Influenza
(the flu) Questions & Answers
| The
Disease of Influenza (the flu) |
|
What
is influenza (the flu)?
 |
| Influenza
Viruses |
Influenza,
commonly called "the flu," is caused by the influenza
virus, which infects the respiratory tract (nose, throat,
lungs). The flu usually spreads from person to person when an
infected person coughs, sneezes, or talks and the virus is sent
into the air. Unlike many other viral respiratory infections,
such as the common cold, the flu causes severe illness and
life-threatening complications in many people.
What
are the symptoms of the flu?
Influenza
is a respiratory illness. Symptoms of flu include fever,
headache, extreme tiredness, dry cough, sore throat, runny or
stuffy nose, and muscle aches. Children can have additional
gastro-intestinal symptoms, such as nausea, vomiting, and
diarrhea, but these symptoms are uncommon in adults. Although
the term "stomach flu" is sometimes used to describe
vomiting, nausea, or diarrhea, these illnesses are caused by
certain other viruses, bacteria, or possibly parasites, and are
rarely related to influenza.
Does
the flu have complications?
Yes. Some
of the complications caused by flu include bacterial pneumonia,
dehydration, and worsening of chronic medical conditions, such
as congestive heart failure, asthma, or diabetes. Children may
get sinus problems and ear infections as complications from the
flu. Those aged 65 years and older and persons of any age
with chronic medical conditions are at highest risk for serious
complications of flu.
How
do I find out if I have the flu?
It
is very difficult to distinguish the flu from other viral or
bacterial causes of respiratory illnesses on the basis of
symptoms alone. A test can confirm that an illness is influenza
if the patient is tested within the first two to three days
after symptoms begin. In addition, a doctor’s examination may
be needed to determine whether a person has another infection
that is a complication of influenza.
How
soon will I get sick if I am exposed to the flu?
The
time from when a person is exposed to flu virus to when symptoms
begin is about one to four days, with an average of about two
days.
How
long is a person with flu virus contagious?
The
period when an infected person is contagious depends on the age
of the person. Adults may be contagious from one day prior
to becoming sick and for three to seven days after they first
develop symptoms. Some children may be contagious for longer
than a week.
| Preventing
and Treating the Flu |
|
What
can I do to protect myself against the flu?
 |
|
A
Flu Shot Can
Prevent Flu
|
By
far, the single best way to prevent the flu is for individuals,
especially persons at high risk for serious complications from
the flu, to get a flu shot each fall.
Who
should get a flu shot?
The
most important groups
of persons who should get flu shots are those who are at highest
risk for developing serious complications from the flu.
See:
Who Should Get A Flu Shot
Can
antiviral drugs cure the flu?
Not
exactly. When started within the first two days of
illness, they can reduce the duration of the disease but cannot
cure it outright.
Four
different antiviral drugs (amantadine, rimantadine, zanamivir,
and oseltamivir) have been approved for treating the flu. All
four drugs can reduce the duration of flu by about one day if
taken within 2 days of when symptoms begin. The four drugs
differ in terms of side effects. In some patients, amantadine (Symmetrel®,
others) can cause symptoms such as nervousness, difficulty
concentrating, or lightheadedness. Rimantadine (Flumadine®) can
also cause similar types of side effects, but less often.
Caution is advised if zanamivir (Relenza®) is used by people
who have asthma or chronic obstructive pulmonary disease,
because the airways of these people may suddenly grow
smaller after using zanamivir, leading to difficulty breathing.
Oseltamivir (Tamiflu®) can cause nausea and vomiting in some
people.
All
of these drugs must be prescribed by a doctor. These drugs are
effective against flu viruses, but they are not effective
against other viruses or bacteria that can cause symptoms
similar to influenza. These drugs are not effective for treating
bacterial infections that can occur as complications of
influenza.
Can
antiviral medications prevent the flu?
Three
of the antiviral drugs (amantadine, rimantadine, and oseltamivir)
have been approved for prevention of the flu. These drugs are
not, however, a substitute for influenza vaccination. All of
these drugs are prescription drugs, and a doctor should be
consulted before the drugs are used for preventing the flu.
For
More Information About Influenza Antiviral Drugs:
"Prevention
and Control of Influenza, Recommendations of the Advisory
Committee on Immunization Practices (ACIP)," Morbidity
and Mortality Weekly Report (MMWR), April 25, 2003/ Vol. 52
/ No. RR-08.
| When
You Are Most Likely to Get the Flu |
|
When
is the flu season in the United States?
In
the United States, the peak of flu season can occur anywhere
from late December through March. The health impact
(infections and deaths) of a flu season varies from year to
year. CDC monitors circulating flu viruses and their related
disease activity and provides influenza reports each week from
October through May. See: Weekly
U.S. Flu Report
How
many people get sick or die from the flu every year?
 |
|
500,000
Americans Died
in 1918 From the Flu
|
Each
flu season is unique, but it is estimated that approximately 10%
to 20% of U.S. residents get the flu, and an average of 114,000
persons are hospitalized for flu-related complications. About
36,000 Americans die on average per year from the complications
of flu.
Do
other respiratory viruses circulate during the flu season?
In
addition to the flu virus, several other respiratory viruses
also can circulate during the flu season and can cause symptoms
and illness similar to those seen with flu infection. These
non-flu viruses include rhinovirus (one cause of the “common
cold”) and respiratory
syncytial virus (RSV), which is the most common cause of
severe respiratory illness in young children as well as a
leading cause of death from respiratory illness in those aged 65
years and older.
What
are some of the myths about flu?
There
are several common myths about flu, including:
Myth
#1:
Influenza is merely a nuisance. |
Wrong.
Influenza is a major cause of illness and death in the
United States and leads to an average of about 36,000
deaths and 114,000 hospitalizations per year. |
Myth
#2:
Flu shots cause the flu. |
Wrong.
The licensed injectable flu vaccine used in the United
States, which is made from inactivated or killed
flu viruses, cannot cause the flu and does not cause flu
illness. |
Myth
#3:
Flu vaccine doesn’t work. |
Not
exactly. When the viruses in the vaccine and
circulating viruses are similar, the flu shot is very
effective. There are several reasons why people think
influenza vaccine doesn't work. People who have gotten a
flu vaccination may then get sick from a different virus
that causes respiratory illness but is mistaken for flu;
the flu shot only prevents illness caused by the
influenza virus. In addition, protection from the
vaccine is not 100%. Studies of healthy young adults
have shown flu vaccine to be 70% to 90% effective in
preventing the flu. In the elderly and those with
certain long-term medical conditions, the flu shot is
often less effective in preventing illness. However, in
the elderly, flu vaccine is very effective in reducing
hospitalizations and death from flu-related causes.
|
Myth
#4:
There is no need to get a flu vaccine every year.
|
Wrong.
The flu viruses are constantly changing.
Generally, new influenza virus strains circulate every
flu season, so the vaccine is changed each year. |
|
