Iowa beach shut down, woman infected with brain-eating amoeba

A freshwater beach in Southern Iowa was forced to close Friday after a woman who recently swam there became infected with Naegleria fowleri, a brain-eating amoeba, state health officials announced.

The swimmer, a woman from Missouri, was in the water at the Lake of Three Fires in Taylor County towards the end of last month. She was later confirmed to be infected with the single-celled, free-living amoeba that can cause a “life-threatening infection of the brain,” the Iowa Department of Public Health said in a news release. 

State officials, along with the members of the Centers for Disease Control and Prevention, will conduct tests to determine if the lake was the source of the woman’s infection.

“It’s strongly believed by public health experts that the lake is a likely source, but we are not limiting the investigation to that source and it’s not confirmed,” Lisa Cox, a spokesperson for the Missouri Department of Health and Senior Services, told the Des Moines Register on Friday.

“Additional public water sources in Missouri are being tested as well,” said Cox.

Cox said officials only learned of the infection on Wednesday.

The amoeba, which is commonly found in warm freshwater such as lakes, rivers, and ponds, can cause a brain infection called primary amebic meningoencephalitis (PAM). Symptoms include fever, nausea, vomiting, stiff neck, seizures and hallucinations.

Infection by Naegleria fowleri can happen when water containing the amoeba enters the body through the nose. From the nose, it travels to the brain “where it destroys brain tissue.” It cannot be contracted by swallowing contaminated water.

Health officials said the infection is extremely rare: since 1962, there have only ever been 154 known cases of PAM diagnosed in the United States. Between 2012 and 2021, just 31 infections were reported in the U.S., 28 of which were infected from recreational waters, according to CDC data.

The infection does not spread from person to person and no other suspected cases of PAM are being investigated, Missouri officials said.