Naegleria fowleri is a free-living amoeba found in warm freshwater environments, such as hot springs and poorly maintained swimming pools. It can enter the human body through the nose, typically when people go swimming or diving in contaminated water. This organism is known for causing a rare but severe brain infection called primary amoebic meningoencephalitis (PAM). Symptoms usually appear within a few days of exposure and can include headache, fever, nausea, and stiff neck. PAM is often fatal, making awareness and prevention crucial when engaging in water activities.