By Elizabeth Cohen, CNN

A 12-year-old girl in Arkansas is in critical condition, battling a rare but deadly brain-eating parasite.

What's more alarming is how doctors believe she got the infection; after going swimming at a water park.

Kali Hardig went for a swim in a lake at a water park in Little Rock, Ark., and is now fighting for her life. She contracted parasitic meningitis, a rare infection caused by a brain-eating amoeba. The infection has struck only 31 other people in the past 10 years, and the centers for disease control says all were fatal.

"The child has a grave prognosis, I'm afraid," said Dr. William Schaffner with the Vanderbilt University School of Medicine.

The amoeba, a parasite called naegleria, loves warm water, like lakes, rivers, and hot springs.

"The amoeba then finds itself way back in our noses and then can work its way into our central nervous system, around our brains, and once it's there it just causes destruction," said Dr. Schaffner.

Kali's mother took her daughter to the hospital when she noticed alarming symptoms, including exhaustion and high fever.

Doctors at Arkansas Children's Hospital have put kali in a coma to stabilize her, and the Willow Springs Water Park has closed down.

"It's hard for us to even think about the possibility of a child getting sick out here," said David Ratliff, owner of Willow Springs Water Park.

Kali's family is asking for prayers. On theirFacebook page they write, "she still has a long fight ahead."

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