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题目:Bird flu and the deteriorating environment 4R/cN' -
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Earlier this year, bird flu panic was in full swing: The French P6ztP$M(
feared for their foie gras, the Swiss locked their chickens indoors, .v{ok,&
and Americans enlisted prison inmates in Alaska to help spot aqk0+
infected wild birds. 6eh\-+=
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The H5N1 virus - previously confined to Southeast Asia - was J
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striking birds in places as diverse as Germany, Egypt, and Nigeria, cn$o$:tW
and a flu pandemic seemed inevitable. * Jy'3o
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Then the virus went quiet. Except for a steady stream of human cases U- UD27
in Indonesia, the current flu epicenter, the past year's worries u2G{I?
about a catastrophic global outbreak largely disappeared. +I {ZW}rA
What happened? G
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Part of the explanation may be seasonal. Bird flu tends to be most mu[:b
active in the colder months, as the virus survives longer at low < :mV^tK
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"Many of us are holding our breath to see what happens in the 2L<iIBSJwm
winter," said Dr. Malik Peiris, a microbiology professor at Hong &?R2 zfcM
Kong University. "H5N1 spread very rapidly last year," Peiris said. `*J;4Ju@
"So the question is, was that a one-off incident?" p=7
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Some experts suspect poultry vaccination has, paradoxically, l$PSID
complicated detection. Vaccination reduces the amount of virus G^`IfF-j
circulating, but low levels of the virus may still be causing 6 V" |
outbreaks - without the obvious signs of dying birds. \DG
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"It's now harder to spot what's happening with the flu in animals ^u? # fLr
and humans," said Dr. Angus Nicoll, influenza director at the .$r=:k_d
European Centres for Disease Control and Prevention. Z r}5)ZR.
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While the pandemic has not materialized, experts say it's too early </UUvMf"
to relax. p(jY2&g
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"We have a visible risk in front of us," said Dr. Keiji Fukuda, ?s=O6D&
coordinator of the World Health Organization's global influenza 5r *5Co+
program. But although the virus could mutate into a pandemic strain, W chu-]
Fukuda points out that it might go the other direction instead, CFm(
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becoming less dangerous for humans. q#{.8H-X'
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H5N1 has primarily stalked Asia. This year, however, it crossed the {XHAQ9'
continental divide, infecting people in Turkey, Iraq, Egypt, q c(R
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Djibouti, and Azerbaijan. :~I^ni
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But despite the deaths of 154 people, and hundreds of millions of uPVM>xf>w
birds worldwide dying or being slaughtered, the virus still has not 03ol6y )C
learned how to infect humans easily. scf.> K2
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Flu viruses constantly evolve, so the mere appearance of mutations o!]muO*Rm
is not enough to raise alarm. The key is to identify which mutations mH1 T|UI
are the most worrisome. ~[_u@8l!mN
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"We don't really know how many changes this virus has got to make to B0h|Y.S8%1
adapt to humans, if it can at all," said Dr. Richard Webby, a bird (yx^zW7
flu expert at St. Jude Children's Research Hospital in Tennessee. x7<2K(
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The most obvious sign that a pandemic may be under way will almost 6'{/Ot e
certainly come from the field: a sudden spike in cases suggesting <
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human-to-human transmission. The last pandemic struck in 1968 - when Dias!$g
bird flu combined with a human strain and went on to kill 1 million H*m3i;"4p\
people worldwide. kB)u@`</mV
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In May, on Sumatra island in Indonesia, a cluster of eight cases was :*=fGwIWS
identified, six of whom died. The World Health Organization _%@d lT?
immediately dispatched a team to investigate. bu ? 4$O
The U.N. agency was concerned enough by the reports to put W\c1Q Y$E
pharmaceuticals company Roche Holding AG on standby in case its yTxrbE
global antiviral stockpile, promised to WHO for any operation to )+ V)]dS@%
quash an emerging pandemic, needed to be rushed to Indonesia. %eE0a4^".
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Luckily, the Sumatra cluster was confined to a single family. Though _qxBjB4t"a
human-to-human transmission occurred - as it has in a handful of }@y(-7t
other cases - the virus did not adapt enough to become easily gTS} 'w{
infectious. |AQU\B Uj
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This highlighted many of the problems that continue to plague public Ob&m&2s,
health officials, namely, patchy surveillance systems and limited j* ZU}Ss
virus information. Tc .Qz D\
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Even in China, where H5N1 has circulated the longest, surveillance y
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is not ideal. { E;oirv&
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"Monitoring the 14 billion birds in China, especially when most of 2 oF1do ;
them are in back yards, is an enormous challenge," said Dr. Henk ^OOoo2
Bekedam, WHO's top official in China. Of the 21 human cases China 3#0y.. F
has logged so far, 20 were in areas without reported H5N1 outbreaks #`ZBA>FLaQ
in birds. 2lCgUe)
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"We need to start looking harder for where the virus is hiding," |vw], r6
Bekedam said. % Z 3B9
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To better understand the virus' activity, it would help to have more RW
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virus samples from every H5N1-affected country. But public health Hz"FGwd
authorities are at the mercy of governments and academics. 2 :4o`o
Scientists may hoard viruses while waiting for academic papers to be @
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published first. And developing countries may be wary of sharing m5o$Dus+?'
virus samples if the vaccines that might be developed from them gZ| !'
might ultimately be unaffordable. l;r A}?,.^
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That leaves public health officials with an incomplete viral o`Af6C;Q
picture. A>8~deZ9
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"It shouldn't just be WHO as a lonely voice in the desert, calling E 4'z
for more viruses (to be shared)," said Dr. Jeff Gilbert, a bird flu +w7U7"
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expert with the Food and Agriculture Organization in Vietnam. All 2 +/r~LwbK
countries, need to understand that sharing will help them better :7i x`C2
prepare for a flu pandemic, he said. 6<9}>Wkf
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Though scientists are bracing themselves for increased bird flu 3 l}9'j
activity in the winter, there are no predictions about where it _^eiN'B
might appear next. The WHO's Fukuda said it would not be a surprise (?g+.]Dt,
to see it appear in new countries.
