Influenza, also called the "flu," is a highly contagious respiratory infection.

Flu can cause fever, chills, headache, dry cough, runny or stuffy nose, sore throat, and muscle aches. Unlike other common respiratory infections, such as the common cold, influenza can cause extreme fatigue lasting several days to more than a week.

Although nausea, vomiting and diarrhea can sometimes accompany influenza infection, especially in children, gastrointestinal symptoms are rarely prominent. The illness that people often call "stomach flu" is not influenza.

Influenza is spread easily from person to person primarily when an infected person coughs or sneezes. After a person has been infected with the virus, symptoms usually appear within 2 to 4 days. The infection is considered often contagious for another 3 to 4 days after symptoms appear. (Because of this, people used to think the flu was caused by the "influence of the stars and planets." In the 1500s, the Italians called the disease "influenza," their word for influence.)

Each year, an estimated 10 to 20 percent of the population contracts influenza. In any year, influenza either produces an epidemic or a pandemic. In normal years influenza epidemics cause between three and five million cases of severe illness and up to 500,000 deaths, worldwide. A recent study by the Centers for Disease Control (CDC) estimated that an average of 36,000 deaths each year occur due to influenza-related complications in America. Every ten to twenty years a pandemic occurs, which infects a large proportion of the world's population, and can kill millions of people.

Good health habits can help prevent the flu, such as:

• Avoid close contact with people who are sick. When you are sick, keep your distance from others to protect them from getting sick too.
• Stay home when you are sick, if possible. You will help prevent others from catching your illness.
• Cover your mouth and nose with a tissue when coughing or sneezing. It may prevent those around you from getting sick.
• Wash your hands often to help protect yourself from germs.
• Avoid touching your eyes, nose or mouth. Germs are often spread when a person touches something that is contaminated with germs and then touches his or her eyes, nose, or mouth.

Another way to help prevent the flu is to get a flu shot before or during flu season (see below).

If you get the flu, you will need to do the following:

• Rest.
• Drink plenty of liquids.
• Avoid using alcohol and tobacco.
• Take medication to relieve the symptoms of flu (but never give aspirin to children or teenagers who have flu-like symptoms - and particularly fever - without first speaking to your doctor).

Sometimes, your doctor may prescribe an antiviral drug to help shorten the time you have the flu. A virus causes the flu, so antibiotics (like penicillin) don't work to cure it. If you do get the flu, it is important that you limit your contact with others, so that they don't catch the flu from you. Remember to wash your hands frequently with warm soapy water.

Vaccination against influenza with a flu vaccine is possible and in many cases recommended. The effectiveness of flu vaccines is highly variable. Due to the high mutability of the virus, a particular flu vaccine formulation usually confers protection for no more than a few years. The World Health Organization predicts each year which strains of the virus are most likely to be circulating in the next year, allowing pharmaceutical companies to develop vaccines that will provide immunity against these strains.

It is possible to get vaccinated and still get influenza. The vaccine is reformulated each season for a few specific flu strains, but cannot possibly include all the different strains actively infecting people in the world for that season. It takes about six months for the manufacturers to formulate and produce the millions of doses required to deal with the seasonal epidemics; occasionally a new or overlooked strain becomes prominent during that six month period and infects people even though they have been vaccinated (as in the 2003-2004 season). It is possible to get infected just before vaccination and still get sick with the very strain that the vaccine is supposed to prevent, as the vaccine will take a few days to become effective. The CDC says: “About 2 weeks after vaccination, antibodies that provide protection against influenza virus infection develop in the body."

Vaccination is most important in vulnerable populations, such as children or the elderly. The 2006-2007 season is the first in which the U.S. CDC has recommended that children (under 59 months) receive the annual flu vaccine. Vaccines can cause the immune system to react as if the body was actually being infected, and general infection symptoms (many cold and flu symptoms are just general infection symptoms) can appear, though these symptoms are usually not as severe or as long-lasting as influenza.

The CDC says: "The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. The risk of a flu shot causing serious harm, or death, is extremely small. However, a vaccine, like any medicine, may rarely cause serious problems, such as severe allergic reactions. Almost all people who get influenza vaccine have no serious problems from it."

The flu vaccine remains the best protection for Medicare beneficiaries. Adults who are age 65 and older, and other Americans with chronic illnesses, are in the high priority group to obtain flu vaccines. Of the 36,000 deaths attributed to flu and pneumonia in the United States each year, more than 90 percent of these deaths occur in people age 65 and older. Many of the deaths occur in patients who experience complications after the flu, such as pneumonia. These complications can be alleviated with flu medicines taken early in the course of disease.

Medicare will pay for the flu shot once every flu season. In some cases this may mean twice in one year. For example, if you received a shot in January 2006 for one flu season, you could be inoculated again in October 2006 for another flu season.

Senior citizens on Medicare.

Many companies, including Life Alert, provide their employees with free flu shots. Other businesses may provide them at low or reduced cost. We encourage our readers to check with the firms they work for, or their local medical facilities, to see if there is a flu shot program available in their area. Especially for older members of society, it can be a lifesaver.

Frequently Asked Questions about the Flu and Flu Vaccine.

http://en.wikipedia.org/wiki/Influenza - “Influenza” entry in Wikipedia.

http://en.wikipedia.org/wiki/Flu_vaccine - “Flu vaccine” entry in Wikipedia.

www.medicare.gov - official U.S. Government site for people with Medicare.

www.cms.hhs.gov – Centers for Medicare & Medicaid Services, a U.S. Department of Health & Human Services subsite.

For additional information about the flu to protect yourself and your loved ones, please visit the CDC website.