The whole world is talking about swine flu as scientists scramble to
learn more about this emerging disease. Outbreaks of this infectious
new strain of influenza virus have proved deadly in some places,
relatively benign in others. Some people are avoiding travel to
infected areas. Others wonder about a possible vaccine.
Influenza has been with us for a long time. In ancient Greece, Hippocrates described it 2,500 years ago.
In
the 20th century, a worldwide epidemic - a pandemic - known as the
Spanish flu killed tens of millions, though the same virus today might
not be as deadly because medical care is so much better.
Another
flu pandemic emerged in 1957. It was known as the Asian flu and killed
an estimated one million people. A third but less serious pandemic, the
Hong Kong flu, broke out in 1968.
Swine flu first came to
widespread attention in 1976 after an outbreak in the United States.
Health officials ordered mass vaccinations, fearing a repeat of the
1918 pandemic, but the disease never reached that level.
The new
swine flu virus is actually a genetic mashup, containing bits of human
and bird flu, as well as a variety that infects pigs.
"Well,
in some ways the term 'swine flu' is a misnomer," says Dr. Gregory
Gray, who heads the Center for Emerging Infectious Diseases at the
University of Iowa.
"This particular strain of influenza may
have components of swine influenza," Gray adds, "but it's acting more
like a traditional annual influenza that we see every year."
Mexico
seems to be the place where this swine flu first infected large numbers
of people. Dr. Joan Nichols, an influenza researcher at the University
of Texas and the Galveston National Laboratory, says the new viral
strain found the right conditions to emerge.
"In this case, if
it's a swine virus, it came out of a population where you had a lot of
rural communities, pig farms in close proximity to either wild birds or
domestic bird populations to get the avian mix into it," Nichols says.
"Anywhere you have animals and agricultural settings, you have people
in close proximity working with them. So in terms of the agricultural
side, I mean, that's the side that would allow for transmission."
Reflecting
heightened concerns that international outbreaks of the swine flu could
accelerate, the World Health Organization has increased its global
alert status, and some governments are discouraging travel to affected
areas. But Dr. Keiji Fukuda, the WHO's assistant director-general, said
on Monday that there is little point in imposing travel bans
"predominantly because this virus has already spread quite far and at
this time, containment is not a feasible operation."
Experts say
the influenza can be spread from person to person in several ways - by
droplets in the air from sneezing without covering your mouth and nose,
or from kissing, or from touching contaminated surfaces. But despite
the name, they say you can't get swine flu from eating properly cooked
pork products.
So far the disease has been much more severe in
Mexico than in any other country - more cases there, and more serious
ones. The acting head of the CDC - the U.S. Centers for Disease Control
and Prevention - says the reason for that is still unclear.
"That
is a critical question," says Dr. Richard Besser. "What we need to
understand is why we're seeing a different disease spectrum in Mexico
than we're seeing here. There are many reasons that could explain that,
and as we gather information, we hope to sort that out. As we continue
to look, I expect that we will see additional cases, and I expect that
the spectrum of disease will expand."
Swine flu can only be
identified definitively by laboratory tests. Dr. Joe Bresee of CDC's
Influenza Division says swine flu symptoms are not very distinctive.
"Symptoms
are similar to the symptoms of regular human flu and can include fever,
cough, sore throat, body aches, headache, chills or fatigue. Some
people with swine flu have also reported diarrhea or vomiting. Like
seasonal flu, swine flu may cause a worsening of underlying chronic
medical conditions."
That's from one of the informative podcasts CDC is producing to get out information about swine flu.
The
CDC is laying the groundwork for the possible production of a swine flu
vaccine, though it would be months before large quantities could be
produced. The annual flu vaccine may provide some protection, and Joan
Nichols of the University of Texas says antiviral drugs may also be
helpful.
"We're also lucky in this case that the virus is
sensitive to some of the drugs that we use to treat influenza. And
that's a really good thing. That drug is ready immediately, and a
number of countries, including the U.S., have stockpiled these drugs."
Whatever
the situation now, it's likely to change in the coming days, weeks and
months as scientists and public health officials continue to monitor
this emerging disease . They're hopeful that it will run its course
quickly, but mindful, too, of influenza's notorious past.
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