Free-living ameba (single-celled living organism) infections are rare and can cause a wide range of symptoms in people. Specific amebae known to cause infections in people include: Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp.
In 2011, a death in a school-aged child from the central region of Virginia was reported. The cause of death was confirmed by the U.S. Centers for Disease Control and Prevention as a free-living ameba called Naegleria fowleri. Naegleria can cause a very rare, but severe, infection of the brain. The ameba is commonly found in warm fresh water (for example, lakes, rivers, and hot springs) and soil. Only one species (type) of Naegleria infects people: Naegleria fowleri.
Naegleria fowleri infects people by entering the body through the nose. This typically occurs when people go swimming or diving in warm fresh water places, like lakes and rivers. In very rare instances, Naegleria infections may also occur when contaminated water from other sources enters the nose. Once the ameba enters the brain, it usually causes a fatal infection called primary amebic meningoencephalitis (PAM).
For more information about free-living ameba infections and recreational water safety, please see the following resources: