"We went to the hospital and they told us it was dehydration, but I knew there was something deeply wrong," Kerry's sister Katherine Stoutenburgh, 22, tells PEOPLE

New York Teen Dies from Brain-Eating Amoeba After Contracting Infection on Vacation: 'She Was a Shining Light,' Says Mom

Vibrant and vivacious Kerry Stoutenburgh, a 19-year-old from Kingston, New York, has

died after contracting a brain-eating amoeba called Naegleria Fowleri while on vacation in Maryland.

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Kerry, a junior studying cinematography at Brooklyn College, began complaining of a headache and sensitivity to light days after returning from time spent with her boyfriend and family swimming in Conowingo creek in August.

“We went to the hospital and they told us it was dehydration, but I knew there was something deeply wrong,” Kerry’s sister, Katherine Stoutenburgh, 22, tells PEOPLE. “She was discharged from the hospital and she came home to take a nap. When she woke up she was running around and yelling gibberish.”

“It was terrifying.”

Kerry’s loved ones, who rushed her back to the emergency room when she became combative and incoherent, remember her as “a brave, beautiful and brilliant human being – until the very end.”

“She was never scared of anything and lived every day to the fullest and that never stopped,” Kerry’s mother, Wendy Stoutenburgh, 48, tells PEOPLE.

The deadly amoeba, found predominantly in warm freshwater rivers or in soil, enters the body through the nose and makes it way to the brain where it destroys tissue. The resulting infection generally causes seizures, hallucinations and eventually death – within five days. It has a fatality rate of over 97 percent, according to the CDC.

“It got to the point where I looked at my husband and said, ‘This is not my daughter,’ “says Wendy of Kerry before her death on Aug. 31.

Kerry’s boyfriend, Luke Carquillat, says he is working on finishing a movie project Kerry started this summer.

“Cinematography was her passion and this summer we went to Brighton Beach almost every day where she filmed the landscape and people,” Carquillat, 20, tells PEOPLE. “She captured things that other people didn’t. She saw the world differently.”

What You Need To Know About Naegleria Fowleri, The Brain-Eating Amoeba

Carquillat, who was with Kerry and her family in Maryland when she contracted the deadly amoeba, calls the incident a “freak accident.”

“There must have been 10 of us total, we were with Kerry’s cousins and she jumped from a bridge into the water like eight times and she’s usually good at keeping her nose closed and blowing out,” he says. “But one time she complained the water got up her nose. The doctor later said in that moment her fate was sealed.”

Carquillat refused to leave Kerry’s side in the days her condition worsened – first when she began vomiting and complaining of migraines and later on when she was rushed to the emergency room, “slowly losing her mind.”

“Two days before she died, when she started screaming and crawling on the floor, I had a feeling that I’d never get to talk to her again,” recalls Carquillat. “I yelled at her, ‘Lovey, wake up! Wake up! Wake up!’ ”

“But I knew she was gone.”

Kerry was declared brain dead on Aug. 30 and the next day, after a culture came back confirming the Naegleria Fowleri diagnosis, doctors took her off of life support.

“They had done a spinal tap and originally thought it was meningitis,” says Carquillat. “But it turned out to be something so rare, so unfair. It just doesn’t make sense.”

Wendy, who says “not a minute goes by” that she doesn’t think about her daughter, is left with one big lingering question: Why?

“Why? Why is this happening? Why her? Why now? Why so young?” she says. “She’s mad up in heaven, I think, wondering why.”

“We feel guilty, but it’s not our fault because there was nothing we could do to stop this amoeba – it’s so rare and so unexpected.”

Instead of thinking about Kerry’s state during her last days, the Stoutenburghs prefer to remember the young woman she was prior to her infection.

“She was so much more than just the way she passed,” says Katie of her sister. “She was going on to do big things in the film industry and she had such a bright, bright future ahead of her.”

“She was a member of the high school marching band and the varsity swim team and in Girl Scouts in high school,” says Wendy, who led Kerry’s troop. “She was always on to bigger and better things and we expected her to persevere and do good in the world.”

“She was a shining light.”

Other parents who have lost children to Naegleria Fowleri reached out to Wendy and her husband Donald Stoutenburgh after Kerry’s passing.

“It’s unexplainable,” says Wendy of the amoeba that has infected 37 people in the last 10 years in the U.S. “We are trying to come together to get something in place so that when kids come to the emergency room there’s a system to detect it.”