MINNEAPOLIS (WCCO) – The Health Department is investigating after a suspected amebic infection killed a 9-year-old boy who had gone swimming in warm Washington County lakes.

Authorities said Tuesday that the suspected amoeba is Naegleria fowleri, which is commonly found in warm freshwater. The amoeba can cause a “severe brain infection and is nearly always fatal,” the department said.

Health officials said the boy went swimming at multiple locations in Washington County two weeks before the onset of illness. One of the lakes was Lily Lake in Stillwater – the suspected source of a previous infection that killed a 7-year-old girl in August of 2010.

Lily Lake is now closed for swimming, the department said.

Naegleria fowleri enters the body through the nose. This happens, usually, when people are swimming in warm freshwater, the department said.

Infections are rare, despite the fact the amoeba is commonly found in freshwater worldwide. Only 40 cases were reported in the U.S. from 2001 to 2011. Generally, infections occur in the south.

The 2010 case mentioned above is the only previously confirmed case of the infection in Minnesota, the department said.

“The risk of infection from Naegleria in Minnesota is very low,” said Richard Danila, an assistant state epidemiologist. “Swimming is a very healthy summertime activity and we do not want to discourage people from swimming. Rather, simply avoid swimming, diving or other activities in obviously stagnant water when temperatures are high and water levels are low.”

Danila said there’s been only 125 cases of the infection in the last 85 years.

“With hundreds of thousands of bodies of water and millions of people swimming in them every day, it’s extremely rare,” he said.

The infection Naegleria causes is a form of meningitis called primary amebic meningoencephalitis (PAM), the department said.

Health officials will confirm the boy’s cause of death with the assistance of the Centers for Disease Control and Prevention.

A memorial fund has been set up for the child at the Unity Bank of Rush City, 1180 W. 4th St., Rush City, MN 55069. Memorial donations can be sent in the name of the Jack Erenberg Memorial Fund.

Symptoms To Watch For:

Call a doctor immediately if your child has headaches, a stiff neck and starts vomiting after being in a warm lake.

Also, while swimming, consider using nose plugs and avoiding shallow, warm lakes where the amoeba is more likely to grow.