12/02/2025
A brain-eating amoeba has killed nearly everyone it’s infected.
Naegleria fowleri is a microscopic, free-living organism that thrives in warm freshwater: lakes, rivers, hot springs – and in rare cases, poorly treated tap water. It’s officially known as a “thermophilic ameba,” but its nickname is far more chilling: the brain-eating amoeba.
When water containing the organism enters the nose, it can travel along the olfactory nerve to the brain, causing an infection known as primary amebic meningoencephalitis, or PAM. This infection destroys brain tissue and causes the brain to swell. The outcome is almost always fatal.
The numbers are sobering. Between 1962 and 2024, only 167 cases have ever been reported in the U.S. – but just four people survived. Symptoms begin with headache, fever, and nausea, and progress rapidly to confusion, coma, and death, often within five days.
And the risk is growing. Naegleria fowleri has now been detected not just in natural freshwater bodies, but in household plumbing and tap water – especially in southern states where rising temperatures have warmed water systems. A few recent cases have been traced to sinus rinses using contaminated tap water.
You can’t get it from drinking the water. But if it goes up your nose – even just a few drops – it can be lethal.
Experts say prevention is key: use distilled or boiled water for sinus rinses, avoid stirring up sediment in warm freshwater, and keep your head above water in hot springs or lakes.
Learn more:
"Naegleria fowleri Infections." CDC, 2025.
