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Influenza
(flu)
What is influenza (flu)?
Influenza or flu is a viral infection of the nose, throat, bronchial
tubes and lungs. There are two main types of virus: A and B. Each type
includes many different strains which tend to change each year.
When does influenza occur?
Influenza occurs most often in the winter months. Illnesses resembling
influenza may occur in the summer months but they are usually due to other
viruses.
Who gets influenza?
Anyone can get influenza, but it is most serious in the elderly, in
people with chronic underlying illnesses (such as cancer, emphysema or
diabetes) or those with weak immune systems.
How is it spread?
Influenza is highly contagious and is easily transmitted through contact
with droplets from the nose and throat of an infected person during coughing
and sneezing.
What are the symptoms of influenza?
Typical flu symptoms include headache, fever, chills, cough and body
aches. Intestinal symptoms are uncommon. Although most people are ill
for only a few days, some people have a much more serious illness, such
as pneumonia and may need to be hospitalized. Thousands of people die
each year in the United States from the flu or related complications.
How soon do symptoms appear?
The incubation period for influenza is one to five days.
How is influenza diagnosed?
Usually, a doctor will diagnose a case of the flu based on typical symptoms
of fever, chills, headache, cough and body aches. Specific lab tests to
confirm the flu are costly and time consuming and are usually limited
to outbreak or disease surveillance efforts.
When and for how long is a person able to spread influenza?
The contagious period varies, but probably begins the day before symptoms
appear and extends for a week. Does past infection with influenza make
a person immune?
Generally, no. The viruses that cause flu frequently change, so people
who have been infected or given a flu shot in previous years may become
infected with a new strain. Because of this, and because any immunity
produced by the flu shot will possibly decrease in the year after vaccination,
people in high-risk groups should be vaccinated every year.
What are the high-risk groups?
The following groups are at increased risk for serious illness with
the flu and should receive vaccine:
Others who should receive vaccine include household contacts of high-risk
people and health care workers who provide care to high-risk patients.
What is the treatment for influenza?
Rest and liquids are usually adequate. A prescription drug called amantadine
may prevent or reduce the severity of influenza type A, but is not effective
against type B.
What can be done to control or prevent influenza?
Routine immunization against influenza is the most important control
measure. Influenza vaccines may be available (flu shot) through your personal
physician or local health department. When influenza type A occurs, amantadine
may be prescribed for certain individuals. Because new influenza viruses
often appear, the effectiveness of the vaccine sometimes varies from one
year to the next. Nevertheless, studies have shown that even in years
when new strains emerge, people in high-risk groups who obtain annual
flu shots tend to have milder illness and are less likely to be hospitalized
with complications due to influenza A.
Source: NY State Department of Health
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