A rare but deadly infection might cause some to think twice before diving into a lake or river this summer.
Anyone swimming in warm freshwater, particularly in southern states, risks contracting a brain-eating amoeba, also known as naegleria fowleri. The infection, mostly reported in summer, is an extreme type of meningitis.
The microscopic amoeba enters the body through the nose. (People cannot get the infection by drinking contaminated water.) Then, travels to the brain, causing it to swell.
More than 97% of people who contract a brain-eating amoeba die, the CDC reports.
The organisms live in warm bodies of water around the world, including hot springs. In the U.S., most infections were linked to freshwater in southern states, but infections have been reported in Minnesota and other northern states, according to the CDC. The ameba can also be found in poorly maintained pools, water heaters and soil. There have been some reports of infections linked to sinus irrigation using contaminated water.
Jennifer Cope, infectious disease physician with the CDC, said the odds of contracting the amoeba are low (only 37 cases were reported between 2006 and 2015), but early detection is critical. Between 1962 and 2015, only three out of 138 total reported cases in the U.S. survived. Last year, a Florida teen became the fourth.
In one case, a 12-year-old girl was admitted to the hospital 30 hours after experiencing symptoms. Experts say quick treatment helped her make a full recovery. An 8-year-old who suffered a brain-eating amoeba infection was diagnosed and treated several days after symptoms. While he is also considered a survivor, the infection left him with permanent brain damage.
“We don’t want people to be alarmed, but there are things to take seriously,” Cope said.
Diagnosing the infection is difficult, because initial symptoms are general: headache, fever, nausea or vomiting. When the disease sets in, people might then experience a stiff neck, confusion, loss of balance, seizures and hallucinations, the CDC reports. After the start of symptoms, people die in less than a week.
To prevent infection, people can hold their nose or use a nose clip when diving into fresh water, or simply keep their head above water to avoid contact. Cope also said it's best not to dig into the sediment, because that’s where the amoeba lives.
While these are recommended measures, they aren’t in any way a guarantee that an infection will be avoided. Brain-eating amoeba infections are so rare, there haven’t been enough cases to study.
“We haven’t tested prevention measures,” Cope said.
Those diagnosed with a brain-eating amoeba infection are often given a cocktail of drugs for greater chance of survival. The drug miltefosine, which was approved by the FDA in 2014, has shown it can fight an amoeba and was given to survivors.
"We recommend a number of drugs be given," Cope said. "We only have a few successes to live by. We do think it’s about timing, recognizing and treating."