Brain-Eating Amoeba: Assume There's A Risk In Warm Calif. Lakes

CALIFORNIA — The presence of brain-eating amoeba, an extremely rare but deadly organism found in warm freshwaters, was confirmed Wednesday in a southern Iowa lake after a man who swam there died of amebic meningoencephalitis, the brain infection it causes.

It's the first time the microscopic, single-cell, free-living amoeba, officially known as Naegleria fowleri, has been found in Iowa, but not the first time it's been found in states with severe winters.

Minnesota, for example, had two confirmed brain-eating amoeba reports from 1962 to 2021, according to Centers for Disease Control and Prevention data.

Nationwide, 154 known cases of the illness caused by the amoeba have been reported in nearly 60 years, primarily in Southern states. However, California reports the third highest number of cases in the nation, after Texas and Florida:

1. Texas: 40
2. Florida: 36
3. California: 10
4. Arizona and South Carolina (tie): 8

Only four of the 154 known cases of amebic meningoencephalitis have survived, putting the fatality rate at 97 percent, according to the CDC.

The beach at Lake of Three Fires State Park near Bedford was closed while officials awaited test results, but reopened Thursday with signs warning of the presence of the amoeba, the Iowa Department of Public Health and the state's Department of Natural Resources said in a joint news release.

It can take up to two weeks to identify the presence of the amoeba in freshwater lakes, rivers and streams, according to the CDC, which said new detection tests are under development.

"Therefore," the agency said, "recreational water users should assume that there is a low level of risk when entering all warm freshwater, particularly in southern-tier states."

Here are five things to know about brain-eating amoeba:

Should You Worry?

Worry, no; be cautious, yes. The amoeba enters the body through the nose only. To reduce the risk of an infection, swimmers should take precautions to prevent water from getting up their noses, such as wearing nose clips or swimming with their head above water.

"Picture diving into a lake, and you get water up your nose," University of Iowa epidemiologist Mike Pentella said during a recent interview on Iowa Public Radio's "River to River" program. "Well, if that amoeba is in that water, then it may attach and crawl along your olfactory nerve and get into your brain."

Also, Pentella advised beachgoers to avoid stirring up sediment at the bottom of lakes.

What Are The Symptoms?

A study earlier this year found that temperatures in large lakes can soar above normal six times as frequently as about two decades ago, and could become more likely by the end of the century. The researchers analyzed more than two decades of surface temperature data and concluded nearly all severe lake heat waves were due in some part to climate change.

Scientists worry that dangerous waterborne pathogens such as Naegleria fowleri and Vibrio vulnificus, a flesh-eating bacteria, will multiply faster in increasingly warming waters, ABC News reported last year.

Climate change is "intensifying the opportunity, and creating more opportunity, for these harmful things to cross our paths," Melissa Baldwin, director of Florida Clinicians for Climate Action, told ABC News.

Dr. Sandra Gompf, an infectious disease specialist and professor of medicine at the University of South Florida whose 10-year-old son died in 2009 after contracting the Naegleria fowleri illness while inner-tubing on a Florida lake, told ABC that water temperatures that stay hot longer create greater opportunities for the pathogens to grow.

The presence of brain-eating amoeba outside of southern states are a "red flag" that a problem is brewing, said Darien Sutton, a Los Angeles emergency medicine physician and ABC News medical contributor.

Infections typically occur during prolonged heat waves that cause higher water temperatures and lower water levels, according to the CDC.

What Are The Symptoms?

In the initial stage, symptoms can include a severe frontal headache, fever, nausea and vomiting, according to the CDC. As the disease progresses, symptoms can include a stiff neck, seizures, altered mental status and hallucinations.

Those symptoms are a result of swelling of the brain as the immune system attempts to fight off the amoeba, which releases toxic molecules as it travels to the brain along the olfactory nerve, which controls the sense of smell, CDC medical epidemiologist Dr. Julia Haston told Newsweek.

"Once the amoeba reaches the brain, it begins destroying brain tissue," she said.

Can It Be Treated?

The survival rate has increased over the past decade. In separate cases, a 12-year-old girl and 16-year-old boy, infected in 2013 and 2016, respectively, made full recoveries.

The CDC said the girl was diagnosed within about 30 hours of becoming ill was treated with an experimental drug, miltefosine, and managed with other aggressive treatments, including therapeutic hypothermia — that is cooling the body to below normal body temperatures.
The boy, diagnosed within hours of showing symptoms, was treated with the same drug and therapeutic protocol and the girl in 2013 and also made a full neurologic recovery and returned to school, according to the CDC.

Another person infected in the past decade, an 8-year-old boy, likely suffered permanent brain damage, the agency said. He was treated with miltefosine, but his diagnosis came several days after he became ill. He wasn't treated with therapeutic hypothermia.

"Overall, the outlook for people who get this disease is poor, although early diagnosis and new treatments might increase the chances for survival," the agency said.

Other drugs used to fight the infection include amphotericin B, miltefosine azithromycin, fluconazole, rifampin, and dexamethasone, according to the CDC.

What Other Water Sources Are Affected?

The amoeba can also be found in warm water discharge from industrial plants, naturally hot drinking water sources, poorly maintained and minimally or unchlorinated swimming pool water and water heaters.