(CNN) -- The University of West Georgia graduate student infected with rare "flesh-eating" bacteria has proven to be "amazingly resilient," her father said Wednesday, and a second apparent case has been reported.
"It's phenomenal the change we've seen in the past week," said Andy Copeland, whose 24-year-old daughter Aimee was on a ventilator in intensive care at Doctors Hospital in Augusta, Georgia.
"Today, she's actually doing very well," he told Jane Velez-Mitchell of CNN's sister station HLN. "She was in high spirits."
The master's student in psychology at the Carrollton school was with friends on May 1 near the Little Tallapoosa River, about 50 miles west of Atlanta, when she grabbed onto a zip line. It snapped and she fell.
The accident left a gash in her left calf that took 22 staples to close.
Three days later, still in pain, she went to an emergency room, where doctors determined she had necrotizing fasciitis caused by the flesh-devouring bacteria Aeromonas hydrophila. She was flown to Augusta for surgery.
Since then, doctors have removed part of Copeland's abdomen, amputated a leg and expect to remove her fingers, her father said.
"We're unclear if she actually knows about the leg," he said. "Right now, she does know about the condition of her hands, though. She knows there has been some atrophy -- or basically a loss of blood flow in that area."
The father said there was no immediate need for surgeons to remove her fingers, which he described as being in a state of "dry gangrene ... her fingers basically, at this point, are necrotized. It's dead flesh; they will ultimately have to be removed."
Copeland, who has been on life support since May 4, regained consciousness a week later, the school's website said.
She has since undergone a tracheotomy. "I hope it will be easier to understand her," said Aimee Copeland's sister Paige. Until now, the family has been playing a form of charades in an attempt to decipher her words, which the ventilator's presence has been made difficult to understand, she said.
Copeland has been infused with 177 units of blood since she contracted the infection. That's more than 168 pints; the average human body contains about 10 pints of blood, according to America's Blood Centers.
The bacteria are "remarkably common in the water and in the environment," according to Dr. Buddy Creech, an assistant professor of pediatric infectious diseases at Vanderbilt University.
He said it was not clear how many cases occur in the United States in any given year. "For pediatrics, we only see two or three a year," he said, referring to Vanderbilt.
"When it gets into those deeper tissues, it has a remarkable ability to destroy the tissues that surround it in sort of this hunt for nutrition," he said. "When it does that, those tissues die, and you see the inflammation and the swelling and the destruction that can be very difficult to control."
The infection is fatal in about one in four cases, the Centers for Disease Control and Prevention says on its website.
A similar if apparently less severe case was reported by the husband of a 36-year-old paramedic and nurse from Greenville, South Carolina, who gave birth to twins on May 7 at a hospital in Georgia.
The couple had traveled to Atlanta because they had found there a doctor who was willing to perform a vaginal delivery even if the babies were in the breach position. Some doctors prefer to perform cesarean sections in such cases.
Other than a minor tear that was sewn up and the loss of "a lot of blood" that required a transfusion, Lana Kuykendall's vaginal deliveries of twins Abigail and Ian were uneventful, said her husband, Darren Kuykendall, a 42-year-old firefighter.
But when Lana Kuykendall failed to feel better by Thursday, she checked out of the Atlanta hospital and traveled back to Greenville.
"We discharged because we wanted to come home and see if we could get her better, because they couldn't figure out what was wrong with her," het said.
But once she was home with her babies, Lana Kuykendall's condition worsened.
On Friday morning, "she woke up and she had a big bruise on the back of her leg and it looked like a blood clot," Darren Kuykendall said. "That spot just got bigger and bigger as she laid there. Literally, you could almost watch it grow as you're standing there."
He then took his wife to Greenville Memorial Hospital.
"One of the OB doctors realized what it kind of looked like, and she went and got the surgeon, and they all made the decision that it was definitely necrotizing fasciitis, so they took her immediately to surgery," he said.
By then, the affected tissue "had almost encircled her leg."
In separate procedures on Friday, Saturday and Sunday, surgeons cut out dead skin and tissue from both legs to keep the infection from spreading and put her on antibiotics, said Kuykendall. "It's hopefully on its way to healing," he said. "She's sedated and on a ventilator."
Though Lana Kuykendall's organs remain in good shape, "they told me it could still go either way," her husband said. Still, he added, "she's critical, but likely she's going to be OK."
Sandy Dees, the hospital's public relations officer, could only confirm Wednesday night that her condition was critical but stable. The two doctors whom Darren Kuykendall identified as having treated his wife have not responded to requests for comment.
Meanwhile, infants Abigail and Ian are in the care of family and friends, Kuykendall said.