Influenza, commonly called "the flu," is an infection of the respiratory tract caused by the influenza virus. Compared with most viral respiratory infections, such as the common cold, influenza infection often causes a more severe illness. Typical influenza illness includes fever (usually 100 degrees F to 103 degrees F in adults and often even higher in children) and respiratory symptoms, such as cough, sore throat, runny or stuffy nose, as well as headache, muscle aches and extreme fatigue. Although nausea, vomiting and diarrhea can sometimes accompany influenza infection, especially in children, these symptoms are rarely the primary symptoms. The term "stomach flu" is a misnomer that is sometimes used to describe gastrointestinal illnesses caused by organisms other than influenza viruses.
Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. Over the past decade, influenza and pneumonia have been associated with an average of 3,500 deaths a year in Illinois. Since 1992, the highest number of flu and pneumonia deaths was the 4,021 recorded in 1993. Flu-related complications can occur at any age, but the elderly and people with chronic health problems are much more likely to develop serious complications after influenza infection than are young, healthier people. During most flu seasons, which typically run from November to April, between 10 percent and 20 percent of the population is infected with influenza viruses. More than 200,000 people are hospitalized from flu complications each year in the U. S.
Influenza Viruses
Influenza viruses are divided into three types, designated A, B and C. Influenza types A and B are responsible for epidemics of respiratory illness that occur almost every winter and are often associated with increased rates for hospitalization and death. Influenza type C differs from types A and B in some important ways. Type C infection usually causes either a very mild respiratory illness or no symptoms at all. It does not cause epidemics and does not have the severe public health impact that influenza types A and B do. Efforts to control the impact of influenza are aimed at types A and B.
The 2010–11 trivalent vaccines contain A/California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-like, and B/Brisbane/60/2008-like antigens. The influenza A (H1N1) vaccine virus is derived from a 2009 pandemic influenza A (H1N1) virus.
Above information taken from http://www.idph.state.il.us/flu/index.htm
Symptoms of
flu
People who have the flu often feel some or all of these symptoms:
•fever* or
feeling feverish/chills
•cough
•sore throat
•runny or stuffy nose
•muscle or body aches
•headaches
•fatigue (very tired)
•Some people may have vomiting and diarrhea, though this is more common in
children than adults.
*It’s important to note that not everyone with flu will have a fever.
How flu
spreads
Most experts believe that flu viruses spread mainly by
droplets made when people with flu cough, sneeze or talk. These droplets can
land in the mouths or noses of people who are nearby. Less often, a person
might also get flu by touching a surface or object that has flu virus on it and
then touching their own mouth, eyes or nose.
Period of contagiousness
You may be able to
pass on the flu to someone else before you know you are sick, as well as while
you are sick. Most healthy adults may be able to infect others beginning 1 day
before symptoms develop and up to 5-7 days after becoming sick. Some people,
especially children and people with weakened immune systems, might be able to
infect others for an even longer time.
How serious
is the flu?
Flu is unpredictable and how severe it is can vary widely from one season to
the next depending on many things, including:
•what flu
viruses are spreading,
•how much flu vaccine is available
•when vaccine is available
•how many people get vaccinated, and
•how well the flu vaccine is matched to flu viruses that are causing illness.
Certain people are at greater risk for serious complications if they get the
flu. This includes older people, young children, pregnant women and people with
certain health conditions (such as asthma, diabetes, or heart disease).
Above information taken directly from CDC.gov
Additional Online Resources:
Centers for Disease Control and Prevention
http://www.cdc.gov/flu/about/disease/high_risk.htm
Illinois Department of Public Health: Flu activity
http://www.idph.state.il.us/flu/fluupdate10-11.htm
Flu.gov
Google flu trends
http://www.google.org/flutrends/
National Institutes of Health
http://www.nlm.nih.gov/medlineplus/flu.html