After the death of a 9-year-old boy Tuesday, officials moved quickly to close Stillwater's Lily Lake, with signs warning visitors to "Stay Out of the Water" and yellow "Danger" tape.
Jack Ariola Erenberg is the second child since 2010 to die of a rare brain infection believed to have come from an amoeba in the 36-acre lake.
"This is an incredible, tragic event," said Michael Beach, an author and a leading researcher on the amoeba for the Centers for Disease Control and Prevention (CDC) in Atlanta.
Still, Beach said, he and other national authorities wouldn't urge that all swimming stop in natural bodies of water, given the benefits and the extremely low risk. Officials do not want to minimize the deaths, Beach said, but they also are not willing to tell hundreds of millions of people to stop visiting lakes, streams and rivers.
Beach and others are trying to develop a practical, fast way to check water for the organism, known as Naegleria fowleri. It's the second time that a Minnesotan has died of meningitis caused by the microscopic amoeba. Though such infections are rare worldwide, 7-year-old Annie Elizabeth Bahneman of Stillwater also died after swimming in the same lake in 2010.
Officials at the Minnesota Department of Health are awaiting confirmation from the CDC but are 99 percent certain that the boy's death was caused by the amoeba, said Richard Danila, assistant state epidemiologist.
Jack's father, Jim Ariola of Wyoming, Minn., said he wouldn't have let his son swim there if he had known another child died. He feels that warning signs should have been posted at the lake.
"You can't keep your kids out of lakes, you know," Ariola said. "Who all has a pool? When I was little, I swam in that lake because I had hockey camp right there at Lily Lake. If they open the beach, I'm sure kids would be there today."