Naegleria Fowleri This is called the “brain-eating amoeba” because it destroys brain tissue. It lives in warm lakes and rivers, and it can travel up your nose when you swim. Symptoms include headaches, fever, nausea, and vomiting. Later, it can cause stiff neck, seizures, and hallucinations. Most infected people die, but the disease is rare. There have been 35 reported cases in the U.S. in the last 10 years.