Fourteen-year-old Hunter Boutain died Thursday at a hospital in Minneapolis, just days after being exposed to a deadly amoeba while swimming in a central Minnesota lake.

"Hunter's condition deteriorated throughout the night and he was declared brain dead this morning," said his uncle, Bryan, in a statement provided by the University of Minnesota Masonic Children's Hospital, where the teen had been treated. "Hunter died surrounded by his family."

It was the third confirmed Minnesota death since 2010 from a brain infection caused by exposure while swimming to Naegleria fowleri. All the victims were children.

The infection is considered extremely rare — fewer than 130 deaths have been confirmed nationally since 1962. But state health officials nonetheless encouraged people to take precautions such as keeping their heads above water when swimming or plugging their noses or using nose clips.

Boutain had been swimming earlier in the week at Lake Minnewaska, a popular recreation lake near Glenwood and Alexandria.

Mourners offered prayers and condolences on the family's CaringBridge website, while Boutain's brother, Lee, tried to articulate his pain on his Facebook page. "The Lord didn't want him to stay on earth," he wrote.

Boutain had completed eighth grade at Discovery Middle School in Alexandria, where he played in the orchestra and jazz band and helped produce an in-school TV news show. The school district called his death "heartbreaking" in a statement and said it is assembling a crisis response plan to "support the emotional needs of the family, and our students and staff as they come to terms with this tragedy."

Ten lakes tested

The rapid deterioration of a loved one infected with Naegleria fowleri — healthy and swimming only days earlier — is shocking to families, said Chad LaMeyer, creator of the Swim Above Water advocacy organization. LaMeyer's 11-year-old daughter, Hailee, died of a brain infection that appears to have been an unconfirmed case of Naegleria fowleri exposure in a lake in Stacy, Minn.

Her death resembled the deaths of two children in 2010 and 2012 from exposure to the parasitic infection in Lily Lake in Stillwater. Almost all U.S. cases have been fatal.

After the first case, the U.S. Centers for Disease Control and Prevention tested Lily Lake and nine others in Washington County between 2010 and 2014. Six tested positive for the amoeba in 2010, but no trace was found in any of the water samples in 2013 or 2014.

Infections are rare, even when Naegleria fowleri is in a body of water, and occur only when the parasite enters through the nose, said Trisha Robinson, supervisor of the waterborne diseases unit for the Minnesota Department of Health.

The presence of three confirmed cases in Minnesota — given that most cases have occurred in warmer lakes in southern states — means that swimmers here should take precautions, she said. One is that swimmers shouldn't kick up sediment from the lake bottom, because that can circulate the amoeba in the water.

Reactions to Boutain's death came swiftly on the Facebook page of the Swim Above Water organization.

"Prayers to the family," wrote Bridget Johnson. "I have been following Swim Above Water for a long time now and it scares the hell out of me. My family has a cabin up around Lake Mille Lacs and I just am terrified. My heart breaks for all of you that lost a child to this. I can't even begin to put it into words."