What is Influenza (the flu)?
Influenza (the flu) is a contagious disease that is caused by 3
viruses, influenza A, B and C. It attacks the respiratory tract
(nose, throat, and lungs). Type A is usually responsible for the
large outbreaks and is a constantly changing virus. New strains
of Type A develop regularly and cause new epidemics every few years.
Type B causes smaller outbreaks, and Type C usually causes mild
illness. The flu is different from a cold. While both are caused
by viruses, high fever, headaches and extreme exhaustion are much
more common with the flu. The flu can also cause serious complications
such as bronchitis and pneumonia for certain high-risk groups.
Is it common?
Millions of people in the U.S. - about 10% to 20% of the population
- will get the flu each year. Most people who get the flu will recover
in 1 to 2 weeks, but some people will develop life-threatening complications
(such as pneumonia) as a result of the flu. An average of about
20,000 people per year in the U.S. die from the flu, and 114,000
per year have to be admitted to the hospital as a result of influenza.
How is the influenza virus
transmitted?
The flu is transmitted when a person who has the flu coughs, sneezes,
or speaks and sends the flu virus into the air, and other people
inhale the virus. The virus enters the nose, throat, or lungs and
begins to multiply, causing flu symptoms. Less often, the flu may
be spread when a person touches a surface that has flu viruses on
it, such as a doorknob, and then touches their nose or mouth.
What are the symptoms?
The flu usually comes on suddenly and may include these symptoms:
Fever
Headache
Tiredness (can be extreme)
Dry cough
Sore throat
Nasal congestion
Body aches
Loss of appetite
These symptoms are usually referred to as "flu-like symptoms."
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).
People of any age with chronic medical conditions, people over
65 years old and very young children are more likely to get complications
from the flu. Pneumonia, bronchitis, and sinus and ear infections
are three examples of complications from the flu. The flu can make
chronic health problems worse. For example, people with asthma may
experience asthma attacks while they have the flu, and people with
chronic congestive heart failure may have worsening of this condition.
Is the flu contagious?
A person can spread the flu starting 1 day before they feel sick.
Adults can continue to pass the flu virus to others for another
3 to 7 days after symptoms start. Children can pass the virus for
longer than 7 days. Symptoms start 1 to 4 days after the virus enters
the body. Some people can be infected with the flu virus but have
no symptoms. During this time, those people can still spread the
virus to others.
How is it diagnosed?
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 2 to 3 days after symptoms begin. In
addition, a medical provider's exam may be needed to determine whether
a person has another infection that is a complication of the flu.
How is it treated?
For mild flu in people who are not high risk (people who do not
have chronic medical conditions, HIV, asthma or anemia), the following
is the most common treatment:
Rest
Drink plenty of liquids
Avoid using alcohol and tobacco
Take pain medication (such as Advil or Tylenol) to relieve the
symptoms of flu. Do NOT take aspirin because it can cause Reye
syndrome, a rare but serious illness in teenagers and children.
Influenza is caused by a virus, so antibiotics don't work to cure
it. The best way to prevent the flu is to get an influenza vaccine
(flu shot) each fall, before flu season.
If the flu is diagnosed within 48 hours of the onset of symptoms,
several antiviral medications are available for people in high-risk
groups. These medications may shorten the duration of symptoms by
approximately 1 day. They must be prescribed by a medical provider
and may have side effects.
What about the "stomach
flu?"
Many people use the term "stomach flu" to describe illnesses
with nausea, vomiting, or diarrhea that are not caused by the flu
virus, but can be caused by many different viruses, bacteria, or
even parasites. However, while vomiting, diarrhea, and being "sick
to your stomach" can sometimes be related to the flu - particularly
in children - these problems are rarely the main symptoms of influenza.
The flu is a respiratory disease and not a stomach or intestinal
disease. Learn more about the stomach flu (viral gastroenteritis) here.
When is the flu season in the
U.S.?
In the U.S., the peak of flu season can occur anywhere from late
December through March.
Who should get a flu shot?
Anyone can get the flu (even healthy people), and serious problems
from flu can happen at any age. We usually recommend that college
students get a flu shot because it is easily spread in residence
halls and other typical college settings. Other groups that should
usually be vaccinated include:
People with chronic disorders, including diabetes and asthma
People with kidney problems, anemia or immunosuppression (such
as HIV)
People planning to travel out of the country during the winter
Health care workers and students working in health care or child
care
Who should NOT get a flu shot?
The following groups should not get a flu shot before talking with
their doctor:
People who are have a severe allergy to eggs or thimerosal (a
medication preservative)
People who have had a severe reaction to a flu shot in the past
People who previously developed Guillain-Barre syndrome (a disease
which causes nerve damage) in the 6 weeks after getting a flu
shot
If you are sick, have an acute respiratory infection or have
a fever, you should delay getting the flu shot until your symptoms
are gone.
Can I get a flu shot at Brown? Every Fall, Health Services sponsors flu clinics for the Brown community. Please watch Morning Mail and other advertisements for the upcoming clinics.
Links you can use
The majority of the information on this page is taken from this
site.
This site has several articles on influenza, including the latest
news, general overviews and diagrams.
Is it a cold or the flu? Familydoctor.org will help you sort through
common symptoms to know the differences between a cold and the flu
and when you should see a medical provider.
Disclaimer: Health Education is part of Health Services at Brown University. Health Education maintains this site as a resource for Brown students. This site is not intended to replace consultation with your medical providers. No site can replace real conversation. Health Education offers no endorsement of and assumes no liability for the currency, accuracy, or availability of the information on the sites we link to or the care provided by the resources listed. Health Services staff are available to treat and give medical advice to Brown University students only. If you are not a Brown student, but are in need of medical assistance please call your own health care provider or in case of an emergency, dial 911. Please contact us if you have comments, questions or suggestions.
