Overview of free-living amebas

[Monty]

Free-living amebas are protozoa that live independently in soil or water and do not require a human or animal host. They rarely cause disease, in contrast to the parasitic ameba Entamoeba histolytica, which is a common cause of intestinal infection (amebiasis). Pathogenic free-living amebas are of the genera Naegleria, Acanthamoeba, Balamuthia, and Sappinia.

Three major syndromes occur:

• Primary amebic meningoencephalitis
• Granulomatous amebic encephalitis
• Amebic keratitis

Acanthamoeba and Balamuthia can also cause skin lesions or disseminated disease in immunocompromised people; Acanthamoeba can also cause infection of the sinuses or lungs.