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.
Although most people are ill for only a few days, some people have a much more serious illness, such as pneumonia, and may need to be hospitalized. Thousands of people die each year in the United States from the flu or related complications. Symptoms can occur within 1 to 3 days after exposure to an infected person . Usually, a doctor will diagnose a case of the flu based on typical symptoms of fever, chills, headaches, cough and body aches. There are a variety of tests that can be used to detect influenza.