Influenza (Flu)

Alternative Names

Influenza A; Influenza B

What is Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. It affects all age groups, though kids tend to get it more often than adults.

Flu season runs from November to April, with most cases occurring between late December and early March.

Signs and symptoms

Symptoms, which usually begin about 2 days after exposure to the virus, can include:

• fever (usually high)
• headache
• extreme tiredness
• dry cough
• sore throat
• runny or stuffy nose
• muscle aches
• stomach symptoms, such as nausea, vomiting, and diarrhea, may occur in children but are rare in adults

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Possible complications

Complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

What causes

Influenza is caused by a virus in the body; the family of RNA viruses that cause influenza in humans is Orthomyxoviridae. Flu spreads when infected persons cough, sneeze, or even talk around others. People with flu are contagious a day before symptoms appear and three to seven days after. Children can be contagious for more than a week. You can get the flu simply by touching a surface like a telephone, keyboard or doorknob that has been contaminated and then from your hand to your nose or mouth. Breathing the air within a six foot diameter of a person sneezing or coughing may also transmit the virus to you in respiratory droplets.

Prevention

• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Wash your hands often with soap and water, especially after you cough or sneeze. You can also use an alcohol-based hand cleaner.
• Avoid touching your eyes, nose or mouth. Germs spread this way.
• Try to avoid close contact with sick people.
• While sick, limit contact with others as much as possible to keep from infecting them.

Treatment

General Treatment

• Give ONLY non-aspirin medicines such as acetaminophen (Tylenol) to children for fever, muscle aches and headaches.
• Ibuprofen-containing pain relievers (e.g., Advil or Motrin) can be used for fever and pain in older adolescents and adults.
• Drink plenty of fluids to prevent secretions from getting thick and increasing breathing problems.
• Rest to help your body fight the infection.
• Antiviral medicines can be used.
• Antibiotics are of absolutely no use for influenza and are used only for bacterial complications after the acute phase is over.

The New Flu Drugs

• An exciting new class of drugs is just now becoming available for the treatment of influenza. These drugs, called neuraminidase inhibitors, help stop influenza virus replication and are active against influenza types A and B.
• Zanamivir for inhalation (Relenza®, a trademark of GlaxoWellcome) is the first of these new drugs to be approved by the FDA.
• Relenza has been shown to shorten the duration of flu symptoms if given within 48 hours of symptom onset. Thus it is important to see your doctor at the first sign of flu symptoms to receive effective treatment.
• Relenza, which is administered with the help of a special inhaler, is approved for use in those 12 years of age and older. The normal dosage is two inhalations for 5 days.
• Another new drug in this class is oseltamivir (Tamiflu®, a trademark of Roche). Like Relenza.