kdshutterman/iStock(FORT WORTH, Texas) -- A 10-year-old girl is fighting for her life at a Texas hospital after contracting a rare brain-eating amoeba while swimming in a river.

Lily Mae Avant spent Labor Day weekend with her family swimming in the Brazos River, which winds through their backyard in Whitney, Texas, a small city near Waco. She came down with a headache and fever soon after, on Sept. 8. Over the following days, she began acting strangely, according to her family.

Lily, who had become incoherent and unresponsive, was flown to Cook Children's Medical Center in Fort Worth last Tuesday. Doctors say she contracted Naegleria fowleri, a rare but deadly amoeba that lives in warm freshwater such as lakes, rivers and hot springs. The single-celled organism typically infects swimmers by travelling through the nose and into the brain.

The fatality rate for Naegleria fowleri infections is over 97%. Only four out of 145 known-infected individuals in the United States have survived since the amoeba was first identified in the 1960s, according to the U.S. Centers for Disease Control and Prevention.

The Texas Department of State Health Services did not immediately respond to ABC News' request for comment Monday morning.

Lily was given an amoeba-fighting pill and was placed in a medically-induced coma in what has become the fight of her life.

"She's a fighter," Lily's stepfather, John Crawson, told Dallas ABC affiliate WFAA-TV in an interview Friday night. "And she's stronger than anyone I know."

Although the odds are stacked against her, Lily's family is holding out hope that she will be the fifth person to survive.

"She is still here with us," her aunt, Loni Yadon, told WFAA, "and we are still fighting."

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