Minnesota health officials are warning health care facilities after a Twin Cities child with the flu developed a case of rare brain inflammation.

The Minnesota Department of Health said the child, who is under 2, was diagnosed with influenza-associated acute necrotizing encephalitis. Also known as ANE, the condition causes rapid deterioration of the brain tissue. The department said ANE is "rare, however, the morbidity and mortality are high."

In addition to the local case, health officials said pediatricians across the country have noted an uptick of ANE cases this flu season. 

"Cases have typically been previously healthy young children, and many were unimmunized for influenza," the department said. "Clinical presentations have included high fever, obtundation, and most cases had seizures."

An optimal treatment for the condition is not known.

Officials are urging hospitals and other care clinics to watch for symptoms of ANE and encourage patients to get their flu shots — only 33.3% of Minnesotans are current on their flu vaccine, according to officials, and only 30.2% of children 9 and younger.

"Influenza vaccine helps reduce severe illness and remains one of the best ways to protect our most vulnerable populations," the department said.

According to the health department, there have been 6,124 influenza-related hospitalizations in Minnesota this season. That's 1,749 more than the year before and the highest mark in at least six years. There has been one pediatric flu death this season, the department said.

Flu rates across the country are high this season, according to the Centers for Disease Control and Prevention.