A Florida teen recently died of the “kissing disease," or mononucleosis, her father said.

Ariana Rae Delfs, 17, of Fernandina Beach, died after falling ill about three weeks ago, according to local news station WJAX-TV. The teen’s father, Mark Delfs, said Ariana had coldlike symptoms and “seemed to always have a headache" in the weeks before her death.

“The persistent thing all the way through was the headache,” he said.

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When Ariana failed to improve, her parents took her to a doctor who ran various tests, including one for mono, as per the news station. But a formal diagnosis was not made.

The teen’s symptoms continued to worsen. She was rushed to the hospital the morning after she spent one night “throwing up just constantly,” said Delfs. “We got very nervous.”

At the hospital, Ariana stood up at one point to use the restroom but told her parents she could not feel her legs.

“She felt like her legs were just giving out,” her father said.

Doctors suspected the 17-year-old was suffering a stroke and she was subsequently airlifted to a hospital in Jacksonville.

“Her words were very slurred at times. She was just talking gibberish, and the damage was already beginning at that point, which we just didn’t know,” said Delfs.

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Sadly, Ariana received a formal diagnosis in the final days of her life: Epstein-Barr virus (EBV), which causes mononucleosis. The Mayo Clinic says the virus is the most common cause of mononucleosis.

The teen’s brain swelled to the point where it was not able to properly function, meaning Ariana suffered irreversible brain damage. At that point, “we just made the decision that it was time to let her go,” her father told the news station.

Following his daughter’s death, Delfs is urging other parents to take their children’s symptoms seriously and “be on top of it.”

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“In our case, it wasn’t enough, but in somebody else’s case it may save their life,” he said.

Ariana, a scholar-athlete at Fernandina Beach High School, an artist, and self-taught musician, was “a very giving soul,” Delfs added. “She would give anybody anything.”

The teen’s funeral was on Wednesday. Her family has also set up a GoFundMe to raise money for “some of her passions, including music and arts programs for children, helping animals and making the world a better place," the fundraiser reads.