I was really curious as to why we are freaking out about 190 confirmed cases when there are 300 million people in the U.S. Compared to the average winter flu, that is a drop in the bucket... there is some evidence out there that this virus was produced as a biological weapon, much like the H5N1 virus (avian flu), but that is conjecture at the moment.
Thought you all might find this interesting.
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Scientists see this flu strain as relatively mild
Genetic data indicate this outbreak won't be as deadly as that of
1918, or even the average winter.
By Karen Kaplan and Alan Zarembo
April 30, 2009
As the World Health Organization raised its infectious disease alert
level Wednesday and health officials confirmed the first death linked
to swine flu inside U.S. borders, scientists studying the virus are
coming to the consensus that this hybrid strain of influenza -- at
least in its current form -- isn't shaping up to be as fatal as the
strains that caused some previous pandemics.
In fact, the current outbreak of the H1N1 virus, which emerged in San
Diego and southern Mexico late last month, may not even do as much
damage as the run-of-the-mill flu outbreaks that occur each winter
without much fanfare.
"Let's not lose track of the fact that the normal seasonal influenza
is a huge public health problem that kills tens of thousands of
people in the U.S. alone and hundreds of thousands around the world,"
said Dr. Christopher Olsen, a molecular virologist who studies swine
flu at the University of Wisconsin School of Veterinary Medicine in Madison.
His remarks Wednesday came the same day Texas authorities announced
that a nearly 2-year-old boy with the virus had died in a Houston
hospital Monday.
"Any time someone dies, it's heartbreaking for their families and
friends," Olsen said. "But we do need to keep this in perspective."
Flu viruses are known to be notoriously unpredictable, and this
strain could mutate at any point -- becoming either more benign or
dangerously severe. But mounting preliminary evidence from genetics
labs, epidemiology models and simple mathematics suggests that the
worst-case scenarios are likely to be avoided in the current outbreak.
"This virus doesn't have anywhere near the capacity to kill like the
1918 virus," which claimed an estimated 50 million victims worldwide,
said Richard Webby, a leading influenza virologist at St. Jude
Children's Research Hospital in Memphis, Tenn.
When the current virus was first identified, the similarities between
it and the 1918 flu seemed ominous.
Both arose in the spring at the tail end of the flu season. Both
seemed to strike people who were young and healthy instead of the
elderly and infants. Both were H1N1 strains, so called because they
had the same types of two key proteins that are largely responsible
for a virus' ability to infect and spread.
The Centers for Disease Control and Prevention and the National
Institutes of Health published genetic sequence data Monday morning
of flu samples isolated from patients in California and Texas, and
thousands of scientists immediately began downloading the
information. Comparisons to known killers -- such as the 1918 strain
and the highly lethal H5N1 avian virus -- have since provided welcome news.
"There are certain characteristics, molecular signatures, which this
virus lacks," said Peter Palese, a microbiologist and influenza
expert at Mt. Sinai Medical Center in New York. In particular, the
swine flu lacks an amino acid that appears to increase the number of
virus particles in the lungs and make the disease more deadly.
Scientists have identified several other differences between the
current virus and its 1918 predecessor, but the significance of those
differences is still unclear, said Dr. Scott Layne, an epidemiologist
at the UCLA School of Public Health.
Ralph Tripp, an influenza expert at the University of Georgia, said
that his early analysis of the virus' protein-making instructions
suggested that people exposed to the 1957 flu pandemic -- which
killed up to 2 million people worldwide -- may have some immunity to
the new strain.
That could explain why older people have been spared in Mexico, where
the swine flu has been most deadly.
The swine virus does appear able to spread easily among humans, which
persuaded the WHO to boost its influenza pandemic alert level to
phase 5, indicating that a worldwide outbreak of infection is very
likely. And the CDC reported on its website that "a pattern of more
severe illness associated with the virus may be emerging in the United States."
"We expect to see more cases, more hospitalizations, and,
unfortunately, we are likely to see more deaths from the outbreak,"
Health and Human Services Secretary Kathleen Sebelius told reporters
Wednesday on her first day at work.
But certainly nothing that would dwarf a typical flu season. In the
U.S., between 5% and 20% of the population becomes ill and 36,000
people die -- a mortality rate of between 0.24% and 0.96%.
Dirk Brockmann, a professor of engineering and applied mathematics at
Northwestern University in Evanston, Ill., used a computer model of
human travel patterns to predict how this swine flu virus would
spread in the worst-case scenario, in which nothing is done to
contain the disease.
After four weeks, almost 1,700 people in the U.S. would have
symptoms, including 198 in Los Angeles, according to his model.
That's just a fraction of the county's thousands of yearly flu victims.
Just because the virus is being identified in a growing number of
places -- including Austria, Canada, Germany, Israel, New Zealand,
Spain and Britain -- doesn't mean it's spreading particularly
quickly, Olsen said.
"You don't ever find anything that you don't look for," he said. "Now
that diagnostic laboratories and physicians and other healthcare
workers know to look for it, perhaps it's not surprising that you're
going to see additional cases identified."
And a pandemic doesn't necessarily have a high fatality rate. Even in
Mexico, the fatalities may simply reflect that hundreds of thousands
of people have been infected. Since the symptoms of swine flu are
identical to those of a normal flu, there's no way to know how many
cases have evaded government health officials, St. Jude's Webby said.
As the virus adapts to its human hosts, it is likely to find ways of
spreading more efficiently. But evolution also suggests it might
become less dangerous, Olsen said.
"If it kills off all its potential hosts, you reach a point where the
virus can't survive," he said. Working to calm public fears, U.S.
officials on Wednesday repeatedly stressed the statistic of yearly
flu deaths -- 36,000.
Sebelius and Homeland Security Secretary Janet Napolitano also
rejected calls to close the borders, which several lawmakers
reiterated Wednesday on Capitol Hill.
"We are making all of our decisions based on the science and the
epidemiology," Napolitano said. "The CDC, the public health community
and the World Health Organization all have said that closing out
nation's borders is not merited here."
Though scientists have begun to relax about the initial toll, they're
considerably less comfortable when taking into account the fall flu
season. They remain haunted by the experience of 1918, when the
relatively mild first wave of flu was followed several months later
by a more aggressive wave.
The longer the virus survives, the more chances it has to mutate into
a deadlier form.
"If this virus keep going through our summer," Palese said, "I would
be very concerned."
Staff writers Noam Levey in Washington, Thomas H. Maugh II in Los
Angeles and Ken Ellingwood in Mexico City contributed to this report.
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