Killer Flu Virus Changes Its Skin - Ingredients for Worldwide Flu Epidemic
Brewing in China
By Daniel DeNoon
June 17, 2002 -- It happened three times in the last century -- and nearly
happened again in 1997. Now experts say that another killer flu epidemic is
Will it emerge to kill millions -- as did the 1918 Spanish flu? Or will it
be nipped in the bud, as in the 1997 emergence of chicken flu in humans?
There are no easy answers. But now the same experts who led the successful
effort to stop the 1997 virus in Hong Kong raise troubling new questions.
Those questions come from a report in the June 25 issue of the prestigious
Proceedings of the National Academy of Sciences. The report shows that flu
viruses similar to the killer 1997 strain reappeared in Hong Kong in 2001.
It happened again this year, the authors now say.
"We don't want this in humans or the world will be in deep, deep
researcher Robert G. Webster, PhD, tells WebMD. "What will you do if one of
these gets away? You haven't got anything to do. Are we going to be
prepared for this? It is going to happen sooner or later, and authorities
are not stockpiling effective drugs. We have had two years of very mild
flu, and now these drugs are in very short supply. If one of these viruses
gets away, we are in for trouble."
And while none of the 2001 or 2002 viruses infected humans, they had
acquired dangerous new genes. Lab mice exposed to some of these viruses
quickly developed brain infections and died. Webster is director of the
World Health Organization collaborating center on influenza viruses in
lower animals and birds.
Flu viruses can change their genes to become more infectious and more
deadly to humans. The new study shows that the potentially deadly Hong Kong
flu virus known as H5N1 has been shifting in alarming ways.
"This time, this virus has picked up a whole set of new internal
Webster says. "What worries me is this shows it is possible for this virus
to 'mate' with a number of different viruses and produce viruses highly
[lethal] for poultry. The key question is, 'What is the potential in
humans?' Can you afford to let the experiment happen? The worrying thing is
that all these original viruses continue to circulate. If this virus mates
with a virus that allows it to spread from human to human, it would be of
great worry to me."
David L. Suarez, DVM, PhD, is lead scientist for avian influenza at the
U.S. Department of Agriculture's Southeast Poultry Research Laboratory in
Athens, Ga. He's the point man for U.S. efforts to track emerging flu
epidemics in poultry.
"There is danger of human infection -- the risk is not zero," Suarez
WebMD. "The major concern is that the genes that made up the 1997 outbreak
are still circulating. Fortunately, we haven't seen a virus with the same
set of genes as in 1997, but the fear is that we could always see something
Another author of the PNAS study is J.S. Malik Peiris, MD, PhD, professor
of microbiology at the University of Hong Kong. Peiris points out that none
of the H5N1 viruses seen since 1997 had the right gene combination to let
them infect humans.
But Peiris also says that we should not be concentrating solely on the H5N1
viruses as a possible cause of a global flu epidemic. A number of other
influenza viruses -- some more widespread than H5N1 -- also deserve close
attention, he says.
In 1997, Hong Kong authorities had all of the city's 3 million chickens
slaughtered. While there were 18 human infections and eight deaths, all of
these infections came directly from birds. Killing the poultry stopped the
outbreak before the virus could learn to spread from human to human. It was
a close call -- and the first time a human action prevented a worldwide
In 2001, Hong Kong authorities again ordered the deaths of hundreds of
thousands of chickens. They also established strict new rules for the
area's poultry farmers and live-poultry markets. Affected chickens were
killed this year, too, but a new poultry vaccine was used to prevent spread
among uninfected birds. Unfortunately, no such safeguards are in place in
Mainland China is still denying they have a problem, Saurez says. "For me
it is a very big concern." Every year since 1997 we have seen flu viruses
that cause severe disease -- the source for which was China, he says. "It
is there. So obviously they are unable or unwilling to control it. It is a
"..It does not require a majority to prevail, but rather an irate, tireless
minority keen to set brush fires in people's minds.." Samuel Adams
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