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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.

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

Flu viruses can cause infection of the nose, throat and lungs. Each year, seasonal strains of virus cause outbreaks of the infection.

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

People can be contagious with the flu a day before symptoms show, which makes it

so easy to spread the illness from one person to another.

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; between 140,000 and 710,000 people are hospitalized from flu complications, and; between 12,000 and 56,000 deaths are reported from flu-related causes, according to the Centers for Disease Control and Prevention (CDC).

What are the symptoms of flu?

Symptoms of flu include:

  • Fever* (102-103° F).
  • Cough.
  • Sore throat.
  • Runny or stuffy nose.
  • Body aches.
  • Headache.
  • Chills.
  • Fatigue.
  • Sometimes diarrhea and vomiting.

*It's important to note that not everyone with flu will have a fever.

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