OKLAHOMA CITY - The number of people dead of flu-related causes has now risen to 11. The state health department confirms one new flu-related death within the last week.

Since September, nearly 250 people have gotten so sick they had to go to the hospital. Tulsa has had more of those cases than any other county in the state with 63.

Influenza is a highly contagious respiratory illness caused by a virus which is spread by infected people coughing, sneezing or touching a surface handled by others. Its impact can be severe in some cases, especially among seniors, young children, pregnant women and people with underlying medical conditions, according to the CDC.