The meningitis that killed a 7-year-old Stillwater girl on Saturday was caused by an amoeba associated with swimming in warm fresh water, the Minnesota Department of Health said Thursday.

Annie Elizabeth Bahneman died at Children's Hospital in St. Paul just four days after she fell sick with vomiting and a headache. Tissue and spinal fluid samples were sent to the national Centers for Disease Control and Prevention to help find the cause.

Health officials said Annie had gone swimming at several locations in the weeks preceding her infection.

Her death was caused by primary amebic meningoencephalitis (PAM), a rare form of meningitis, the health department said. The organism is known as Naegleria fowleri, an amoeba commonly found in warm fresh water and soil that causes a rare but severe brain infection and is nearly always fatal.

The organism enters the body through the nose, often during swimming or diving.

"Since this organism is known to be associated with warmer water, it is understandable that this infection occurred in a year that has been unseasonably warm for fresh water in the state," said Dr. Richard Danila, an epidemiologist with MDH.

Danila said Annie's death doesn't mean increased risk to the public from freshwater. The organism could occur anywhere but is more likely to be found in shallower, warmer, stagnant bodies of water, he said.

"Swimming is a very healthy, summertime activity and we do not want to discourage people from swimming," he said.

While it can occur anywhere, infection with Naegleria is more common in warm southern states. Thirty-three infections were reported nationwide in the 10 years ending in 2007, the MDH said. By comparison, 36,000 drownings occurred in a similar 10-year period, the MDH said.

Annie would have been a first-grader at St. Croix Preparatory Academy in Washington County.

Services are scheduled for 11 a.m. Friday at Church of St. Michael, 611 S. 3rd St., Stillwater. Visitation will begin an hour earlier.

Donations to the Annie Bahneman Memorial Fund can be made at any Wells Fargo bank.

Kevin Giles • 651-735-3342