An 8-year-old girl in Louisiana has died after being infected by an extremely rare brain-eating amoeba that is found in warm freshwater, her family says.

Lillian Smart died over the weekend after being diagnosed with an infection from Naegleria fowleri, according to a spokesperson for her family. Health authorities describe it as a “brain-eating amoeba” that thrives in freshwater bodies around the U.S. and can shoot up the nose and cause an infection that almost always proves fatal. On average there are fewer than 10 cases annually in the U.S.

The Louisiana Department of Health, in a separate release announcing the case, said Naegleria fowleri ‘grows best’ in extended periods of extreme heat and lower water levels — conditions that have persisted across the Gulf South this summer.

“Last night Lillian ran from our arms to the arms of Jesus,” her parents, Daniel and Rebecca Smart, wrote Sunday in a public post on Facebook. “The injuries to her brain were too severe for her little body to recover from. Everyone did everything they could to keep her here.”

The Louisiana Department of Health said last week that the state had experienced its first confirmed Naegleria fowleri infection since 2013. The department, which did not identify Smart, does not comment on individual cases or specific patients, according to spokesperson Stacey Grow.