Swimmer at Lake of Three Fires State Park infected with brain-eating amoeba

A Missouri resident has been infected by a microscopic organism that causes a rare, life-threatening brain infection after swimming in late June at Lake of Three Fires State Park in Southwest Iowa.

The Iowa Department of Health and Human Services has closed the Taylor County lake to swimming as officials test for Naegleria fowleri, a single-cell, parasitic amoeba that can cause primary amebic meningoencephalitis.

The brain infection is rare — only 154 cases 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 Health Department reported. The infection can’t be spread from one person to another and can’t be contracted by swallowing contaminated water.

“It’s the worst parasite in the world that we know of because it causes such devastating pathology,” said Christopher Rice, a research scientist in the Center for Drug Discovery at the University of Georgia, who studies Naegleria fowleri.

The brain infection is difficult to diagnose because it requires a sample of cerebral spinal fluid, Rice said. He believes some deaths attributed to other diseases causing meningitis may actually be caused by this parasite.

“Naegleria fowleri can kill you within three days, so the longer it takes for diagnoses it can be time ticking away,” he said. There are some drugs available to treat the infection, but they haven’t proved very effective in the lab, Rice said.

Lake ‘likely source’

Lisa Cox, spokeswoman for the Missouri Department of Health and Senior Services, said Friday the infected person is in intensive care at a Missouri hospital. Officials have not disclosed the person’s age or gender.

Naegleria fowleri most often infects children or young adults who are swimming and jumping into lakes and ponds, Rice said. Other cases, many in Pakistan, involved middle-age men who use neti pots to rinse out nasal passages.

The U.S. Centers for Disease Control and Prevention informed Missouri officials Wednesday about the exposure, Cox said. Officials believe the person swam at Lake of Three Fires sometime in the last two weeks of June.

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

Harmful algae and bacteria

Lake of Three Fires, about 25 miles east of Clarinda, is an 85-acre lake popular with boaters and anglers, the Iowa Department of Natural Resources reports. The state park was dedicated in 1935 and is named after a group of Native Americans from the Potawatomi tribe, known as the “Fire Nation,” who once inhabited the area.

The lake 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.

Algae and bacteria provide a welcoming environment for Naegleria fowleri, which are common in soil and water, Rice said.

“We do know the algal blooms and other bacterium do allow the parasite to survive, because that’s generally what it feeds on,” he said.

No testing at other lakes

The CDC is providing the Iowa DNR with equipment to test water at the Lake of Three Fires next week, state Health Department spokeswoman Sarah Ekstrand said Friday.

“The CDC will be doing the analysis. The DNR, Iowa HHS and CDC are working closely to coordinate testing and will provide additional updates as test results become available,” Ekstrand said. “At this time, there are not plans to test other lakes.”

It is unlikely Naegleria fowleri would be carried from one water body to another, Rice said, although there is some research about whether it could be spread by other animals, such as birds.

While the brain infection is rare, people who experience the following symptoms after swimming in any warm body of water should contact their doctor immediately, the state advises:

For more information about Naegleria fowleri, visit the CDC website.

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