What Is influenza?

Influenza or "flu" is a respiratory disease caused by a virus. There are two main types of influenza virus - A and B. Each type includes many related viruses or strains, each slightly different from the others. Type A epidemics are generally more frequent and severe than those of type B.

How is influenza spread?

Influenza is spread from person to person when droplets of moisture from a person with influenza are spread through the air when that person coughs, sneezes or talks. These droplets contain viruses which can cause infection in susceptible people.

How soon do symptoms appear?

Typically one to three days after exposure.

How serious is influenza?

Influenza illness ranges from very mild to severe, depending on such factors as the influenza strain involved, and the person's susceptibility and general physical condition. Most people recover within a week although they may continue to feel weak for several days. Influenza can, however, last longer and cause life-threatening complications in high-risk individuals, the elderly, or in rare cases in normal, healthy individuals.

What are the symptoms of influenza?

Influenza symptoms include fever, chills, headache, dry cough, and soreness and aching in the back, arms, and legs. The risk of developing severe complications, such as pneumonia, and death increases with age (especially people over 55) or in individuals with chronic medical conditions (such as diabetes, diseases of the heart, lungs, or kidneys, severe anemia, or other chronic diseases that weaken the immune system including persons with AIDS or HIV infection).

How is influenza diagnosed and treated?

Usually the diagnosis is based on the appearance of classic signs and symptoms. Confirmation can be achieved in the lab by culturing throat specimens or by detecting antibodies in the patients blood samples. Two prescription drugs (amantadine, and rimantidine) are available for the treatment and prevention of influenza. These drugs may reduce the severity of influenza A if therapy is started early in the course of the illness. The drugs may also be used to prevent someone from developing influenza after an exposure or during an outbreak. Otherwise, bed rest, drinking more than the usual amount of liquids, and taking pain relievers to help reduce the discomfort of illness are recommended. Children with influenza should not be treated with aspirin.

Every year there seems to be a new strain of influenza going around, why?

The influenza viruses change frequently and therefore, from time to time, new strains of influenza virus appear. Epidemics then occur because people have not had previous exposure which would allow them to build specific immunity (protection) against the new strain.

How is influenza prevented?

There is a vaccine to protect against influenza. Because the influenza virus changes from year to year, it is important to get vaccinated against influenza on a yearly basis. In addition, flu shots are only protective for about a year.

Is the vaccine safe?

The vaccine is very safe and effective and generally has few side effects. There may be some soreness, redness or swelling where the shot is given. Other possible mild side effects include a headache and low-grade fever for a day after the vaccination. However, in general the benefits of being vaccinated far outweigh the risks. You cannot get influenza from the vaccine.

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