According to a post on his CaringBridge page, former St. Louis Park baseball star Derrick Keller has cytomegalovirus, or CMV.

The virus is in the same family as mononucleosis, and can cause fever, swollen glands and a tired feeling. People with a compromised immune system—like Keller, who underwent chemotherapy to ward off leukemia—may experience more serious illness involving fever, pneumonia and other symptoms.

Here is more from Keller's family via CaringBridge:

Derrick needs some prayers and positive thoughts tonight. He does have the cmv virus in his lungs. He is hooked up to a bipap machine to help him with his breathing. It shoots oxygen up his nose, to his lungs. His lungs need to expand, and this machine is helping. He was having trouble breathing deep this morning.

He just needs to catch a damn break. This is so frustrating I don't know what to do. Linda and I are just going through the motions of life right now. To see DK in that hospital bed in pain, and having to wear that breathing mask, is making us crazy. This will get better, but we pray it will be sooner than later.