Naegleria fowleri is a one-celled organism that the U.S. Centers for Disease Control explains is “often called the 'brain-eating ameba' because it can infect the brain and destroy brain tissue." This happens when water containing the amoeba goes up the nose to the brain, causing an infection called primary amebic meningoencephalitis (PAM).

The Missouri Department of Health has begun an investigation into the brain-eating ameba after a person showed symptoms after skiing at the Lake of the Ozarks.