Aug. 15, 2011 -- A deadly brain parasite contracted during a swim in a local river is thought to be the culprit behind the sudden and tragic death of 16-year-old Florida teen, Courtney Nash.

Nash had gone for a swim Aug. 3 with her cousins in St. John's river and within a week began suffering from headache, stiffness, fever, and nausea -- all telltale signs of amoebic meningoencephalitis, a parasitic infection that attacks the brain and spine, Barry Inman, an epidemiologist with the Brevard County Health Department told ABCnews.com. The parasite enters through the nose and then travels through the sinuses and infects the brain and cerebrospinal fluid. Though this parasite is very rare, it tends to grow more in stagnant, fresh water during high summer temperatures, Inman said.

Nash was taken initially to a local hospital and then to Arnold Palmer Hospital for Children in Orlando, but despite every attempt at treatment, she died Saturday afternoon.

Doctors at Arnold Palmer identified the amoeba Naegleria fowleri in her system before her death and the Centers for Disease Control and Prevention have confirmed that this was in fact the infection that killed her.

Nash's is only the third case of amoebic meningoencephalitis in Brevard County since 1985, Inman said. Nationwide, there are usually one to three cases each year of this rare and dangerous parasitic infection. Only one person has survived the infection since the 1970s, he added.

"She was out swimming...in the St. John's River, having fun like any other kids would in the water," Nash's uncle Tom Uzel said at a press conference Monday morning. Nash and her siblings and cousins had swum in that river all their lives.

Courtney Nash Was an Organ Donor

Though chances of contracting this parasite are about one in 10 million, said Inman, people in the area are aware that there is some risk in swimming in certain fresh water ponds, lakes, and rivers.

"We have signs up in public fresh waters. All we can do is inform people that the organism is there. It's going to proliferate and grow, especially in the hot months. There are nose clips people can wear to reduce risk, but someone who doesn't want any risk needs to stay out of fresh water ponds and streams, especially those that are stagnant," Inman said.

Nash's family is taking solace in the fact that the teen had registered to be an organ donor just a week before her fatal swim. After Nash was declared to have no brain function on Saturday, doctors quickly went to work donating her organs.

"What's helping me through this is knowing my daughter was an organ donor. They took her into surgery at 4 o'clock, by 8:30 both lungs were already transplanted, the liver, pancreas. This morning they're putting kidneys in. They're doing several more later today," Nash's mother P.J. Nash said at the press conference. She called the donations a "miracle."

The teen's mother also requested that public health officials offer a blurb during the summertime to alert the public to the dangers of "hot waters" and parasites. "If we could save other peoples' lives and they wouldn't have to go through what I went through, I think this would just be a blessing in disguise," she said.

Inman said that anyone suffering from the symptoms of this parasitic infection -- fever, nausea, stiff neck, and a frontal headache -- should seek medical attention.