Influenza, or flu, is a viral infection of the nose, throat, bronchial tubes and lungs.
Influenza occurs most often in the winter months.
Illnesses resembling influenza may occur in the summer months, but they are usually due to other viruses. Influenza surveillance is conducted by the South Dakota Department of Health and the Centers for Disease Control and Prevention each year from October through mid-May. Influenza is highly contagious and is easily transmitted through contact with droplets from the nose and throat of an infected person who is coughin g and sneezing. Typical flu symptoms include headache, fever, chills, cough and body aches. Intestinal symptoms are uncommon.