Naegleria fowleri is often included in the group "free-living amoebae",[2][3] and this species causes a usually fatal condition traditionally called primary amoebic meningoencephalitis (PAM).
causes mostly subacute or chronic granulomatous amoebic encephalitis (GAE), with a clinical picture of headaches, altered mental status, and focal neurologic deficit, which progresses over several weeks to death.
and Balamuthia mandrillaris are opportunistic free-living amoebae capable of causing granulomatous amoebic encephalitis (GAE) in individuals with compromised immune systems.
The trophozoites are the infective forms and are believed to gain entry into the body through the lower respiratory tract, ulcerated or broken skin and invade the central nervous system by hematogenous dissemination .
[citation needed] In Acanthamoeba infections, the diagnosis can be made from microscopic examination of stained smears of biopsy specimens (brain tissue, skin, cornea) or of corneal scrapings, which may detect trophozoites and cysts.