Doctors now say an experimental drug could be the key to saving a 12 year old girl fighting for her life after coming into contact with a brain-eating amoeba during a trip to an Arkansas water park.

“When Kali Hardig arrived at Arkansas Children's Hospital, she was so exhausted she couldn't even answer the doctor's questions,” CNN Senior Medical Correspondent Elizabeth Cohen reports.

The doctor ran tests that showed Kali had a rare and almost always deadly infection. Swimming around in her spinal fluid were the brain-eating amoebas.

“Kali's parents were told she might have only days to live,” Cohen says.

“To preserve brain tissue, Kali's doctors induced a coma and cooled her body to 93 degrees. Doctors also turned to the Centers for Disease Control for an experimental anti-amoeba drug, unsure if it would work.”

But it’s given her a fighting chance. “Now there's now no trace of the amoebas in Kali's spinal fluid,” Cohen says.

Dr. Sanjiv Pasala says, “Day by day she's showing slow improvement and we're all very optimistic.”

Yet Kali still remains in intensive care in critical condition.

“Killing the amoebas is one thing, but managing brain swelling and the aftermath of the infection and the irritation to the brain is really the critical part in having a patient survive,” Dr. Pasala says.

“If Kali does pull through, she'll beat the odds: Only one person in the US has survived this disease in the past 50 years,” Cohen reports.

“Kali's parents are praying she'll be number two.”