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What Is the Flu?

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Influenza (the flu) is a broad term for several types of contagious upper respiratory infections caused by different viruses.

Seasonal flu is usually the most common strain.

Visit any Marshfield Clinic primary care location during regular business hours for your flu shot.

Seasonal flu is an infection of the nose, throat and lungs. A virus that infects many people every winter causes it.

The flu usually spreads from person to person when an infected person coughs, sneezes or talks and expels the virus into the air. You can also contract the virus by handling an object touched by an infected person.

Someone with the flu is usually contagious from a day before feeling sick until the fever is gone.

The flu may cause symptoms ranging from mild to life threatening. Every year in the United States, on average 5 to 20 percent of the population gets the flu; more than 200,000 people are hospitalized from flu complications, and; about 24,000 people die from flu-related causes, according to the Centers for Disease Control and Prevention (CDC).

What are the symptoms of flu?

Symptoms of flu include:

  • Sudden chills and fever (102-103° F) 
  • Headache 
  • Muscle aches and pains 
  • Sore throat
  • Dry cough 
  • Runny nose
  • Nasal congestion 
  • Fatigue
  • Weakness
  • Loss of appetite

The seasonal flu virus usually changes, or mutates, every year. Because of this change, a new vaccine is required every year to prevent the disease. A flu shot is your best defense against the disease.​


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