Inflammation of brain and meninges caused by free-living amebae ordinarily found in water, soil, and decaying vegetation. Organisms that can cause primary amebic meningoencephalitis include Naegleria fowleri, Acanthamoeba culbertsoni, and other species of Acanthamoeba. The amebae are acquired by swimming in freshwater lakes and sniffing water into the nasal cavities.