Otitis media, more commonly called an ear infection, is an inflammation of the middle ear, the space behind the eardrum. It can be caused by either a virus or bacteria and results in fluid build-up in the middle ear. Ear pain and fever are the most common symptoms. Ear drainage, or fluid that leaks from the ear, can also occur if the eardrum ruptures. Children are affected more frequently than adults, and about 5 of every 6 children will have experienced at least one infection by their first birthday.