Influenza

Influenza, commonly known as the flu, is a respiratory infection caused by an influenza virus. The flu virus enters your body when you breathe in air containing infected droplets, usually generated by someone else's coughing or sneezing. Outbreaks occur nearly every winter, and vary in severity depending on that year's strain of the influenza virus.

If you are like most people, you have had the flu at some point in your life. You may have felt awful for a week or so, but you got over it. Some people, though, develop serious complications such as pneumonia. Some even die from the flu. Those most at risk for complications include infants, people over age 60, and those with heart disease, lung disease, or chronic diseases that weaken the immune system, such as diabetes.

The influenza virus can cause severe pneumonia. It can also weaken the lungs, allowing harmful bacteria to take over and cause bacterial pneumonia. This can happen even to healthy young adults.

Once exposed to a particular strain of flu, you are immune to that strain for life. But each year, there are new strains to which you have no immunity.

Prevention

There are many things you can do to avoid getting the flu:

Wash your hands. Washing your hands for at least 15 seconds with ordinary soap and water can help keep you flu-free. It's not necessary to use very hot water or "antibacterial" soaps. Alcohol-based hand rubs and gels also work.

Keep your distance. The flu is most contagious within three feet of someone who has it.

Wear a mask. If you are in a high-risk group and can't avoid getting up-close and personal with possible flu victims, wear a simple face mask. These are available in most pharmacies.

Protect others. Don't go to work or school if you have the flu.

Get vaccinated. Each year, a vaccine is made to fight the strains of influenza virus that are most likely heading our way in the fall. The Centers for Disease Control and Prevention recommend that everyone 6 months and older get a flu shot each year. Two types of flu vaccine are available:

• The injectable vaccine can be given to nearly everyone, except people who are allergic to eggs or to the vaccine itself.
• The nasal spray can be used only by healthy, non-pregnant individuals ages 2 to 49.

Side effects are mild and uncommon, amounting to a slightly sore arm or a slight fever.

Symptoms

Symptoms generally occur from 1 to 4 days after being exposed to the virus. This is called the incubation period. Flu symptoms generally include:

• a fever
• chills
• headache
• aching muscles
• fatigue
• sore throat
• cough

But keep in mind that symptoms vary widely from strain to strain and from person to person.

The fever usually rises gradually over the first day of illness and then declines. The flu usually runs its course in 5 to 7 days, but you may feel tired for several weeks.

Diagnosis

The flu is usually diagnosed based on your symptoms. Tests are rarely necessary.

Treatment options

The best treatments for the flu include

• rest
• drinking plenty of fluids
• taking nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen to relieve pain and fever. CAUTION: Infants and children under 21 years old should not take aspirin to lower a fever or ease pain because of the risk of Reye syndrome.
• warm fluids, to help soothe a sore throat
• humidified air, which can ease breathing difficulties. Call your doctor if you have trouble breathing or if your fever does not subside after 4 days.

If you are at high risk of complications from the flu, your doctor may recommend that you take an antiviral drug such as amantadine (Symmetrel), oseltamivir (Tamiflu), rimantadine (Flumadine), or zanamivir (Relenza) within 24 hours of the start of your symptoms to lessen the severity of the illness.

Antibiotics don't work against the flu because it is caused by a virus. Antibiotics only fight bacterial infections. If the flu has led to a bacterial infection of your sinuses or lungs, then your doctor might prescribe an antibiotic.