Stopping the Killer Virus

[Dave Farber <dave () farber net>]

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From: Claudio Gutiérrez <gutierrezclaudio () terra cl>
Date: Fri, 11 Apr 2003 12:36:46 -0400
To: dave () farber net
Subject: Stopping the Killer Virus

Dave:
could be of interest of IP

Stopping the Killer Virus
Robert Langreth and Emily Lambert, 04.28.03

Behind the race to contain the Asian pneumonia.
It spreads rapidly, like the common cold. It has killed 4% of its known
victims, striking down not just the elderly and infirm but also
(occasionally) healthy adults. It is so new that no one is immune. And there
are no proven drugs for it.

Severe acute respiratory syndrome is a nightmare mix of virulence and
contagiousness. After simmering late last fall in Guangdong, China, the
viral disease exploded in Hong Kong and then spread rapidly to Vietnam,
Singapore, Canada, the U.S. and 14 other countries.

"Some viruses like Ebola kill people but don't spread easily. Others spread
readily but don't kill," says Anthony Fauci, director of the National
Institute of Allergy & Infectious Diseases. "This is extremely virulent, and
it spreads easily. It's a really bad combination."

The SARS outbreak is a stark reminder that for all our worry about
terrorists unleashing man-made germs, nature's own weapons factory is the
biggest threat of all. A few decades ago the medical establishment naively
figured that it could conquer infection with modern antibiotics and
vaccines. Fat chance. Microbes are constantly mutating and evolving into new
and deadly forms. Every few decades nature concocts a major new killer. HIV
was one of the last big ones. Only time will tell whether SARS is anywhere
near as threatening, but no one is ruling out the terrifying possibility.

"This is behaving in a way you might expect the next influenza pandemic to
begin. It is beyond one geographic region and has been spreading rapidly,"
says James Hughes, who heads the Center for Infectious Diseases at the
federal Centers for Disease Control & Prevention. His agency has assigned
250 scientists and statisticians to track and contain the epidemic,
determine how it spreads, devise a definitive diagnostic test and identify
its origins. Even if they can check the outbreak, he adds, "I suspect this
virus is here to stay."

SARS is so new that almost everything about it remains shrouded in
uncertainty. The disease starts with an achy fever that won't go away,
followed after a few days by a dry cough, pneumonia and shortness of breath.
About 90% of people recover on their own. But in about 10% of cases, lung
inflammation becomes so severe that a respirator is needed for breathing.
About a third of these patients die from massive respiratory failure.

The biggest unknown is how far and how fast it will spread. There are three
basic possibilities. The worst-case scenario is that the virus spreads like
wildfire to more and more countries until it becomes a full-blown global
epidemic, or pandemic. The SARS virus doesn't appear to spread as fast as
influenza. If it did, we'd have hundreds of thousands of cases by now.
Still, a killer bug that merely spreads as fast as a cold is horrifying
enough.

The best-case scenario is that the vigorous efforts to contain the virus
succeed and it quickly burns itself out in a few weeks or months. Already,
World Health Organization officials say, Vietnam and Singapore appear to be
getting the epidemic under control through quarantines and meticulous
hospital sanitation. The U.S. case count (under an expansive definition that
includes some uncertain cases) more than doubled between Mar. 31 and Apr. 7,
but almost all of these are people who traveled to Asia. Only a handful are
secondary cases originating in the U.S. from contact with these travelers.
And so far no one has died here.

The optimistic outcome, though, is unlikely. It is next to impossible to
eliminate a disease without a vaccine. That's why tuberculosis, AIDS and
malaria are still scourges of mankind. The most likely result is somewhere
between these two extremes: The disease stops short of global pandemic but
remains a smoldering threat--perhaps in rural China, perhaps in Africa,
perhaps throughout the globe--until we are able to finally develop a cheap
and effective vaccine, much like the ones for measles and the flu. But that
could easily take eight to ten years.

The prime suspect behind the disease is a new type of coronavirus that comes
from a well-known family of viruses responsible for up to 30% of cases of
the common cold, as well as various animal diseases. This strain appears to
have genetic similarities to human, cow and bird coronaviruses, according to
gene chip studies done at the University of California, San Francisco.
Coronaviruses are particularly good at grabbing and blending genetic
material from other species, says University of Southern California
coronavirus researcher Michael Lai. "We've always said [such a virulent
strain] was a possibility, but I never thought it would happen in my
lifetime," he says

Another possibility: All SARS cases, or all the life-threatening cases,
represent a dual infection with coronavirus and something else, such as a
novel metapneumovirus. Metapneumovirus has been found in some victims.

One mystery is how the virus is transmitted. The weight of the evidence so
far suggests that it spreads in a way similar to colds, either through the
coughing up of large droplets or through direct contact with patients or
objects the patient just touched and contaminated. Less likely but much more
alarming is the possibility that the virus, like a fine aerosol mist,
lingers in the air long after a sick person has coughed and gone. Influenza
and tuberculosis spread this way, making it next to impossible to stop the
chain of transmission.

Another mystery is why the disease has spread efficiently in some locales,
like Toronto, but not much at all in the U.S., despite a number of apparent
cases among returning travelers. One hypothesis is that some people may be
"supershedders" who spread huge amounts of viral particles. Or it may simply
be that the original victims in Hong Kong, Toronto and elsewhere didn't
arrive at the hospital until too late (if at all) and thus were able to
spread it to the highest number of people when the disease was at its most
infectious.

A race is now on to develop diagnostic tests for the syndrome, which has so
far been diagnosed by excluding other possibilities. The CDC has developed
two prototype antibody-based diagnostic tests and is rushing to validate
them. The CDC scientists have been working around the clock to sequence the
genome of the suspect coronavirus, and results are expected any day now. The
sequence could underpin a more definitive gene test for the virus; Roche
Diagnostics hopes to have one on the market within a couple months after the
sequence is ready.

Peter Jahrling, a virologist at the U.S. Army Medical Research Institute of
Infectious Diseases, has just began testing isolated bits of the coronavirus
against 2,000 approved drug compounds to see if any of them kill or disrupt
the virus. "We're going to be cranking these out at several hundred a day,"
he says. One of his first tests is to determine if the broad-spectrum
antiviral ribavirin, now used for viral hepatitis, is useful. Separately,
ViroPharma of Exton, Penn. says it plans to screen its entire
400,000-compound collection against the new coronavirus.

Dr. Fauci of the NIH has already convened a crash project to craft a dead
version of the coronavirus that would stimulate an immune response. But, he
says, "no matter how much I turn on the afterburners, I won't have a vaccine
ready for next winter."

http://www.forbes.com/forbes/2003/0428/047.html


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