The father of a boy who died after swimming in a Stillwater lake has filed a wrongful-death lawsuit alleging that the city, county and state failed to issue appropriate warnings to the public.

Jack Ariola Erenberg, 9, of Stillwater, died from a rare parasite in August after swimming in Lily Lake, which has a small beach. His death came two years after Annie Bahneman, 7, of Stillwater, also died from the Naegleria fowleri amoeba, which was traced to her swimming in the same lake. The parasite, commonly found in warm freshwater and soil, causes a rare but severe brain infection that is nearly always fatal.

The suit filed Friday by James Ariola in Dakota County District Court targets the city of Stillwater, the Stillwater Parks and Recreation Commission, Washington County and the Minnesota Department of Health.

"The failures by the defendants to issue the appropriate warnings caused or contributed to the death of Jack because his parents would not have brought him to Lily Lake for unprotected swimming otherwise," the suit said.

Attorneys representing the various defendants declined comment Friday.

However, a state health official said at a public meeting in Stillwater in late August that many Minnesota lakes could have the parasite -- particularly in prolonged stretches of summer heat -- and it can come and go unpredictably. "It's not something that's quickly detectable, and it's not something that's going to be consistent," Jim Koppel, deputy commissioner at the state health agency, said then.

Infections are caused when water enters the nose, enabling the one-celled organism to crawl into the brain. Most cases have occurred in Southern states, according to the Centers for Disease Control. Lily Lake's beach was closed after Jack's death. Health officials warned the parasite could be found in warm water anywhere and that swimmers should not assume that closing Lily Lake meant other lakes were safe.

Jack had fallen ill and become dizzy while camping with his mother and other family members in the Grand Marais area. At first, doctors thought it was flu, and Jack returned to camp. He became sicker, with a bad headache, and a medical helicopter flew the boy from Grand Marais to Duluth, where he died. Jack was to have begun fourth grade this year at Lily Lake Elementary in Stillwater.

Annie Bahneman died from primary amebic meningoencephalitis (PAM), a rare form of meningitis, state health officials said. She died at Children's Hospital in St. Paul four days after she fell sick with vomiting and a headache. Also cited in Ariola's suit was the 2008 death of 12-year-old Hailee LaMeyer of Stacy, Minn., after swimming in Fawn Lake near her home.

Before Jack's death, defendants should have known that the organism presented a general danger to anyone "who might go swimming in unchlorinated waters, especially young children and others with immature or compromised immune systems," the suit said.

It seeks damages exceeding $50,000, an injunction ordering the city to post conspicuous warnings at Lily Lake, an order that the city distribute information about the lake's risks, and possibly build a chlorinated pool. It also includes an order that defendants pay all legal costs for Ariola, of Wyoming, Minn.

His attorneys are Sharon K. Sill of Forest Lake and Robert Strassburg of Scottsdale, Ariz.

Kevin Giles • 651-925-5037 Twitter: @stribgiles