Gov. Phil Bredesen remained in a hospital Wednesday for further observation after suffering flu-like symptoms that doctors believe may have been caused by a tick bite, his spokeswoman said.

Bredesen, 62, fell ill with a severe headache and high fever and was admitted to Centennial Medical Center in Nashville on Monday night.

"Governor Phil Bredesen today remains at Centennial Medical Center in Nashville undergoing additional medical tests and observation for flu-like symptoms," spokeswoman Lydia Lenker said Wednesday. "Medical staff concur the likely cause of the symptoms is a tick bite."

Lenker said the governor is being kept over because doctors want to be certain he is healthy before releasing him.

Ticks in Tennessee are commonly associated with transmitting Lyme disease, which can cause symptoms similar to those suffered by the governor. Lenker said she did not know if doctors believed Bredesen had been exposed to Lyme disease.

Dr. Lyric Bartholomay, assistant professor of medical entomology at Iowa State University, said there are tick-borne agents that can cause flu-like symptons. However, she said the amount of time a tick spends on a person is important.

"If he had a tick and removed it quickly, it's not likely" to have caused the symptoms, Bartholomay said. "Usually it takes several days for a tick to transport a disease. It's all a timing issue."

She said once a tick is spotted, it should be removed right away, using tweezers if possible.

"Take really fine tweezers, push down to the skin, and pull the tick straight out," Bartholomay said. "You don't want to do anything that will make the tick regurgitate and infect you with any disease agent it might be carrying."

Lenker did not say when the governor may have encountered a tick, but she said he enjoys outdoor activities like fishing, and has had several outdoor events in recent weeks as he campaigns for re-election.

Despite being hospitalized, Lenker said "the governor is in good spirits and staying abreast of business at the Capitol."