, so the mere appearance of mutations +O?KNZ
is not enough to raise alarm. The key is to identify which mutations gK'1ZLdZ2
are the most worrisome. mrF58Uq;A
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"We don't really know how many changes this virus has got to make to ~XmLX)vO/
adapt to humans, if it can at all," said Dr. Richard Webby, a bird m()RU"WY
flu expert at St. Jude Children's Research Hospital in Tennessee. v : OR
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The most obvious sign that a pandemic may be under way will almost 2OVRf0.R~
certainly come from the field: a sudden spike in cases suggesting A"dR{8&0
human-to-human transmission. The last pandemic struck in 1968 - when i\r
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bird flu combined with a human strain and went on to kill 1 million ?Yth0O6?sb
people worldwide. ,N]H dR
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In May, on Sumatra island in Indonesia, a cluster of eight cases was .ufTQ?Fe
identified, six of whom died. The World Health Organization zGkS ^Z=(
immediately dispatched a team to investigate.
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The U.N. agency was concerned enough by the reports to put P uA9X[=
pharmaceuticals company Roche Holding AG on standby in case its z
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global antiviral stockpile, promised to WHO for any operation to iW%I|&
quash an emerging pandemic, needed to be rushed to Indonesia. %Q
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Luckily, the Sumatra cluster was confined to a single family. Though 1VG4S){}\9
human-to-human transmission occurred - as it has in a handful of !h23cj+V
other cases - the virus did not adapt enough to become easily K<SyC54
infectious. _u5#v0Y
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This highlighted many of the problems that continue to plague public @ hiCI.?X
health officials, namely, patchy surveillance systems and limited Bn#?zI
virus information. ~=6xyc /c
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Even in China, where H5N1 has circulated the longest, surveillance -.u]GeMy
is not ideal. ' g=
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"Monitoring the 14 billion birds in China, especially when most of c[wla<dO*
them are in back yards, is an enormous challenge," said Dr. Henk eTI
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Bekedam, WHO's top official in China. Of the 21 human cases China AN8`7F1
has logged so far, 20 were in areas without reported H5N1 outbreaks SPX$ U5&
in birds. 7~^GA.92
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"We need to start looking harder for where the virus is hiding," EUD~CZhS"k
Bekedam said. = 9'RM >
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To better understand the virus' activity, it would help to have more c }Ft^Il
virus samples from every H5N1-affected country. But public health E4`N-3
authorities are at the mercy of governments and academics. n7B7 m,@1
Scientists may hoard viruses while waiting for academic papers to be Zd^rNHhA
published first. And developing countries may be wary of sharing twL3\
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virus samples if the vaccines that might be developed from them Su
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might ultimately be unaffordable. m ,* QP*
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That leaves public health officials with an incomplete viral ?i7%x,g(Z
picture. 1->dMm}G[
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"It shouldn't just be WHO as a lonely voice in the desert, calling q
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for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu ypbe!Y<i]
expert with the Food and Agriculture Organization in Vietnam. All
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countries, need to understand that sharing will help them better 9oyE$S h]
prepare for a flu pandemic, he said. +6sy-<ZL:
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Though scientists are bracing themselves for increased bird flu H7z,j}l
activity in the winter, there are no predictions about where it Od ) Uv1
might appear next. The WHO's Fukuda said it would not be a surprise bx#>BK!
to see it appear in new countries.
