Influenza

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VOL 114 / NO 5 / NOVEMBER 2003 / POSTGRADUATE MEDICINE

You woke up tired and have a sore throat, headache, and fever. You didn't think it was possible to feel this achy. You have influenza, commonly known as the flu, a viral disease that is spread from person to person. In the United States, flu season occurs in the winter, when cold, dry weather allows the influenza virus to thrive outside the body and at the same time forces people indoors, increasing the risk of exposure to the virus. During this season, as many as 20% of people get the flu.

What is the flu?
When you get the flu, a virus infects your nose, throat, and airways, which become swollen and inflamed. Symptoms appear within about 1 to 4 days. Most people begin to feel better after a few days, but people who are elderly or who weren't healthy to begin with can become very ill. In these people, the flu can lead to pneumonia or even death.

Two types of influenza are currently circulating: A and B. Type A has two subtypes, which have different symptoms. There is also a type C, but it causes only mild illness and does not spread as easily as types A and B. You can have the flu more than once a year, because different viruses are always going around, and they can change from year to year.

What are the symptoms?
The flu can cause a fever, chills, aches, a sore throat, a dry cough, weakness, fatigue, loss of appetite, nausea, a runny nose, and burning eyes.

Is there any treatment for the flu?
Your doctor may do a test to see which kind of flu you have and may choose to give you an antiviral medication to shorten your illness by 1 or 2 days. Antibiotics, which kill bacteria, cannot kill viruses and thus are not used to treat the flu.

Generally, you should rest and drink lots of fluids. Both adults and children can take medications such as acetaminophen or ibuprofen for the fever, aches, and pains of the flu. However, never give aspirin to children or teenagers who have symptoms of the flu without first calling your doctor. In young people, aspirin can cause a serious illness called Reye's syndrome. To avoid spreading the flu, which you can do from the day before you get symptoms to about a week later, it is best to stay home.

How can I avoid getting the flu?
The flu virus is usually spread through droplets that are in the air as a result of coughing, sneezing, and talking, but you can be infected by touching objects such as a door handle that someone with the flu has touched. Washing your hands often, keeping them away from your nose and mouth, and staying away from people who have the flu are good ways to protect yourself.

Many people opt to get the flu shot, or influenza vaccine, which prevents some kinds of the flu. The vaccine is made differently each year to fight off the viruses that are expected to be a problem that year. You cannot get the flu from the vaccine. It works by causing the body to make substances called antibodies, which help protect against the viruses.

People considered at high risk for the flu should receive the vaccine each year. This group includes people over age 50, those who live in a nursing home, healthcare professionals, and people who have chronic lung disease (for example, asthma, emphysema, cystic fibrosis, tuberculosis, or chronic bronchitis), heart or kidney disease, diabetes, severe anemia, or cancer.

The best time to receive the influenza vaccine is between October 15 and November 15, because it takes about 2 weeks for the vaccine to begin to work. However, you can get the shot earlier or at any time during the flu season. Most people have no reaction to the vaccine, but about one in four people has redness and swelling in the area where the shot was given. A smaller number also have a fever, chills, a headache, and body aches for a few days.

People who are allergic to eggs should not get the vaccination unless it is recommended by their doctor and given under the doctor's supervision. These precautions are necessary because the vaccine virus is grown in eggs, which cannot be completely eliminated from the vaccine.

Medicare and some health insurance plans pay for the influenza vaccination; check with your carrier to make sure it covers the cost.

Antiviral drugs also can be given to prevent the flu, but they can cause side effects (for example, trouble sleeping, shakiness, or depression). One antiviral drug has been known to worsen asthma in some people.

For more information on the flu:

American Lung Association
61 Broadway, 6th floor
New York, NY 10006
212-315-8700
http://www.lungusa.org/diseases/luninfluenz.shtml

Centers for Disease Control and Prevention
http://www.cdc.gov/ncidod/diseases/flu/fluinfo.shtml

MEDLINEplus, National Library of Medicine
National Institutes of Health
http://www.nlm.nih.gov/medlineplus/influenza.shtml

World Health Organization
http://www.who.int/health_topics/influenza/en

This information is not a substitute for medical treatment.

Please send technical questions related to the Web site to Ann Harste