Explained in plain English

What is Naegleria fowleri?

Naegleria fowleri is a microscopic, single-celled amoeba that lives in warm freshwater environments, like lakes and rivers. It's often called a 'brain-eating amoeba' because it can cause a severe brain infection when water containing the amoeba enters the body through the nose. This infection, called primary amoebic meningoencephalitis (PAM), is almost always fatal, as tragically seen in Lillian Smart's case.