The infection attacks and destroys healthy tissue and is fatal about 20% of the time, according to the Centers for Disease Control and Prevention.

Dr. William Schaffner, chairman of the Department of Preventive Medicine at the Vanderbilt University Medical Center, estimates that fewer than 250 such cases occur each year in the United States, though estimates are imprecise since doctors do not have to report the cases to health authorities.

Andy Copeland says his daughter is "knocking it out in rehab," committed to her exercise regime like an Olympic athlete.

"Her face was red and the vein in her neck was bulging as she pressed herself into her repetitions with serious determination," Copeland said of Aimee's Tuesday workout. "It's like she was training for the Olympics."

On Wednesday, she will be fitted with test sockets for her prosthetics, her dad said. If all goes well, in a few weeks, she will begin to be fitted with prosthetic limbs.

But her progress appears to come with a tinge of sadness.

"As I sit here and type I realize just how fortunate I am, we are, to have hands," Andy Copeland said. "Take a moment tonight, tomorrow, every doggone day, to thank God for what you have. Taking time to realize your blessings makes life all the more worth living."