It's a rare infection in water that can enter the body when people swim or dive in warm freshwater places like lakes and rivers. The amoeba enters the nasal passage through the nose and travels up to the brain, where it destroys it. One can't catch this infection from drinking contaminated water but might get it when using neti pots to clear their nasal passage. Then this amoeba can thrive in the space.  Initial symptoms include headache, fever, nausea, or vomiting. Later symptoms include stiff neck, confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations.