Influenza, also known as “the flu,” is a virus that infects the respiratory
tract. Although Influenza is not as severe as many viral infections it\'s
almost the worst for viral infections of the respiratory tract. Typically, when
someone is infected with influenza they experience fever (usually 100° to 103°F
in adults, but even higher in children) and causes a cough, sore throat, runny
or stuffy nose, and also headaches, muscle aches, and usually extreme tiredness.
There are sometimes other symptoms such as nausea, vomiting and diarrhea but
usually only in rare cases with young children. One other note: The term
“Stomach flu” isn’t really caused by the influenza virus.
The average recovery time from the flu is about 1-2 weeks, although some
patients do develop more severe complications such as pneumonia, which are
capable of being life threatening. On average, influenza is associated with
more than 20,000 deaths nationwide and more than 100,000 hospitalizations. These
are usually from patients who develop complications and they are usually
children or the elderly, although complications can develop at any age.
There are three types of influenza viruses, Groups A, B, and C. Only Groups A
and B are responsible for causing the epidemics of flu that occur almost every
year. Influenza C is different in several ways because it causes mild to no
symptoms and doesn’t cause the yearly epidemics. Scientists put out most of
their effort to control influenza A and B because of their huge impact on the
nation and the world. Influenza type A viruses have two proteins that determine
their specific type. Take Influenza A(H1N1) the H stands for hemagglutinin and
the N stands for neuraminidase. The current types of Influenza A are A(H1N1)
and A(H3N2). Influenza A(H1N1), A(H3N2), and Influenza B strains are included
in each year’s vaccines.
Influenza A viruses are very hard to control because they undergo changes,
making it harder for human’s immune systems to detect them. There are two types
of changes. The first is a series of mutations that occur over time and cause a
gradual change in the virus. This is called antigenic “drift.” This process
allows the virus to make a more stable change yet still evade the immune
system. The second type of change is an abrupt change in the hemagglutinin
and/or the neuraminidase proteins. This is called antigenic \"shift.” It
isn’t as stable of a change but if it does make a successful and complete
mutation it can become so deadly that another pandemic. Although Type A viruses
undergo both types of changes, Type B only go through the more gradual Type B.
Antigenic shift occurs only occasionally, but when it does large numbers of
people or even entire populations have no antibody against the virus. Although
this is potentially lethal, the virus can only start a pandemic if it is able
to be spread easily. Throughout the 20th century there were three pandemics,
one in 1918, one in 1957, and one in 1968. Each of which resulted in large
numbers of deaths.
The 1918 pandemic was known as the “Spanish Flu” and was Influenza strain
A(H1N1) and it caused the highest known influenza death rate known, 500,000
Americans and 20 million people worldwide.
The 1957 pandemic was known as the “Asian Flu” and was Influenza strain A(H2N2)
and caused 70,000 U.S. deaths.
The 1968 Pandemic was known as the “Hong Kong Flu” and was Influenza strain
A(H3N2) and caused 34,000 deaths in the U.S.
The emergence of the “Hong Kong Flu” in 1968-1969 marked the beginning of the
A(H3N2) days. When this virus first emerged it had the lowest mortality rate in
the 20th century. Although this virus first emerged with such a small death
rate, it still continues to kill people to this day. Just as when the A(H2N2)
virus appeared in 1957 causing the disappearance of the A(H1N1) virus, the
appearance of the A(H2N3) virus caused the disappearance of the A(H2N2) virus.
After being dormant for almost 30 years, the A(H1N1) virus reappeared and today
the A(H1N1) virus and A(H2N3) viruses co-circulate each year along with a few
different strains of Influenza Type B.
Now, to answer a few common questions about influenza.
Q. If I am exposed to a person with Influenza and become infected, how soon
will I get sick? Also, how long is a person contagious with Influenza?
A. The time between infection and appearance of symptoms (incubation period)
for influenza can range between 1 and 4 days. A person with influenza can be
contagious 1 day before symptoms appear and for 3 to 7 days after onset of
symptoms. Children can be contagious for longer than 7 days.
Q. Can I be vaccinated against pneumonia, the complication of influenza
infection?
A. A vaccine is available to prevent some types of pneumonia, especially those
caused by bacteria in the “pneumococcus” family. You should be vaccinated if
you are in a group for which the vaccine is recommended. These groups are
usually about the same as the groups that are recommended for the Influenza
vaccine.
Q. I would like to receive an influenza vaccine but how effective are they
really?
A. In the years when there is a good match between the vaccine virus and the
virus strain causing illness, influenza vaccine is generally considered to be
70% to 90% effective in preventing influenza illness in healthy adults. Influenza
vaccine is quite a bit less effective in preventing respiratory illness in the
elderly, but is still about 50% to 80% effective at preventing complications
from influenza infection. It is very important to know that for a person to
develop protection against infection. (One additional note: Influenza vaccine
does not protect against respiratory illness caused by other viruses.)
Q. Is the Influenza vaccine safe? If so what are the side effects if any?
A. The Influenza vaccine in “Most” cases is safe. People with severe allergic
reactions to eggs should not receive Influenza vaccines, since the vaccine is
prepared from influenza grown in eggs. The most common side effect is mild
soreness at the injection site. Serious side effects such as such as life-threatening
allergic reactions or Guilain-Barre syndrome are rare (fewer than 1to 2 cases
per million vaccine recipients).
Although the virus will continue to change and we will continue to try to
defeat it, we never will. Just in the past three years two new strains have
been discovered but were isolated and wiped out quickly. Maybe next time we
won’t be so lucky but maybe we will. After all, it’s only the flu and humans
didn’t get this far by worrying about it.
Works Cited (I did it in MLA Format so be happy):P
References:
“Influenza A(H5N1).” Who.gov. Online. January, 1998.
“Isolation of Avian Influenza A(H5N10 Viruses from Humans.” CDC.Gov. Online.
Hong Kong, May-December, 1997.
Larson, Erik. “The Flu Hunters.” TIME. February 23, 1998. Britannica.com.
Simao, Paul. “Flu Season.” Rueters. Thursday March 22, 2001. Britannica.com.
Stannard, Linda M. “Influenza Virus.” 1995. Uct.ac.za.
By
Grant Wade
April 22, 2001
Fayetteville, Arkansas
Email me at Buzbom99@aol.com if you use this paper please.