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Cedar Rapids, Iowa 52401
Tests have confirmed a brain-eating amoeba was present in a southwest Iowa lake where a Missouri resident was sickened last month.
That person, who swam at Lake of Three Fires State Park in the last two weeks of June, died of the parasitic infection July 7.
Several state agencies completed testing of the water at Lake of Three Fires, 25 miles east of Clarinda, and confirmed the presence of Naegleria fowleri, amoeba that can cause a rare and often fatal brain infection called primary amebic meningoencephalitis, the agencies confirmed Wednesday.
The brain infection is rare — only 154 cases occurred in the United States since 1962 — but it’s nearly always fatal.
Naegleria fowleri can be present in warm, freshwater lakes and ponds. Infection occurs when water is forced up a swimmer’s nose and the organism travels to the brain, where it destroys brain tissue. The infection can’t be spread from one person to another and can’t be contracted by swallowing contaminated water.
Now that testing is complete, the Iowa Department of Natural Resources will reopen the beach at Lake of Three Fires, which has been closed since July 8. The beach will be posted with signs warning swimmers of the presence of the parasite in the water and the risk of infection.
The state does not plan to test other recreational waters.
“There is no rapid, standardized test to detect Naegleria fowleri in water, which is why HHS (Iowa Health and Human Services) and DNR recommend that Iowans assume the parasite is present and limit the amount of water that goes up your nose to help reduce your risk of infection,” the agencies said in a news release.
State officials do not plan to retest the Lake of Three Fires to see if Naegleria fowleri still is present at a later date, Iowa DNR spokeswoman Tammie Krausman said.
This decision is based on U.S. Centers for Disease Control and Prevention guidance against routine testing because “there is no established relationship between detection or concentration of Naegleria fowleri and risk of infection,” Krausman said.
The Iowa DNR still is deciding how long to leave up warning signs at the beach and whether any sort of warning should be posted at other state park beaches, she said.
Christopher Rice, a research scientist in the Center for Drug Discovery at the University of Georgia who studies Naegleria fowleri, told The Gazette earlier this month the parasite feeds on algae and bacteria in the water.
The Lake of Three Fires has frequently been closed to swimming in past summers because of harmful algae that create toxic microcystins that can sicken swimmers. Algae are fed by phosphorus that washes from farm fields into streams and lakes.
The Iowa DNR issued swim warnings at Lake of Three Fires for three weekends in 2021, with two for E. coli bacteria and one for E. coli and microcystins. In 2020, the state advised against swimming there three weeks because of microcystins.
While Missouri has provided no details about the person who died of primary amebic meningoencephalitis after swimming at Lake of Three Fires, Rice said most deaths from the disease have been children and young adults.
A 13-year-old Florida boy was hospitalized with an infection from the brain-eating amoeba earlier this month after swimming July 1 at the Port Charlotte Beach, about 100 miles south of Tampa.
Behaviors associated with the infection include diving or jumping into the water or submerging the head under water, the Iowa DNR reported. Swimmers can reduce their risk by keeping their head out of the water and using nose clips or plugging their nose when going underwater.
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