Naegleria (nay-GLEER-e-uh) infection is a rare and almost always fatal brain infection. Naegleria infection is caused by an amoeba commonly found in warm, freshwater lakes, rivers and hot springs. Exposure to the amoeba usually occurs during swimming or other water sports.
The amoeba — called Naegleria fowleri — travels up the nose to the brain, where it causes severe brain damage. Most people who have naegleria infection die within a week of showing symptoms.
Millions of people are exposed to the amoeba that causes naegleria infection each year, but only a handful of them ever get sick from it. Health officials don't know why some people develop naegleria infection while others don't.