Wisconsin is one of 23 states reporting widespread influenza activity, along with nearby Illinois and Indiana, according to new findings from the Centers for Disease Control.

The state Department of Health defines influenza as a contagious disease caused by viruses that infect the respiratory tract. The viruses cause mild to severe illness, sometimes leading to death. Influenza symptoms often begin suddenly, with fever, headache, tiredness, dry cough, sore throat, nasal congestion and body aches, according to the CDC.

The government is urging people to get a flu shot and people experiencing flu-like symptoms may benefit from antiviral drugs. Such drugs “are an important second line of defense that can be used to treat flu illness” and should be taken as early as possible, according to the CDC.

“By protecting ourselves with a flu shot, we’re also helping to protect our family, friends, co-workers, and the rest of our community,” said state health officer Karen McKeown in a news release.

Those who are strongly encouraged to receive the flu shot include:

People 65 years old and older.